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Notes: The P-H-functional triferriophosphonium salts [{CpFe-(CO)2}3PH]2FeCl4 (1) and [{μ-CO(CpFeCO)2}{CpFe-(CO)2}PH]2FeCl4 (4) are easily deprotonated by DBU to the corresponding unstable triferriophosphanes 2, 5, which subsequently are oxidized by sulfur to the triferriophosphane sulfides {CpFe(CO)2}3P=S (3) and {μ-CO(CpFeCO)2}{CpFe-(CO)2}P=S (6), respectively. The photolysis of 3 results only in its decomposition by elimination of [CpFe(CO)2]2, whereas the photolysis of 6 cleaves off one CO ligand to give the new spiro compound (CpFeCO)(μ-η2-PS){μ-CO(CpFeCO)2} (7), where the P=S unit is η2-bonded to the 15-electron CpFeCO fragment, and the phosphorus atom bridges two 17-electron fragments. Compound 7 shows a new coordination mode of the PS unit where sulfur is also bound to one of the metal atoms. Compounds 6 and 7 can be regarded as first examples of a new class of PS complexes of transition metals. All compounds were characterized by IR, 31P{1H}- and 13C{1H}-NMR spectroscopy as well as mass spectrometry; for 6 the X-ray analytical data are given.

Notes: The reaction of N,N′,N′′-trimethyl-1,3,5-triazacyclohexane chromium trichloride ((Me3TAC)CrCl3, 1) with LiN(SiMe3)2 or NaN(SiMe3)2 in petroleum ether yields nearly quantitatively [Cr{N(SiMe3)2}3] (2) with loss of the Me3TAC ligand. Compound 2 could be crystallized from hexamethyldisilane as [Cr{N(SiMe3)2}3] · (Me6Si2)0,5 which allowed the refinement of the X-ray crystal structure in the trigonal space group P-31c (no. 163) (a = 16.012(3) Å, c = 8.4796(12) Å, V = 1882.8(6) Å3, Z = 2) without severe disorder.

Notes: A series of seven chiral, tripodal N,O,S and N,N,O ligands were prepared in which N stands for a secondary amine or imidazole donor, O for a phenol, and S for a thioether or thiol metal-binding group. Key steps are (1) the construction of ortho-hydroxyacetophenones bearing the phenolic binding group and either a thioether, a protected thiol or an imidazole substituent in the α-position, and (2) subsequent reductive amination with a primary amine. The modular synthesis allows a rapid construction of a variety of structurally related ligands. In three cases, the enantiomers of the racemic products could be separated after condensation with (R)-glyceraldehyde acetonide as chiral auxiliary. The relative configurations of the cyclic N,O- and N,N-acetals thus obtained were established by NOE spectroscopy. X-ray structural analysis of two crystalline N,O- and N,N-acetals allowed the assignment of absolute configurations. Hydrolysis of the dia-stereomerically pure acetals afforded the enantiomerically pure ligands in high yield. By comparison of their CD spectra, absolute configuration could also be assigned to the third pair of enantiomerically pure ligands.

Notes: Asymmetric hydrogenations of prochiral olefines by means of chiral rhodium(I) complexes of the type [Rh(L)(PP*)]A (L = COD, [(Z,Z)-cycloocta-1,5-diene], or NBD (norborna-2;5-diene), PP* = chiral bisphosphane forming seven-membered chelate rings, A = anion like BF4-) are often associated with induction periods caused by partial blocking of the catalyst. NBD complexes are hydrogenated faster than the corresponding COD complexes. Catalytic hydrogenation of COD/NBD mixtures and the determination of the ratio of the Michaelis constants showed that the steady-state concentration of the COD complex under hydrogen is higher than that of the NBD complex. However, under argon the NBD complex predominates owing to its higher thermodynamic stability compared with that of the COD complex as determined by 31P-NMR spectoscopy. This complete reversion of the ther-modynamically determined ratios of COD to NBD complex concentration under hydrogenation conditions was proven by means of UV/Vis spectroscopy.

Notes: 1-Bromo-3,5-bis(trifluoromethyl)benzene (1) can be selectively prepared by treatment of 1,3-bis(fluoromethyl)benzene with N,N'-dibromo-5,5-dimethylhydantoin in strongly acidic media. A number of synthetically useful reactions via 3,5-bis(trifluoromethyl)phenylmagnesium, -lithium, and -copper intermediates were accomplished.

Notes: Lithiated Phosphane Imines. Synthesis and Crystal Structures of [LiCH2PMe2NSiMe3]4 and [LiCMe2P(iPr)2NSiMe3]2The title compounds were prepared by the reaction of Me3-SiNPMe3 and Me3SiNP(iPr)3, respectively, with n-Butylli-thium at 20°C in n-hexane solution. They form white, moisture- and oxygen-sensitive crystals, which were characterized by IR spectroscopy and by crystal structure determinations. - [LiCH2PMe2NSiMe3]4 (1) forms a Li4 tetrahedron, the faces of which are capped with CH2 groups with average Li-C distances of 233 and 251 pm, while the nitrogen atoms occupy the corners of the Li4 tetrahedron. - [LiCMe2P(iPr)2N-SiMe3]2 (2) forms molecules of symmetry C2 in which the lithium atoms have coordination number three by two carbon atoms and one nitrogen atom with Li-C distances of 215.2 and 237.9 pm and Li-N of 192.8 pm.

Notes: The synthesis of 3a starting from compound 1 is described. Copper-catalyzed oxidative coupling of 3b under Hay conditions gives the novel polymer 9 with octatetrayne-cyclobutadiene units.

Notes: (E)-8,8′-(Ethene-1,2-diyl)bis(5-tert-butyl[2.2]metacyclo-phane) (2) was obtained from a McMurry reaction of 5-tert-butyl-8-formyl[2.2]metacyclophane (1). Irradiation of 2 with a high-pressure mercury lamp gave the corresponding (Z) isomer 3. X-ray crystallographic analyses of 2 and 3 show a certain degree of twisting of the bond connecting the meta-cyclophane unit and the central π system due to steric crowding. UV spectra of 2 and 3 and of the charge-transfer complexes [2/TCNE] and [3/TCNE] allow for a discussion of π-π interaction between the central stilbene subunit and the outer benzene rings of the metacyclophane units. Bis[2.2]meta-cyclophanes 2 and 3 reacted regioselectively with hexacar-bonylchromium on the outer benzene rings giving 1:1 and 1:2 complexes 9-14 with tricarbonylchromium. No 1:3 and 1:4 complexes formed due to steric restrictions. Analysis of UV spectral data of the complexed [2.2]metacyclophanes was performed for an indication of π-π interactions in the complexes.

Notes: Here we report on investigations that have revealed for the first time that the Cs+ ion templates the same metal germanium sulfide open-framework as (CH3)4N+ (TMA+), and that metal complexing agents enhance crystal size by at least two orders of magnitude. The synthesis, structures and thermal properties of Cs2FeGe4S10 ·× H2O and TMA2FeGe4S10 are also described. Both have 3D zinc blende-type open-framework structures. These materials have the same connectivity as TMA2MnGe4S10. The tetrahedral sites in the lattice are alternately substituted by pseudo-tetrahedral Fe2+ and adamantanoid Ge4S104- building blocks, covalently linked together by Fe(μ-S)Ge bridge bonds, to give a tetragonal unit cell. The charge-balance of the anionic framework [Fe-Ge4S10]2- is maintained by either Cs+ or TMA+ ions in the cavity spaces. Synthesis of these materials demonstrates an interesting example of a self-assembly process in which a 3D framework is built from molecular precursors. Water adsorption-desorption cycling from room temperature to 200 °C reveals framework flexibility between larger and smaller tetragonal unit cell 14 isotypes. The compound TMA2FeGe4S10 is stable in nitrogen at 350 °C and under vacuum at 450 °C. The corresponding temperatures for Cs2FeGe4S10 are 530 °C and 630°C; it is stable on cooling to room temperature under vacuum, and after subsequent exposure to air. Six hundred thirty degrees celsius is the highest recorded temperature at which the integrity of a non-oxide framework has been maintained. The framework stability and flexibility of “all-inorganic” Cs2FeGe4S10 provides an encouraging example for researchers interested in developing sulfide-based framework materials with practical applications.

Notes: AgClO4 reacts with bidentate ligands 2-(methylthio)pyridine (SMepy) or complexes PPN[Au(Spy)2] [PPN = N(PPh3)2, HSpy = pyridine-2(1H)-thione) or PPN[Au(Sbz)2] (HSbz = benzoxazole-2(3H)-thione), themselves acting as ligands, to give dinuclear complexes [Ag2(μ-SMepy)2](ClO4)2 (1), [AgAu(μ-Spy)2] (2), or [AgAu(μ-Sbz)2] (3), respectively. By treating 1 with [AuCl(tht)] (tht = tetrahydrothiophene), [Au(SMepy)(tht)]ClO4 (4) is obtained which, in turn, reacts with SMepy to give [Au(SMepy)2]ClO4 (5). Similarly, [PdCl2(NCPh)2] reacts with SMepy in 1:1 molar ratio to give [Pd2Cl2(μ-Cl)2(SMepy)2] (6) which reacts with SMepy in 1:2 molar ratio to give [PdCl2(SMepy)2] (7). On the other hand, HSpy reacts with Ag2CO3 to give [Ag2(μ-Spy)2] (8), and (SMepyH)ClO4 reacts with [Au(acac)PPh3] (acacH = acetyl-acetone) to give [Au(SMepy)PPh3]ClO4 (9).

Notes: One tripeptide, five tetrapeptides, and one pentapeptide, all containing His-Xn-His sequences and being blocked at the N and C termini with acyl and amide functions, respectively, were synthesized by solid-phase methods. With one exception their reaction with various zinc salts led to the precipitation of 1:1 (zinc/peptide) complexes. Analytically pure compounds were obtained from zinc tetrafluoroborate and His-Gly-His (1), from zinc chloride (resp. bromide) and His-Gly -Gly-His (2), His-Ala-Gly-His (3), His-Leu-Gly-His (4), His-Pro-Gly-His (5), and His-Pro-Asn-His (6) as well as from zinc sulfate and His-Leu-Gly-His (4) and His-Ala-Pro-Gly-His (7). 1H-NMR data, when available, indicate the coordination of both histidine units to zinc in all cases. The low solubility of the complexes points to their polymeric nature. The only 1:2 (zinc/peptide) complex in this series was obtained from zinc perchlorate and His-Gly-Gly-His (2). An EXAFS study revealed that it contains zinc symmetrically coordinated by four histidine imidazole ligands. Based on the available information it is proposed that all complexes are one-dimensional polymers containg [-Zn-His-Xn-His-Zn-]x backbones.

Notes: The silanediols RN(SiMe3)Si(OSiMe3)(OH)2 (R = 2,4,6-Me3C6H2 4, 2,6-Me2C6H3 5, and 2,6-iPr2C6H3 6) were prepared by the reactions of the respective silanetriols RN(SiMe3)-Si(OH)3 1 - 3 with SiMe3Cl in THF/hexane. Silanetriol 1 in CH2Cl2/hexane solution converts over a period of 4 weeks into the silanediol (2,4,6-Me3C6H2)N(SiMe3)Si(OSiMe2 R)-(OH)2 [R = CH2(2-NH2-3,5-Me2C6H2)] (7). Compounds 4 - 7 were characterized by means of mass, IR and NMR (1H and 29Si) spectroscopy. Additionally, the molecular structures of 4 and 7 were determined by single-crystal X-ray diffraction studies. Compound 4 forms O — H…O hydrogen-bonded tetramers in the solid state. A nine-membered ring formed by an intermolecular O—H…N hydrogen bond is found in the solid-state structure of 7.

Notes: The reaction of [IrCl(C8H14)2]2 (2) with SbiPr3 in the presence of H2 yields the dihydridoiridium(III) complex cis,mer-[IrH2Cl(SbiPr3)3] (3) which on treatment with CO and with HC≡CR (R = Ph, CO2Me) affords the octahedral derivatives [IrH2Cl(CO)(SbiPr3)2] (4) and [IrHCl(C≡CR)(SbiPr3)3] (5, 6), respectively. The stibane ligand trans to hydride in 5 and 6 is rather labile and, therefore, 5 and 6 react with pyridine to give [IrHCl(C≡CR)(py)(SbiPr3)2] (7, 8). Five-coordinate bis-(stibane)iridium(I) complexes [IrCl(C2H4)2(SbR3)2] (10-12) were prepared from [IrCl(C2H4)2]2 (9) and four equiv. of SbR3 (R = iPr, Me, Ph). The X-ray crystal structural analysis of 10 reveals a distorted trigonal-bipyramidal geometry around the metal center with one stibane ligand and the two olefinic ligands in the equatorial plane. Compound 10 reacts with NaC5H5 to yield [C5H5Ir(C2H4)(SbiPr3)] (13) and with different alkynes by partial or complete displacement of the ethene ligands to give trans-[IrCl(PhC≡CPh)(SbiPr3)2] (14), [IrHCl(C≡CTol)(C2H4)(SbiPr3)2] (15), and trans-[IrCl-{=C=C(SiMe3)R}(SbiPr3)2] (16, 17), respectively.

Notes: The preparation, NMR and X-ray diffraction studies of a series of azolylboron hydrides derived from pyrrole, indole, and carbazole coordinated with tetrahydrofuran, pyridine, and imidazole are reported. The azolyl substituents are very electroattractive leading to an acidic boron atom which strongly coordinates with the Lewis bases. The stabilization of the =BH2=groups against disproportionation could be explained in terms of the interactions found between the acidic hydrogen atoms of the heterocycles (C=Hδ+ acceptor) and the hydrides (B=Hδ- donors).

Notes: Molecules containing dimetallated hydrocarbyl groupings are of great chemical interest[1-3]. These groupings often represent intermediates in important catalytic processes[4]. Recently, we have shown that substituted dimetallated olefins can be formed by alkyne insertion into the metal-metal bonds of certain dinuclear complexes[2,5]. Complexes having dimetallated hydrocarbyl groups combined with heteroatoms are quite rare[6]. Herein is described the formation of a dimetallathioimidate grouping by the insertion of an organic isothiocyanates into an unsupported metal-metal bond. Organic isothiocyanates are useful reagents in organic synthesis[7], but the organometallic chemistry of these molecules is not yet well developed[8].

Notes: It is shown that supermolecules with a tetrahedral symmetry and appropriate side-chains exhibit liquid-crystalline phase behaviour. The use of an optimised hydrosylation reaction allows for the synthesis of materials that have four mesogenic groups attached to a siloxane core, where the conformation and the configuration are unambiguous. The materials show low glass transition temperatures and, depending on the spacer length, complex liquid-crystalline morphologies.

Notes: In search of water soluble transition metal complexes with sulfur dominated coordination spheres that model key reactions of nitrogenases, the benzenedithiol derivatives ‘CO2HS2’-H2 (1) and ‘CO2Me-S2’-H2 (2) were synthesized as precursors for multidentate sulfur ligands. The template alkylation of 2 by C2H4Br2 at [Fe(CO)2] fragments yielded a mixture of two diastereomeric C2 symmetrical [Fe(CO)2(‘CO2Me-S4’)] complexes (4a and 4b), which were separated by crystallization. The hydrolysis of the mixture of the diastereomers 4a and 4b led to the isomerically pure tetradentate thioether thiol ligand ‘CO2Me-S4’-H2 (5) proving the regioselectivity of the template alkylation of the asymmetrical dithiol 2. The C1 symmetrical [Fe(‘CO2Me-S2’)2]2- anion is an intermediate of the template alkylation and was isolated as (AsPh4)2 [Fe(‘CO2Me-S2’2] (11), 4a, 5 and 11 were characterized by X-ray structural analysis. Saponification of the methyl ester groups of 5 yielded ‘CO2H-S4’-H2 (7). Treatment of 7 with FeCl2 · 4 H2O in the presence of CO and LiOMe gave a mixture of two C2 symmetrical and water soluble diastereomers of Li2[Fe(CO)2(‘CO2-S4’)] (8). Upon treatment with [RuCl2 (PPh3)3] 7 yielded isomerically pure [Ru(PPh3)2-(‘CO2H-S4’)] (9). 9 also exhibits C2 symmetry and could be reversibly deprotonated to form the water soluble complex K2[Ru(PPh3)2 (‘CO2-S4’)] (10). Treatment of (NBu4)2 (‘CO2MeS2’) with “Ru(NO)Cl3” led to isomerically pure (NBu4)[Ru(NO)(‘CO2Me-S2’)2] (12).

Notes: The syntheses of oxotitanium(IV) meso-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrinate O=Ti(TPPF20) (1), oxotitanium(IV) meso-tetrakis(2,6-difluorophenyl)porphyrinate O=Ti-(TPPF8) (3), and oxotitanium(IV) meso-tetrakis(2,6-dichlorophenyl)porphyrinate O=Ti(TPPCl8) (5) from titanium tetrachloride and the corresponding porphine are described. The structure of 1 was determined by single-crystal X-ray diffraction. The reaction of oxotitanium porphyrinates with aqueous hydrogen peroxide leads to the corresponding light-sensitive peroxotitanium(IV) complexes: Ti(O2)(TPPF20) (2), Ti(O2)-(TPPF8) (4), Ti(O2)(TPPCl8) (6). All complexes are efficient and stable photosensitizers for the generation of singlet oxygen.

Notes: Addition of 3 equivalents of KH · BEt3 to [Me3NH][Me-SiB10H12] followed by addition of one equivalent of SnCl2 or SbI3 affords the stanna-sila-closo-borate(1-) 3 and stiba-sila-closo-borane 4, respectively. [MePh3P] · 3 crystallizes in the orthorhombic space group P212121.

Notes: Intramolecularly Stabilized Metal Amides: 2-(Dimethylaminomethyl)pyrrolyl Complexes of Titanium(III), Vanadium(III), Chromium(III), Cobalt(II) and Nickel(II)By the metallation of 2-(dimethylaminomethyl)pyrrol (HL) with butyllithium the lithium pyrrolide LiL (1) was obtained. The reactions of 1 with TiBr3 · 3 THF, VBr3 · 3 THF, CrBr3 · 3 THF, CoBr2 · 2 THF, and NiBr2 · 1.67 THF result in the formation of the 2-(dimethylaminomethyl)pyrrolyl complexes of type ML3 (2-4), and ML2 (5, 6), respectively. The structures of these new compounds are discussed on the basis of magnetic and visible absorption measurements. An X-ray crystal structure determination of 4 reveals a strongly distorted octahedral environment of the chromium atom with facial arrangement of the ligands.

Notes: The cyclopentadienyl complexes [C5H5Rh(RC≡CR′)(SbiPr3)] (5-8), which were prepared from trans-[RhCl-(RC≡CR′)(SbiPr3)2] (1-4) and NaC5H5 and which contain a labile Rh-SbiPr3 bond, reacted with CO and CNR″ (R″ = Me, tBu) to give the carbonyl and isocyanide derivatives [C5H5Rh(RC≡CR′)(CO)] (9-11) and [C5H5Rh(RC≡CR′)-(CNR″)] (12-16), respectively. On treatment of 12 (R = R′ = Ph; R″ = Me) with SbiPr3, the metallacyclobutene complex [C5H5Rh{κ2(C,C}-C( = NMe)CPh=CPh}(SbiPr3)] (17) was formed; it reacts with excess CNMe or CNtBu to yield the metallacyclopentenes [C5H5Rh{κ2(C,C)-C(=NMe)CPh=CPhC-(=NR)}(CNR)] (18, 19). Similar compounds 20-23 containing a five-membered RhC4 metallacycle were prepared either from [C5H5Rh(RC≡CR′)(SbiPr3)] (7, 8) or [C5H5Rh-(PhC≡CPh)(CNtBu)] (14) and excess isocyanide. The crystal and molecular structures of 17 and 18 (R = Me) have been determined.

Notes: Treatment of 5,10,15,20-tetra-4-pyridylporphyrin [(TPyP)H2] with europium(III) or gadolinium(III) acetylacetonate [Ln(acac)3 · nH2O] (Ln = Eu, Gd) in 1,2,4-trichlorobenzene produced Ln(acac)(TPyP), which reacted with dilithium phthalocyaninate [Li2(Pc)] to give Li[Ln(Pc)(TPyP)] in moderate yields. Upon exposure to air, solutions of these compounds converted slowly to the corresponding neutral complexes Ln(Pc)(TPyP). The new compounds were spectroscopically characterized.

Notes: (Alkynoyl)iron complexes 1, Cp(CO)2Fe(O=CC≡CR) (R = CH3, Ph, SiMe3), were synthesized by applying a mixed anhydride procedure and transformed into the cationic methoxycarbene complexes 2, [Cp(CO)2 Fe(C(OMe)C≡CR)+]-[PF6-]. Primary amines H2NR′ react with the methoxycarbene complexes to furnish exclusively cationic aminocarbene complexes 3, [Cp(CO)2 Fe(C(NHR′)C≡CR)+][PF6-], or (2-methoxyvinyl)aminocarbene complexes 5. The spectroscopic properties of the new complexes are discussed. The (alkynyl)-aminocarbene complexes 3e and 3f were characterized by X-ray crystal structure analysis.

Notes: Metal phthalocyanines (M = Cu, Ni, Co) 3-5 bearing four 16-membered diazadithia macrocycles at the peripheral positions were prepared. Detosylation with concentrated sulfuric acid afforded products containing both sulfonated groups on the aromatic rings of the macrocyclic substituents which are excellently soluble in water and donor sites for binding four CuII ions to give a pentanuclear complex.

Notes: Ab initio MO calculations at the QCISD(T)/6-311++G(3df,2p) + ZPE level show that the thionitrosyl chloride ion, ClNS+•, is 36 kJ/mol more stable than the thiazyl chloride ion, NSCl+•, whereas neutral NSCl is 77 kJ/mol more stable than ClNS [IEa (ClNS) = 9.2 ± 0.3 eV, IEa (NSCl) = 10.5 ± 0.3 eV]. Mild flash-vacuum pyrolysis of the thiazyl chloride trimer (NSCl)3 followed by electron impact ionization resulted in the formation of [N,S,Cl]+• ions (m/z 81). The fragments observed in the CA spectrum of these ions indicate the formation of both NSCl+• and ClNS+• ions. A very weak recovery signal is observed in a neutralizationreionization experiment. This signal is tentatively assigned to the neutral thionitrosyl chloride.

Notes: 4-Butoxynitrobenzene reacts with [Hg(O2CCF3)2] and LiCl to give [Hg(R)Cl] [R = C6H3NO2-3, OnBu-6 (1)] which is symmetrized by Me4NCl to give [HgR2] (2), the crystal structure of which has been determined. The reaction of 2 with Me4N[AuCl4] affords Me4N[Au(R)Cl3] (3) by a facile transmetallation process. Complex 3 reacts with PPh3 (1:1) to give cis-[Au(R)(PPh3)Cl2] (4). The diaryl complex [-Ph-2)(R)Cl] (5) is obtained by reaction of 3 with [Hg-(C6H4N=NPh-2)2] through a second transmetallation reaction. Complex 5 and PPh3 (1:1) give [AuClPPh3] and the C-C coupling biphenyl RC6H4N=NPh-2 (6).

Notes: The synthesis and coordination chemistry of sulfenic, thiosulfinic, and thiosulfonic acid anions are reviewed. Different approaches, which yield the platinum(II) and ruthenium(II) complexes containing the anionic sulfur(0), sulfur(II), and sulfur(IV) oxid ligands, are described. The oxidative addition of thiosulfinates or N-sulfinyl phthalimides to platinum(0) complexes L2Pt(C2H4) [L = PPh3, 1/2 PPh2CH2CH2PPh2, 1/2 (R,R)-(-)-DIOP, 1/2 (C5H4PPh2)Fe(C5H4PPh2) leads to sulfenato complexes; those of N-thiosulfinyl phthalimidies or trisulfid 1-oxides afford the thiosulfinato complexes. Moreover, the reactions of CpRu(PPh3)(L)(SH) (L = CO, PPh3) with N-sulfinyl phthalimides forming the thiosulfinato moiety, are reported. The spectroscopic, structural and chemical properties of these complexes are discussed.

Notes: The cationic iron (alkynyl)aminocarbene complexes [Cp(CO)2Fe(C(NHR)C≡CSiMe3][PF6], (R = C6H5, p-CH3C6H4) 1 derived from aromatic amines smoothly react with cyclopentadiene in dichloromethane to yield the cycloadducts 2. No reaction was observed for complexes derived from sterically demanding aliphatic amines, like L-alanine tert-butyl ester. For comparison, the alkynyl-substituted acyl iron compounds Cp(CO)2Fe(C=O)C≡C̊ (R = SiMe3, C6H5) 3 were investigated, requiring TiCl4 catalysis to undergo the cycloaddition reaction. The structures of the cycloadducts 4 were determined by X-ray crystallography.

Notes: Treatment of (cdt)Ni (cdt: cyclododeca-1,5,9-triene) with 2 equivalents of 2-methyl-4-trimethylsilyl-3-butyn-2-ol leads to the selective formation of the homoleptic complex (alkyne)4Ni3 (compound 3), which can be isolated in excellent yields. The solid-state structure of 3 exhibits three Ni centers, forming a bent Ni3 chain connected by two bridging alkynes. The other two alkynes are terminally coordinated. Additionally, the trimeric units are stabilized by three intramolecular hydrogen bonds. Two intermolecular hydrogen bonds connect the trimeric units to form a polymer rope. According to the 13C- and 1H-NMR spectra in THF the structure of the complex 3 in solution is very similar to that in the solid state. The reaction of 3 with some alkynediols and with 2,5,5-trimethylhex-3-yn-2-ol affords compounds of the type (alkyne)2Ni. Cot (cot: 1,3,5,7-cyclooctatetraene) converts 3 into [(cot)Ni]2, which in turn reacts with 2,5-dimethylhex-3-yne-2,5-diol to form the dimeric complex (alkyne)2Ni2(cot) 6. X-ray analysis of 6 reveals a very symmetrical structure in which cot connects both Ni(0) centers at opposite sides of the ring system.

Notes: The SO2 coordination mode at the rhodium complex [ClRh(P∼O)()] (1) [ = η2(O,P)-chelated Cy2PCH2CH2OCH3 ligand; P∼O = =1(P)-coordinated] is controlled by the hemilabile ligand Cy2PCH2CH2OCH3 and shows a dependence on the polarity of the solvent. In polar organic solvents (e.g. acetone) the addition of sulfur dioxide results in the formation of a trigonal-pyramidal oriented SO2 group in [ClRh(η1-SO2)(P∼O)()] (2a). However, in nonpolar media (e.g. n-hexane) a trigonal-coplanar geometry of the SO2 unit in [ClRh(η1-SO2)(P∼O)2] (2b) is favored.

Notes: Pentacarbonyl(allenylidene)chromium and -tungsten, [(CO)5—M=C=C=CR2] (M=Cr, R=C6H4CH3-p(1a), C6H4OCH3 (1b); M=W, R=C6H4CH3-p (1c), react with the alkynyl complexes [Cp(CO)2Fe—C≡CR′] (R′ = nBu (2), Ph (4)), [Cp*(CO)2Fe—C≡CnBu] (6), [Cp(CO){P(OMe)3}-Fe—C≡CnBu] (8) and [Cp(PPh3)Ni—C≡CnBu] (10) by cycloaddition of the C≡C bond of the alkynyl complexes to the Cα=Cβ bond of the allenylidene ligand to give 3a-c), (5), (7), and respectively. The cycloaddition is highly selective. The spectroscopic data of these 1,3-heterobinuclear complexes indicate a delocalized π-system (M=Cr, W; Y=[Fe(CO)2Cp], [Fe(CO)(P{OMe}3)Cp], [Fe(CO)2Cp*], [Ni(PPh3)-Cp]). X-ray structural analyses of the compounds 3a, 9a, and 11c reveal a “butterfly” conformation of the four-membered ring. Its puckering angle is 142° (3a), 152° (9a), and 151° (11c). All Complexes exhibit a moderate to strong negative solvatochromic behavior. The extent of the solvatochromic effect depends on [(CO)5M] and Y and considerably decreases when C=CR2 is replaced by e.g. CMe2.

Notes: Optically active alcohols (ee ≥ 98%) such as 1-phenylpropanol, 1-(2-naphthyl)ethanol, 1-tetralol, and 1-indanol were transformed into diethyl phosphates 7a-d. sBuLi/TMEDA  -  induced phosphate - phosphonate rearrangement in diethyl ether furnished tertiary α-hydroxyphosphonates 8a-d of high enantiomeric purity (ee 94-98%) in yields of 43-83% with retention of configuration. The enantiomeric excesses were determined by using homochiral t-butyl(phenyl)phosphinothioic acid as chiral solvating agent.

Notes: The cationic tetracarbonyl complex cis-[Mn(CO)4-(S2CPCy3)]+ undergoes addition of hydride ion to the central carbon of the S2CPR3 ligand to afford, after spontaneous dimerization with loss of CO, the dimer [Mn2(CO)6{μ-S2C(H)PCy3}2] (5a), which was characterized by analytical and spectroscopic methods as well as by X-ray diffraction. In the molecule of 5a each S2C(H)PCy3- ligand is coordinated to one manganese in an η2-S,S′ chelate fashion, and one sulfur of each ligand serves as a bridge to bind the other manganese atom, thus forming a distorted Mn2S2 square. This appears to be a very stable arrangement. Compound 5a can be more easily prepared by treating the perchlorato complex [Mn(CO)3(S2CPCy3)(OClO3)] (2a) with NaBH4. This procedure is general and can be used for the preparation of several derivatives containing either manganese or rhenium [M2(CO)6{μ-S2C(H)PR3}2] 5a-d. The reaction of cationic tricarbonyl complexes [M(CO)3(S2CPR3)(PPh3)]PF6 (M = Mn, Re) with NaBH4 produced the same dimers 5a or 5c by displacement of the PPh3 ligand. Treatment of the dimer 5a with excess PEt3 or P(OMe)3 leads to the cleavage of the bridges and loss of one CO and the PR3 group from the S2C(H)PR3 unit to afford ultimately the dithioformate complexes [Mn(CO)2(S2CH)(L)2] [L = PEt3, P(OMe)3].

Notes: Organo-Zinc Phosphaneiminato Complexes with Heterocubane StructureThe organo-zinc heterocubanes [ZnR(NPMe3)]4 with R = CH3 (1) and n-C4H9 (2) were prepared by the reaction of [ZnBr(NPMe3)]4 with MeLi and nBuLi, respectively, in hexane solution. In a similar reaction of nBuLi with [ZnI(NPMe3]4 the phosphaneiminato complex [Zn4I(nBu)4(NPMe3)3] (3) is formed. 1-3 were characterized by IR, NMR and MS spectroscopy, and by crystal-structure determinations. 1 and 2 possess heterocubane structures in which the zinc atoms are linked via μ3-N bridges of the phosphaneiminato groups, and all bond angles in the Zn4N4 core are close to 90°. A distorted heterocubane structure is observed for 3 with one of the NPMe3 moieties replaced by an iodine atom.

Notes: Sulfoxonium ylides 3a-h were synthesized by silylation of the cyclic methylene disulfones 1,3-dithietane 1,1,3,3-tetraoxide (1) and 1,3,5-trithiane 1,1,3,3,5,5-hexaoxide (4) with the silylating agents silyl nonafluorobutanesulfonates. The structure and constitution of the ylides were established with 1H-NMR, 13C-NMR, 29Si-NMR spectroscopy, mass spectrometry, and elemental analysis. On the route to the sulfoxonium ylides a new class of unsaturated disulfenes 7, 8, 12, 13 of 1 and 4 were synthesized via Knoevenagel and substitution reactions. Dianions of newly formed alkyl disulfenes 16a, b, e, f, and the trianion 17 were prepared and characterized by 1H-NMR and 13C-NMR spectroscopy and compared with the results of the ylides.

Notes: Addition of CS2 and Other Heteroallenes to the 16-Electron Osmium(0) Complexes trans-[OsCl(NO)(PiPr2R)2]The coordinatively unsaturated 16-electron compounds trans-[OsCl(NO)(PiPr2R)2] (1: R = iPr; 2: R = Ph) react with CS2 and COS to form the 1:1 adducts [OsCl(NO){κ2(C,S)-S=C=S}(PiPr2R)2)] (3, 4) and [OsCl(NO){κ2(C,S)-S=C=O}-(PiPr2R)2] (6, 7), respectively. While compounds 3, 4 are inert toward PMe3, the Os(COS) complexes 6, 7 react with tri-methylphosphane by abstraction of sulfur to give (OsCl(NO)-(CO)(PiPr2R)2] (8, 9). From 1 or 2 and phenylisothiocyanate the corresponding 1:1 adducts (OsCl(NO){κ2(C,S)-S=C=NPh}(PiPr2R)2] (10, 11) are obtained. Protonation and methylation reactions of 10 (R = iPr) with HBF4 or CF3SO3Me lead, by addition of the electrophile to the C=N nitrogen atom, to the formation of [OsCl(NO){κ2(C,S)-S=CNHPh}-(PiPr3)2]BF4 (12) and [OsCl(NO){κ2(C,S)-S=CN(Me)Ph}-(PiPr3)2]CF3SO3 (13). Treatment of 1 with diphenylketene yields [OsCl(NO){κ2(C,O)-O=C=CPh2}(PiPr3)2] (14). The X-ray structure analyses of 10 and 14 confirm the coordination of phenylisothiocyanate via S and C and of diphenylketene via O and C, respectively.

Notes: 8-Lithioquinoline reacts with 2,3,4,5-tetramethylcyclopentenone to give 8-quinolylcyclopentadiene (1/2) after acidic workup and treatment with ammonia. Two of the possible three isomers are formed; the acidic protons on the Cp rings show unusual downfield shifts in the 1H-NMR spectra. Treatment with strong bases led to the intensely coloured anionic 4 which was converted into the trimethylsilyl derivative 5. This is a suitable starting compound for the trihalotitanium and -zirconium compounds 6 and 7. The two complexes were investigated by crystal structure analyses. In both cases the quinolyl nitrogen atom is coordinated to the metal.

Notes: On the Silaethene tBu2Si=C(SiMe3)2, and the Structure and Reactivity of Its [4 + 2] Cycloadduct with Ph2C=OFrom tBu2SiF—CLi(SiMe3)2 by LiF elimination only Me2Si= C(SiMe3)(SiMetBu2) (1b) instead of tBu2Si=C(SiMe3)2 (1a) is isolated. With benzophenone, silaethene 1b (from its THF adduct 1b · THF) forms at -78 °C a yellow [4 + 2] cycloadduct (5) and a colorless [2 + 2] cycloadduct (6). With increasing temperature 5 transforms into 6, and 6 transforms -more slowly - into the yellow [4 + 2] cycloadduct (7) of 1a and Ph2CO. It follows from this that the migration equilibrium 1a ⇄ 1b really exists. The structure of 7 shows a planar —O—CPh=C6H5-framework with the cycloadded atoms Si and C from -tBu2Si—C(SiMe3)2- located above the plane. The =C6H5—C bond (1.62 Å) is exceptionally long. 7 is a source for 1a which is trapped by acetone (formation of an ene product) and by benzaldehyde [formation of a [2 + 2] cycloadduct, unstable against cycloreversion into PhHC=C(SiMe3)2 and tBu2SiO-containing substances]. Reaction of 7 with trimethylsilyl azide, less reactive than acetone or benzaldehyde, leads - by way of 1a which transforms into 1b - to a trapping product of 1b (formation of a [3 + 2] cycloadduct, unstable against transformation into (RMe2Si)(Me3Si)CN2 with R = (Me3Si)2N, or cycloreversion into (tBu2MeSi)(Me3Si)CN2 and Me2SiNSiMe3-containing substances). Reaction of 1b or 1b · THF with acetone leads only to an ene reaction product of 1b. This means, that only undetectable amounts of 1a or 1a · THF are in equilibrium with 1b or 1b · THF. A minor substance which is shown by NMR at low temperatures besides 1b or 1b · THF is interpreted as a rotamer of 1b or 1b · THF.

Notes: In the presence of Lewis acidic derivatives of group 13 elements, phosphaalkynes 7 undergo spirocyclotrimerization with incorporation of the corresponding Lewis acids to form 10a-f. Scope and limitations of this novel cyclooligomerization process are examined. Starting from the spirocyclotrimer 10a reaction with the Lewis base dimethyl sulfoxide, we have in hand for the first time a method for the selective generation of two isomeric triphospha Dewar benzene derivatives (18, 19). Both can be trapped efficiently by further reaction with the phosphaalkyne to furnish the two novel phosphaalkyne cyclotetramers 20 and 21, both still possessing a phosphorus-carbon double bond. In the case of 21, further functionalization of the phosphaalkene unit is possible by [3 + 2] cycloaddition with a nitrile oxide (→ 23).

Notes: The substituted 6-hydroxy-trans-3-hexenoic acids 2a and 2b are prepared by an organometallic template reaction involving a sequence of CC coupling reactions between a CO2 equivalent, butadiene, and 3-cyclopenten-1-one or 3,4-diphenyl-3-cyclopenten-1-one, respectively. In the crystal 2a assembles to form an infinite ribbon-type structure, exhibiting an alternating array of 12 and 18 atom-containing loops. The former are each constructed by an alternating CO2H/OH/CO2H/OH sequence, originating from four different monomeric units, that are linked together by means of hydrogen bonds. Two complementary ribbons of 2a are connected by van der Waals interactions to form staples that constitute the microscopic building blocks of the true (2a)n structure in the crystal. Stacks of cyclopentene π bonds are oriented inside the columnar structure of 2a. Acid 2b also forms a related ribbon-like assembly in the solid state. Here the bulky 3,4-diphenylcyclopentadienylidene moieties are oriented laterally at the ribbons, and van-der-Waals interactions with adjacent ribbons construct a three-dimensional hydroxyhexenoic acid network.

Notes: Some dithioxophosphoranes 3 stabilized by intramolecular coordination with a dialkylamino group were prepared, and their structures were analyzed by X-ray crystallography involving [2,4-di-tert-butyl-6-(isopropylmethylamino)phenyl]- (3c), {2,4-di-tert-butyl-6-[(dimethylamino)methyl]phenyl}- (3f), and {2,4-di-tert-butyl-6-[2-(dimethylamino)-1,1-dimethylethyl]phenyl}dithioxophosphorane (3h). The bond between the phosphorus atom and the aromatic ring is flexible and the angle narrows with decreasing ring size of the intramolecular coordination. The 31P-NMR signals are shifted to higher field with increasing ring size of the intramolecular coordination or strength of coordination. Similarly, the corresponding diselenoxophosphoranes 4 were prepared. Both their 31P- and 77Se-NMR signals are shifted to higher field with increasing contribution of intramolecular coordination.

Notes: Indium(III) and tin(IV) thiocarboxylates were prepared and characterized on the basis of their IR, 13C- and 19Sn-NMR data. Indium tris(thiobenzoate) (1) decomposes into a sulfido complex In (S)[S(O)CPh] (2a). The corresponding tris(thioacetate) In[S(O)CMe]3 is thermally too unstable to be isolated. The anionic tetrakis complex [Et3NH]{In[S(O)CPh]4} (3) was characterized by X-ray crystallography which revealed a distorted tetrahedral coordination at the In atom. X-ray diffraction analysis of the complexes BuSn[S(O)CPh]3 (4) and Cl2Sn[S(O)CPh]2 (7) showed distorted tetrahedral and cis-octahedral structures, respectively.

Notes: The coordination behaviour of ligands having the same basic constitution RN=NC(=X)R′ (X = O, NR″, S) in their tripod cobalt derivatives has been analyzed. The ligands themselves may be considered as neutral heterodiene compounds and are in this respect vinylogues to diazenes RN=NRy′. Two- electron reduction of these neutral species results in dianionic heterosubstituted heteroolefins RN- -N=C(X-)R′. Due to their redox ambiguity the oxidation state of the metal M in chelate complexes is not a priori evident. Compounds tripod [5: X, R′ = O, Ph; 6; (X, R′) = (py); 7: X, R′ = S, NH2] are best described as containing low-spin Co(III) and dianionic ligands. Co(II) species are obtained with diethyl azodicarboxylate EtOOCN=NCOOEt as the ligand. In the mononuclear compound, with only one nitrogen and one carbonyl oxygen of the ligand acting as donor groups, the neutral ligand is coordinated to give the high-spin cobalt(II) species tripod (8). In the dinuclear compound 9 with both of the nitrogen atoms and carbonyl groups involved in coordination the dianionic ligand bridges two high-spin cobalt(II) centers to give tripod (9) as a derivative with two fused five-membered chelate rings. In addition to the conventional analytical techniques X-ray structure analyses, cyclovoltametric measurements, magnetic susceptibility and ESR data are used to characterize the compounds.

Notes: Transition-Metal Stannyl Complexes, 10 - Molybdocen and Wolframocen Derivatives with Two Different Main-Group-4 LigandsReactions of Li[Cp2MSnPh3] (M = Mo, W) with CH3I, BuBr, PhCH2Br, PhC(O)Cl or Br(CH2)nBr (n = 4,5) yield Cp2M(R)SnPh3 [R = CH3, Bu, CH2Ph, C(O)Ph, (CH2)nBr], while tBuBr or CH3C(O)Cl give the hydrido complexes Cp2M(H)SnPh3. A silyl stannyl complex is only obtained from Li[Cp2WSnPh3] and Me3SiOSO2CF3, but not with Me3SiCl or from the anionic Mo complex. In contrast, the reactions of chlorostannanes provide the bis(stannyl) complexes Cp2M(SnR′3)SnPh3 or Cp2M(SnR′2Cl)SnPh3. R/Cl exchange at the tin atom is observed when an excess of the chlorostannane is used. Upon reaction of Li[Cp2MSnPh3] with Ph3PbCl only Cp2M(PbPh3)SnPh3 is formed, while a mixture of Cp2M(PbMe3)SnPh3 and Cp2M(PbMe2Cl)SnPh3 is obtained with Me3PbCl due to redistribution reactions. The structures of Cp2W(SnPh3)C(O)Ph, Cp2W(SnPh3)SntBu2Cl and Cp2W(SnPh3)PbMe2Cl were determined by X-ray structure analyses.

Notes: Pentacarbonyl(thiobenzaldehyde)tungsten und pentacarbonyl(selenobenzaldehyde)tungsten (1a and 1b) undergo a thermal [2 + 2] cycloaddition with several vinyl ethers to give highly substituted transition metal-coordinated thietanes and selenetanes. The addition is highly regio- and stereospecific. The products undergo acid-catalyzed rearrangements, which lead to thermodynamically more stable diastereomers of the thietanes and selenetanes. The stereochemistry of both addition and rearrangement was established by reaction of deuterium-labeled vinyl ethers and by reaction of the cis and trans isomers of ethyl propenyl ether. The crystal structure of the bicyclic addition product of 1a and 3,4-dihydro-2H-pyran is reported.

Notes: Highly substituted pyrazolylborate ligands TpR,Me were used to limit the coordination number of zinc towards cysteine- and histidine-derived coligands. Monodentate thiolate attachment (→ 1a-f) was achieved with N- and C-protected cysteine, monodentate carboxylate attachment (→ 3) with N-protected histidine. C-protected cysteine was found to form a five-membered N,S-chelate ring (2). While imidazole coordination with N- and C-protected histidine could not be achieved, cationic pyrazolylborate-zinc-coligand complexes [TpZn-L]+ (4a, b) were obtained for L = 2-methylimidazole. The new complexes were characterized by their spectra and three structure determinations.

Notes: Organotungsten-selenolato complexes were prepared in moderate yields by insertion of selenium into the alkali metaltungsten bonds of MSeW(CO)3cp (M = Li, Na) and subsequent reactions with the organohalides o-, m-, and p- C6H4(CH2Br)2, C6H5CHBr2, m-C6H4(CHBr2)2 and C6H5CCl3. The 77Se-NMR data of the new complexes are discussed and compared with those of related complexes derived from organomonohalides. Moreover, the X-ray crystal structures of C6H5CH2W(CO)3cp (1), μ-[m-C6H4{CH2SeW(CO)3cp}2] (3), μ-[p-C6H4{CH2SeW(CO)3cp}2] (4), and C6H5CH[SeW-(CO)3cp]2 (5) were determined. In complex (1), the W-CH2 bond length is 2.374 Å; the W-Se bond lengths in the complexes 3, 4 and 5 are all in the range 2.625-2.655 Å, corresponding to W-Se single bonds.

Notes: The synthesis of a terphenyl derivative complexed by the cationic moiety Cp*Ru+ by Suzuki coupling of [Cp*Ru(BrC6H4Br)]OTf with phenyl boronic acid under catalysis of Pd(PPh3)4 in a DME-water mixture at 85°C in quantitative yield is reported. The stable coupling product 3 was characterized by X-ray crystal structure analysis.

Notes: Ruthenium complexes catalyze a variety of addition or isomerization reactions that are highly atom economical. Terminal alkynes react with allyl alcohols to form β,γ-unsaturated ketones that can be readily isomerized to α,β-unsaturated ketones via transient vinylidene complexes. A cyclization via a transient allenylidene complex concomitant with this addition represents a novel way to build heterocycles. Ancillary studies with these catalysts revealed an internal oxidation reduction whereby allyl alcohols are isomerized to saturated ketones and propargyl alcohols are isomerized to α,β-unsaturated carbonyl compounds. Consideration of the reaction mechanism led to a general Alder ene type reaction wherein alkynes serve as the enophile and alkenes serve as the ene component. These discoveries have led to a number of efficient total syntheses of biologically interesting targets. Mechanistic investigations into the activation of a ruthenium complex led to the discovery of a novel bis-homo-Diels-Alder reaction of 1,4-cyclooctadiene.

Notes: Stimulated by the recent detection of nitrosyl azide (N3—N=O), we investigated the stability of the sulfur analogues thionitriosyl azide (N3—N=S) and thiazyl azide (N3—S≡N) by using ab initio MO calculations up to the QCISD(T)/6-311+G(d)//QCISD/6-311G(d) + ZPE level. Both azides have a similar energy content. While thionitrosyl azide is not stable with respect to N2 elimination, thiazyl azide resists to this process by an energy barrier of about 110 kJ/mol. The NS and N3 fragments resulting from homolytic cleavage lie about 100 kJ/mol above the azides. The five-membered ring is thermodynamically much more stable than both azides but kinetically unstable with respect to cheletropic decomposition yielding N2S + N2. Overall, trans-thiazyl azide is the most likely candidate for experimental observation of, for example, the reaction of NS+ salts with the azide anion. IR wavenumbers of the azides were also predicted.

Notes: Syntheses, Properties, and Crystal Structures of the Titanium(III) Amido Complexes Ti[N(SiMe3)2]3, [TiCl2{N(SiMe3)2}(THF)2], and [Na(12-Crown-4)2][TiCl2{N(SiMe3)2}2]TiCl3(THF)3 reacts with NaN(SiMe3)2 to furnish [TiCl2{N(SiMe3)2}(THF)2] (1), whereas in the presence of 12-crown-4 the ionic amido complex [Na(12-crown-4)2][TiCl2{N(SiMe3)2}2] (5) is obtained besides [Na(12-crown-4)2][TiCl4(THF)] (4). On the other hand, the titanium(III) amido complex Ti[N(SiMe3)2]3 (2), the crystal structure of which was solved, reacts with NaN(SiMe3)2 in the presence of 12-crown-4 with deprotonation of one of the methyl groups to give the carbometalated complex [Na(12-crown-4)2][Ti{N(SiMe3)2}2{N(SiMe 3CH2)}] (3).

Notes: Complexes of Halide Ions with Diiodoacetylene. The Crystal Structures of PPh4[X(I-C≡C-I)2] with X = Cl, Br, IThe complexes PPh4[X(I-C≡C-I)2] with X = Cl (1), Br (2), and I (3) have been prepared from the phosphonium salts PPh4X and 1-C≡C-I in dichloromethane solutions. 1-3 form colourless crystals, which according to crystal structure analysis crystallize isotypically in the space group P421m with two formula units per unit cell. The diiodacetylenes are coordinated by the halide ions X- in a distorted tetragonal fashion, the I-C≡C-I molecules being in μ2-bridging function. Thus, a polymeric anionic network [X(I-C≡C-I)2]nn- with a layered structure results.

Notes: The synthesis and coordination chemistry of 2-(2-pyridyl)-phosphinines and 2,2′-biphosphinines are reviewed. A noteworthy series of homoleptic complexes of 4,4′,5,5′-tetramethyl-2,2′-biphosphinine (tmbp) with Cr(0), Mo(0), Wo(0) and Ni(0) are described. A [Cu(bpy)(tmbp)]+ cationic polymer has been characterized by X-ray analysis. Ruthenium, manganese and rhenium chelates were also obtained. With Mn2(CO)10, a (tmbp)-Mn2(CO)6 complex is formed where tmbp acts as an eight electron donor.

Notes: The reaction of InBr/InBr3 or InBr/BrIn[(CH2)3NMe2]2 with the transition metal dimers [L(CO)nM]2 {L = CO, Cp, C5H4[(CH2)2NMe2]; M = Fe, Co, Ni; n = 1-3} in THF or dioxane gives in almost quantitative yield the transition metal indium complexes L(CO)nM—InBr2(Do) (Do = THF, NC7H13) and L(CO)nM—In[(CH2)3NMe2](Br) respectively. The new compounds were characterized by elemental analysis, infrared v(CO) spectroscopy, NMR, and mass spectrometry. An X-ray single crystal structure determination of (η5-C5H5)(CO)-Ni-InBr2(NC7H13) (1a) revealed a short Ni-In bond of 246.3(1) pm.

Notes: An improved synthesis of [(2-phosphanylethyl)cyclopenta-dienyl]cobalt(I) chelate complexes is presented, in which the paramagnetic chloride 3 is a precursor of the ethene complex 4. The latter readily undergoes ligand exchange reactions which in the case of bidendate reagents (1,5-cyclooctadiene, 1,2-bis(diisopropylphosphanyl)ethane, 2,2′-bipyridine, nor-bornadiene) cause a decomplexation of the phosphane arm at room temperature with formation of 7, 5, 6, 8. The ethene ligand in 4 can be replaced by alkynes under equally mild reaction conditions (formation of 9, 11 - 16). The reaction with ethyne results in the formation of vinylidene complex 10. The yields of the reactions with nonaromatic alkynes could be improved by treating 3 with the alkyne in the presence of sodium amalgam. The unsubstituted vinylidene complex 10 and its tert-butyl derivative 17 were obtained by this route in 38 and 40% yield, respectively.

Notes: Cesium-Fluorine Four-Membered Rings as Structural Motive in Cesium Triorganofluoro Metalates of Group 13The reactions of AlMe3, GaMe3, and InMe3 with CsF in acetonitrile furnish the corresponding trimethylfluoro metalates Cs[Me3MF] (1: M = Al, 2: M = Ga, 3: M = In). The salt-like compounds 1 - 3 were characterized by NMR, IR, and MS techniques as well as by X-ray structure analysis. Cs2F2 four-membered rings are the structure-dominating units in all three compounds. Compound 1 consists of puckered layers of weakly associated Cs2F2 rings parallel to (100), while the four-membered rings in 2 form infinite ladder-type chains. The Cs-F rings in 3 build up a heterocubane with a Cs4F4 core by ring stacking.

Notes: The crystal structures obtained by X-ray methods of (tert- butoxy)alane and -gallane (tBuOMH2) are isotypic and are composed of discrete centrosymmetric dimers. The dimers arise from almost symmetrical Al—O—Al [1.810(3), 1.815(3) Å] and Ga—O—Ga [1.902(9), 1.908(9) Å] bridges forming a central rhombohedral four membered M2O2 cycle [O—Al—O 81.0(2)°, O—Ga—O 78.6(5)°] with the metallic atoms in a distorted tetrahedral environment. When one of the hydride ligands on the metals is further substituted by tert-butoxy, the formation of (tBuO)2AlH and (tBuO)2 GaH is observed. These two compounds crystallize in different lattices and space groups, but they are nevertheless very similar in their structure: the centrosymmetric M2O2 cycle is maintained [Al—O 1.817(3), 1.817(3) Å; Ga—O 1.904(4), 1.907(4) Å] As expected, the terminal Al-O [1.675(3) Å] and Ga—O [1.783(4) Å] distances are considerably shorter than the bridging ones.

Notes: Treatment of hexa-tert-butylcyclotrigermane (3) with CCl4, Br2, and I2 furnishes the correspondingly substituted 1,3-dichloro- (4), 1,3-dibromo- (5), and 1,3-diiodotrigermanes (6). The symmetries of the molecules of 5 and 6 are very similar (point group C1) revealing gauche-anti conformations and different Ge—Ge bond lengths. However, while 5 crystallizes as a racemate, 6 forms a conglomerate of enantiomerically pure crystals. The X-ray structure analysis of the 1,3-dimethyltrigermane (7) derivative, derived from 6 by a sequence of metalation and methylation reactions, reveals more symmetrical molecules of the point group C2 which also crystallize as a racemate. Irradiation of 3 leads to tetra-tert-butyldigermene (8) and di-tert-butylgermylene (9) which could be trapped by addition and cycloaddition reactions with selenium, tellurium, and 3,5-di-tert-butyl-1,2-benzoquinone.

Notes: The cationic ferracyclic carbene complexes 1 react with carbon nucleophiles like lithium enolates and organocuprates to give the corresponding 4-substituted 1, (3E)-diene tricarbonyl-iron complexes 6 and 9. The reaction is thought to proceed by initial attack on the allyl terminus and subsequent ferra Claisen-Ireland rearrangement of the intermediate (η2 alkene)carbene complex 4. This rationale is supported by the isolation and characterisation of analogous aminooxocarbene derivatives 8. With sterically demanding enolates products 6 are formed in diastereomeric ratios of up to 90:10, thus demonstrating the inductive power of the chiral metallacycle in 1. Lithium acetylides as carbon nucleophiles react with 1 according to a novel cascade to give regio- and stereospecifically 2,5,5-trisubstituted-cyclopentenones 10 suggesting a concerted formation of four C=C bonds together with a CO insertion and a formal carbene transfer step.

Notes: The zinc complex chemistry of the tridentate thiol ligand N- (2-mercaptophenyl)(2-picolyl)amine (MPPAH) differs considerably from that of the aliphatic analogue N-(2-mercaptoethyl)(2-picolyl)amine reported previously. This is due to the lower basicity and hence bridging tendency of its aromatic thiolate function. With zinc salts of oxo anions the 1:1 complexes (MPPA)ZnX (1a-c: X = ONO2, OAc, OBz) are formed which according to spectroscopic data are monomeric while the halide (MPPA)ZnBr (2) seems to be polymeric. In the absence of coordinating anions the monomeric 2:1 complex (MPPA)2Zn (3) results which according to a crystal structure determination contains tetrahedral zinc coordinated by one MPPA ligand in a tridentate fashion while the other is only monodentate and sulfur-bound. A similar N2S2 coordination can be deduced for the 1:1:1 complex (MPPA)Zn(STrt) (4) resulting from ZnEt2, MPPAH and triphenylmethanethiol.

Notes: Reaction of bis(diisopropylamino)phosphenium triflate (1[CF3SO3]) with silver salts AgY [Y- = CF3CO2- (2a), CF3-SO3- (2b), CH3CO2- (2c)] affords neutral complexes [{(iPr2N)2(Y)P} Ag(OSO2CF3)] (3a-c). While 3a, c are stable up to ambient temperature, 3b is only stable at low temperature and in equilibrium with the cation 1. The constitution of 3a-c was derived from multinuclear (1H, 13C, 31P, 109Ag) NMR spectra. Compound 3a was further studied by X-ray single-crystal diff ractommetry which showed the presence of dimeric units with μ2-bridging triflate ligands and three-coordinate silver atoms with a planar T-shaped coordination geometry. Reaction of 4-chloro-1,3-bis(2,6-dimethylphenyl)-1,3,2-diazaphospholenium triflate (4[CF3SO3]) with 2a, c affords equilibrium mixtures whose 31P- and 109Ag-NMR spectra suggested the presence of silver complexes 5a, c with constitutions similar to those of 3a, c besides unreacted cation 4. No reaction was observed between 4[CF3SO3] and 2b. A common mechanism accounting for the different outcome of the individual reactions will be discussed.

Notes: The reaction of 2,5-dihydro-4,5,5-trimethyl-2,2-di-2-pyridyl-imidazole-1-oxyl (L) with AgSbF6 gives the complex [Ag2L2]2+[SbF6-]2 which was characterized by X-ray diffraction. - The complex (a biradical) forms a four-membered ring with two Ag(I) ions and two imine nitrogen atoms of the imidazolines with a relatively short Ag - Ag distance [2.839(2) Å]. Magnetic measurements indicate that two nitroxide radicals are slightly coupled.

Notes: The crown thioether 3 with the novel diisopropylidene building block was synthesized by an S′N cyclization reaction of 2,7-dichloro-2,7-dimethylocta-3,5-diyne (1) with 3-thia-pentane-1,5-dithiol (2). Ligand 3 shows all the sulfur centers in exodentate positions. Reaction of 3 with Ag1 triflate and triphenylphosphane yielded the tetrahedral complex 4, which shows unique spectroscopic data in solution. Crystallization furnished two different crystal forms (4a and 4b). Both are different conformers which are stable in the solid state. 4a exhibits a crown-like structure of the thioether ligand with cisoid S—C—C—S chains. To our knowledge 4b is the first silver(1) complex with a crown thioether retaining the tran-soid S—C—C—S conformation in the metal complex.

Notes: Cationic metallacyclic carbene complexes of iron and cobalt bearing a terminal η3-allyl ligand are susceptible to nucleophilic attack at different sites depending on the particular set of substituents, the central metal fragment, and the nucleophile. Attack of enolates, cuprates, acetylides, or heteroatom nucleophiles like phosphanes at the metallacyclic perimeter of the iron complexes 18 provides an easy access to unsaturated organic products like 1,2- or 1,3-dienes, δ-lactones, and functionalized cyclopentenones through novel rearrangement or cascade pathways. Synthetic applications are described; factors governing reactivity/selectivity are discussed; X-ray analytical structures of novel metallacycles are provided.

Notes: The outcome of reactions of bis(phosphonio)isophosphindolide salts 1[X] and 6[X] (X- = Cl-, Br-, CF3SO3-) with silver salts AgY (Y- = CF3SO3-, CF3CO2-, CH3CO2-, 1/2 SO4-) depends strongly on the available anions X, Y. If X-, Y- = CF3SO3-, both mononuclear and dinuclear silver complexes are formed which exhibit either μ1,μ1(P) or μ2,η1(P) coordination of the cations 1, 6 to one or to both metals. In solution, dynamic equilibria between both types of products and free 1, 6 were detected by 31P-NMR spectroscopy. Mononuclear (4a, 7) and dinuclear (5a, 8) complexes were isolated as solvates with CHCl3 or THF. If X-, Y- = CF3CO2, only equilibrium mixtures between the free ligands and silver complexes and no isolable products were obtained. 31P-NMR investigations revealed a preference for the formation of dinuclear complexes. Anion metathesis and precipitation of AgX were observed for X- = Cl-, Br-. No coordination of 1, 6 to Ag+ took place in the case of Y- = CH3CO2-, SO42-. The formed complexes were characterised in solution by 31P- and in part by 109Ag-NMR spectroscopy. Complexes 7, 8 were further studied by single crystal X-ray diffraction which revealed the presence of a THF molecule coordinated to silver in both cases. The μ2-coordinated cation 1 is the only bridging ligand in 8, whereas the presence of additional μ2-CF3CO2 ligands was deduced from the results of 31P,31P EXSY measurements in the case of the trifluoroacetato complexes.

Notes: The present article gives an account of the synthesis and structure as well as the spectroscopic and chemical properties of arsaalkenes R1As=CR2R3 and arsaalkynes RC≡As. Arsaalkenes are significantly less stable and more reactive than the corresponding phosphaalkenes. Only one kinetically stabilized arsaalkyne has been described so far.

Notes: tetrahedra-Tetrakis[tris(trimethylsilyl)methyl]tetraindane(4) (1) reacts with octacarbonyldicobalt to yield two products, depending on the stoichiometric ratio of the starting compounds: By replacement of one bridging carbonyl group a dicobalt monoindium derivative 2 is formed, which contains a Co—Co bond [256.81(5) pm] bridged by one carbonyl and one monoalkylindium group. While 2 is a monomer in benzene solutions, it dimerizes in the solid state by an interaction of the oxygen atom of the bridging carbonyl group to the coordinatively unsaturated In atom of a second molecule across a center of symmetry. Another compound (3) is formed by the replacement of both bridging carbonyl ligands, which exhibits a strongly distorted Co2In2 tetrahedron with normal Co—In bond lengths of 253.44(6) pm, but long Co—Co [280.14(6) pm] and In—In distances [336.18(6) pm].

Notes: Cyclobutene, bicyclobutane, and 1,3-butadiene are valence isomers within the concept of the Woodward-Hoffman rules. According to thermochemical considerations and in agreement with energy optimized quantum-chemical calculations at the ab initio RHF and MP2/6-31G(d,p) levels bicyclobutane is the least and 1,3-butadiene the most stable valence isomer. Phosphorus substitution exerts a considerable effect on the relative stabilities of the various valence isomers. Bicyclobutanes containing phosphorus atoms in the bridgehead positions are considerably more stable than the other phosphorus-substituted valence isomers. This conclusion was confirmed by an analysis of the natural bond populations.

Notes: After a brief review of previous work the results of the metathesis reaction between Ni(dme)Br2 and R2P(O)NR′Li [R = tBu, iPr, Ph; R′ = Et, Pr, iPr, (±)-sBu, tBu, tPen, Cy, Ph, (-)-α-methylbenzyl = Mb, 1-adamantyl = Ad] are reported. Complex formation occurred only with lithiated amides of tert-butylphosphinic acid, and bischelates [tBu2P(O)NR′]2Ni were obtained when R′ = sBu, Mb, tPen, Ad (1d - g). With R′ = Et, Pr bischelation was incomplete. Vis spectroscopy showed the paramagnetic compounds 1d - f to be planar in the solid state but tetrahedral in solution. 1g is tetrahedral in both phases. The planar structure of 1f was confirmed by X-ray single-crystal analysis (monoclinic, space group P21/n). The magnetic moments μeff of 1d, e, g are ca. 3.2-3.5 μB in both phases and the Curie-Weiss law is obeyed in the range 293-183 K. The same is valid for dissolved 1f. The μeff values of solid 1f are however, strongly temperature-dependent, varying from 1.38 to 0.55 μB (300-90 K). NMR data (31P, 1H, 13C) are reported. Obviously, a favorable combination of electronic and steric factors of substituents R and R′ produces with ligands [R2P(O)NR′]- the donor quality necessary for bischelation as well as the singular field strength required for the formation of planar paramagnetic species. As the combination of paramagnetism and planarity is bound to the solid state, lattice energy effects may be finally decisive for this unique constellation of tetracoordinated NiII complexes.

Notes: NMR studies of the reaction of complexes of the type (L-L)MoO(O2)2 (L - L= bidentate ligand) with strong Brønsted and Lewis acids prove that protons are transferred preferentially to an η2-peroxo and not to the oxo ligand. This behavior in proton transfer reactions is one critical point of the catalytic activity of such complexes in olefin epoxidation. EH calculations on the model complex (NH3)2MoO(O2)2 support the spectroscopic investigations.

Notes: Tetrakis[bis(trimethylsilyl)methyl]digallane(4) (1) reacts with tert-butyl or aryl=isocyanides [aryl = phenyl, o-methylphenyl, o-methoxyphenyl, p-methoxyphenyl) by a twofold insertion of the central carbon atoms into the Ga-Ga bond and formation of C-C single bonds. 1,4-Diazabutadiene derivatives bound to two R2Ga groups are formed (2-6), which in contrast to an aluminium analog exhibit only weak interactions between the imine nitrogen atoms and the coordinatively unsaturated gallium atoms as indicated by NMR spectroscopy and the long Ga-N distances in the molecular structures of three products: 2 (R = C6H5), 4 (R = o-MeOC6H4), and 6 (R = CMe3).

Notes: Irradiation of methanolic cadmium sulfide suspensions in the presence of Schiff bases and cyclopentene opens an easy access to new γ,δ-unsaturated amines. Their formation can be described as a kind of paired photoelectrolysis induced by the photogenerated electron-hole pair trapped at reactive surface sites of CdS. At the reductive site the imine is converted to an α-aminobenzyl radical by a proton-coupled electron transfer, while at the oxidative site cyclopentene is transformed to the cyclopentenyl radical through deprotonation of the intermediate radical cation. C-C coupling of these radicals affords the addition products. Competitive dimerisation of the radicals produces hydrodimers of the imines and dehydrodimers of the olefin, as demonstrated in the case of 1-phenylcyclohexene. Using optical active imines, we found no significant diastereoselectivity. In the absence of an olefin the alcoholic solvent was added to the imine. The molecular structure of one hydrodimer was resolved by X-ray analysis. When CdS/Pt was used as photocatalyst, hydrolysis products of the imine were formed, suggesting involvement of an intermediate OH radical.

Notes: The complexes [Ln(Ph2pz)3 (DME)2] and [Ln(tBu2pz)3 (DME)] (Ln = La, Nd, Er; Ph2pzH = 3,5-diphenylpyrazole; tBu2pzH = 3,5-di-tert-butylpyrazole; DME = 1,2-dimethoxyethane) have been prepared by reaction of the lanthanoid metal with bis(pentafluorophenyl)mercury and the pyrazole in DME. The molecular structures of [Er(Ph2pz)3 (DME)2] (3) and [Nd(tBu2pz)3 (DME)]∞ (5) have been determined by X-ray diffraction. Complex 3 has nine-coordinate Er with three chelating Ph2pz ligands and one chelating and one η1-bound DME. There is a trigonal prismatic arrangement of the oxygen donors and the centres of the N - N bonds. 5 was found to be a linear polymer with transoid DME ligands bridging Nd(tBu2pz)3 units in a novel manner. The centres of the N - N bonds (which are essentially coplanar with Nd), and the oxygen donor atoms adopt an arrangement intermediate between trigonal-bipyramidal and square-pyramidal [O - Nd - O 153.5(2)°].

Notes: By a variation of the nature of the reagent system conjugate addition to the cross-conjugated steroidal dienone 1 occurs selectively either at C-1 or at the sterically hindered C-5. With Me3Al or Me4AlLi in the presence of catalytic amounts of Cu1 salts, a high regioselectivity (up to 97:3) in favour of position 1 is achieved. Application of ate complexes of aluminium and titanium in the presence of Ni(acac)2 as catalyst, however, leads to a reversal of the regioselectivity in favour of position 5 (up to 11:89). Aluminium and titanium ate complexes are efficient reagents in the Ni(acac)2-catalysed conjugate addition to sterically hindered enones.

Notes: Complexes with Metal-Phosphorus Triple Bonds as Possible Intermediates in the Reactions between Chlorophosphinidenes and Metalates of Various Transition MetalsThe reaction of [{M′(CO)5}2PCl] (M′ = Cr, W) with various metalates ([Cp′Mo(CO)3]-, [Cp * Ni(CO)]-, [Cr2(CO)10]2-) yields the M2P2 tetrahedral complexes [(MLn)2(μ,η2- P2){M′(CO)5}2] (MLn = Cp*Ni, M′= Cr (1), W (2); MLn = Cp′Mo(CO)2, M′ = Cr (4); Cp* = η5-C5Me5, Cp* = η5C5H3tBu2) and the cyclo-P4 compound [{Cr(CO)4}(η4-P4){Cr(CO)5}4] 6. As side products the distorted prismane [(Cp*Ni)2{μ4,η4-(P2-O-P2)}{W(CO)5}2] 3 and the diphosphino-methanone complex [{Cp′Mo(CO)2}2{μ4η2-PC(O)P}-{Cr(CO)5}2] 5 are formed. The complexes are characterised by NMR, IR, MS, and X-ray structure analysis (1-5). Studying the reaction pathway provided evidence of phosphido intermediates of the type [LnM≡P→M′Ln].

Notes: Chiral Tripodal Ligands Bearing a Phosphite Donor Group: Synthesis and Coordination ChemistryThe mechanism of the reaction of epichlorohydrine (H-CH2Cl) (1) with lithium phosphides is analysed. A neighbouring-group mechanism has been found to be the essential driving force in this reaction. Monophosphanyl alcohols such as HOCH(CH2P(Ph)2)(CH2Cl) (2) and epoxides (Ph)2PCH2- (3) are characterized as intermediates. The mechanism leads to a rapid one-pot method for the synthesis of chiral racemic as well as enantiomerically pure bis(phosphanyl) alcohols HOCH(CH2PR2)(CH2PR2′) (4). The resulting bis(phosphanyl) alcohols 4 react easily with X2PCl (X = Cl; Ph; or X2 = 1,2-ethanedioxy-2,2′-biphenyldiyldioxy-) to yield the mixed donor group tripodal ligands X2POCH(CH2PR2)(CH2PR′2) (5, 6) containing both phosphite, phosphinite or phosphorodichloridite and phosphane donor groups. The identity of these compounds were proved by 1H-, 31P- and 13C-NMR spectroscopy, mass spectra, microanalysis as well as X-ray analysis. The coordination capabilities of these novel ligands are demonstrated by the synthesis and characterization of a (cyclooctadiene)rhodium complex {[(5c)Rh(I)COD]PF6} (7) of the ligand 5c, exhibiting the typical hetero-bicyclooctane tripod metal cage of this type of tripod complexes.

Notes: The highly reactive silyl triflates R4-nSi(OSO2CF3)n are valuable materials in organosilicon chemistry. Numerous new triflate derivatives of mono-, oligo-, and polysilanes were prepared by stepwise substitution of trifluoromethylsulfonyl groups for phenyl groups or other leaving groups. Conversions of silyl triflates with nucleophiles proceed regioselectively and, in most cases, quantitatively at low temperatures with short reaction times. Therefore, silyl triflates are suitable reagents for the synthesis and functionalization of linear and cyclic oligosilanes. Novel polycarbosilanes, polysilylalkynes, and polysilylphenylenes, which show a regular alternating arrangement of silylene groups and organic units, were prepared from α,ω-bis[(trifluoromethylsulfonyloxy)silyl]-substituted compounds and dinucleophiles. Branched polysilanes and polysilynes were obtained by reductive coupling of polymeric silyl triflates with potassium-graphite.

Notes: Bis(dichlorosilyl)amine reacts in chloroform solution with 2-picoline to give H3SiCl, H2SiCl2, and HSiCl3, whereas with 3-picoline the two hypervalent silicon compounds H2SiCl2-(3pic)2 and [H2Si(3pic)4]Cl2 · 4 CHCl3 containing hexacoordinated Si atoms are formed. These complexes are in a chemical equilibrium with each other in chloroform solution, from which crystals of [H2Si(3pic)4]Cl2 · 4 CHCl3 could be isolated. The crystal structure of the latter was determined by single-crystal X-ray diffraction. The complex can be regarded as an “contact ion trio” of [H2Si(3pic)4]2+ and two Cl- ions. The N-Si bond lengths, r(Si-N) = 196.9(3) and 197.5(3) pm, are similar to those found in neutral hexacoordinated Si complexes. The data obtained from a 1H1H ROESY experiment suggest that dissolution has no significant impact on the molecular structure of [H2Si(3pic)4]Cl2 · 4 CHCl3.

Notes: The coordination chemistry of the four oxa-crowned derivatives of dithiomaleonitrile mn-12S2O2, mn-15S2O3, mn-18S2O4, and mn-21S2O5 as well as of the acyclic bis(methylthio)maleonitrile mn-S2 with AgI was investigated by X ray structural and spectroscopic methods. The 2:1 complexes (ligand/AgI) [Ag(mn-12S2O2)2]PF6, [1]PF6, [Ag(mn-15S2O3)2]PF6, [2]PF6, and [Ag(mn-S2)2]PF6, [6]PF6, and the 1:1 complexes [Ag(mn-15S2O3)]ClO4, [3]ClO4, [Ag(mn-18S2O4)]PF6, [4]PF6, and [Ag(mn-21S2O5)]PF6 [5]PF6, were obtained with AgPF6 or AgClO4 in MeOH. The stoichiometry of the macrocyclic AgI complexes and the coordination mode of mn-S2On+1 coronands (n = 1-4) is determined by the length of the macrocyclic oligoethylene chain. - The mn-crown dithioethers mn-12S2O2 and mn-15S2O3 form with AgPF6 the new sandwich complexes [Ag(mn-12S2O2)2]PF6, [1]PF6, and [Ag(mn-15S2O3)2]PF6, [2]PF6. [1]PF6 crystallises in the triclinic space group P1. In the centrosymmetric cation [1]+ each mn-12S2O2 ligand is coordinated to the AgI centre in an endo manner via both S atoms and one O atom. The distance of the second O atom of mn-12S2O2 to AgI is somewhat longer than a normal Ag-Oether bond. The overall environment around AgI in [1]+ is that of a distorted cubic S4O4 set of donors. [2]PF6 crystallises in the monoclinic space group C2/c. In the centrosymmetric cation [2]+ silver(I) is planar-coordinated by the four S atoms of both mn-15S2O3 molecules. The six O atoms of both mn-15S2O3 ligands show only long-range interactions to the AgI ion. They surround AgI almost vertically to the planar S4 set of donors in a crown-like manner. - The crystal structures of the 1:1 complexes [Ag(mn-18S2O4)]PF6, [4]PF6, and [Ag(mn-21S2O5)]PF6, [5]PF6, consist of linear chain polymers. [5]PF6 forms an N-bridged chain polymer of endocyclic [Ag(mn-21S2O5)]+ units with S1O4NNitrile coordination at the AgI centre. In the 2:1 complex [Ag(mn-S2)2]PF6, [6]PF6, each mn-S2 acts as a monodentate NNitrile donor. - 13C-NMR studies in nitromethane solution confirm that the AgI ions in the complexes of the mn-crown dithioethers remain coordinated. However, the AgI ion in complex of mn-S2 is decoordinated.

Notes: Metal π Complexes of Benzene Derivatives, 49. - Halfsandwich Complexes of Trimesitylborane Mes3B: Synthesis and Structure of Mes2[B(η6-Mes)Cr(CO)3], MesB[η6-MesCr(CO)3]2, and B[η6-MesCr(CO)3]3. Redox Behavior and Questions of Intramolecular InteractionReactions of trimesitylborane (15) with hexacarbonylchromium (16), under varying conditions of stoichiometry and duration, afford the halfsandwich complexes 15[Cr(CO)3] = 17, 15[Cr(CO)3]2 = 18 and 15[Cr(CO)3]3 = 19, which have been characterized by X-ray structure analysis. As for the free ligand 15, the propeller shape of the complexes 17-19 induces chirality; the respective unit cells contain both enantiomers. The steric demand of the Cr(CO)3 fragments causes significant structural changes of the Mes3B unit: in 17 and 18 the bond lengths B-C are increased and the C-B-C bond angles in the reference plane ER1, which is spanned by the three carbon atoms bonded to boron, deviate from 120°; the largest differences was observed for 18. Coordination of Cr(CO)3 fragments to 15 leads to increased dihedral angles between the reference plane ER1 and the mesityl planes; the values of 50.1° for 15 and 61.8° for 19 are representative. Because of the lower symmetry within 17 and 18, the dihedral angles differ; a maximum of 71.1°, relative to the reference plane, is assumed by the noncoordinated ring of 18. The main objective of the study of 17-19 relates to the question of intermetallic communication between moieties separated by sp2-hybridized boron. According to IR data, interaction between the Cr(CO)3 units appears to be minimal. Cyclovo-Itammetry is more revealing: boron-centered reduction, which occurs at -1.94 V for 15, involves anodic shifts E1/2 (0/-) of + 0.24 ± 0.04 V per Cr(CO)3 unit for 17, 18 and 19. This trend is surprising since with increasing degree of coordination the dihedral angles also increase and, therefore, conjugation between the B(2pz) orbital and the mesitylene π systems decreases. Consequently, the redox shifts reflect competition between conjugative and inductive effects, the latter exceeding the former. Subsequent reduction to the dianions 172- -192- is quasi-reversible at -50°C. Chromium-centered oxidation in the +1 V region yields CV waves that fail to reveal resolved redox splitting δE1/2 between subsequent redox steps. However, based on the current ip(0/-) of one electron reduction, the peak currents for the oxidations of 17, 18 and 19 represent one-, two- and three-electron processes, respectively. Although these waves deviate from ideal reversibility, a gradual shift to more positive potentials and an increase in peak separation is discernible. From these features, the value δE1/2 ≤ 70 mV for subsequent oxidation processes at 18 and 19 may be derived as a crude estimate, attesting to weak interaction between the Cr(CO)3 moieties. The radical anions 15-•, 17-•, 18-• and 19-• were generated electrochemically and studied by means of EPR spectroscopy. The hyperfine coupling constants a(11B) increase in the order 17-• 〈 18-• ≤ 15-• 〈 19-•, which again demonstrates the action of stereoelectronic effects. Proton hyperfine coupling is resolved only for the radical anion 15-• of the free ligand. This implies that for the complex radical anions 17-• -19-•, due to the larger angles between the B(2pz) orbital and the z axes of the mesitylene π systems, conjugation Blarr;mesitylene is diminished. The UV/Vis spectra of 17-19 exhibit MLCT bands, which, relative to (η6-C6H6)Cr(CO)3 (λ = 317 nm), show large bathochrome shifts [λ (17) = 458 nm]. The additional shifts effected by introducing a second and third Cr(CO)3 unit are small however [λ (18) = 491 nm, λ (19) = 516 nm]. The energies ΔEop of the MLCT transitions may be compared to the differences ΔEcv = E1/2 (+/0, metal-centered) - E1/2(0/-, ligand-centered), the quantity δE = ΔEop - ΔEcv representing χout the outer-sphere reorganisation energy. For 17-19, the value δE = 0.18 ± 0.1 eV is thus obtained. Interestingly, for p-Me2NC6H4BMes2 δE = 0.29 eV has been reported, suggesting a similarity between a Me2N substituent and a Cr(CO)3 fragment bound to tris(aryl)borane.

Notes: The [(SePPh2)2N]- ligand 1c forms stable tris(chelates) with the SbIII, BiIII, and InIII ions. The crystal and molecular structures of the resulting compounds 3, 4, and 5 were determined by X-ray diffractometry. The coordination geometry around the metal centers can be described as a distorted octahedron. This feature and the results obtained by comparing the structures with their sulfur and oxygen analogs lead us to conclude that in both SbIII and BiIII compounds the arrangement around the metals suggests a stereochemically nonactive electron lone pair.

Notes: Selenophosphinito complexes (OC)4Mn(η2-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PR21) (2a, b) [R1 = cyc-Hex (a), tBu (b)] are formed by the reaction of BrMn(CO)5 with the phosphane selenides R21HPSe (1a, b) in the presence of the auxiliary base Et(iPr)2N. According to an X-ray structural analysis, 2a crystallizes in the space group \documentclass{article}\pagestyle{empty}\begin{document}$ P\bar 1 $\end{document} with Z = 2. The dimeric complex [(OC)4Mn(μ-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PMe2)]2 (4c) is not obtained in a straightforward way. Compound 4c is only obtained via the intermediate Br(OC)4Mn-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}P(H)Me2 (3c) by HBr elimination with nBuLi. Complex 3c is formed by replacement of carbon monoxide in BrMn(CO)5 by Me2HPSe (1c). A dissociative equilibrium between [(OC)4 Mn(μ-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PMe2)]2 (4c) and the monomeric species (OC)4Mn(\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}2-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PMe2) was not observed. The cyclocotrimerization of the 〉P\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}Se function with the activated alkynes ZC≡CZ [Z = CO2R2; R2 = Me (d), Et (e), iPr (f), cyc-Hex (g)] was successful only in the case of the cyclohexyl derivative 2a to give the selenaphosphamanganabicycloheptadienes 5d - g. An X-ray structural analysis proved that 5d crystallizes in the space group \documentclass{article}\pagestyle{empty}\begin{document}$ P\bar 1 $\end{document} with Z = 2. Under CO pressure 5d was degraded to the selenophene 6.

Notes: The reduction of the complex [(η5-C5H4)-ansa-(η5-C5H4)]TiCl2 with magnesium in the presence of Me3SiC2-SiMe3 in THF at room temperature gives the ansa-titanocone alkyne complex [(η5-C5H4)-ansa-(η5-C5H4)]Ti(η2-Me3SiC2-SiMe3) (ansa = Me2Si-O-SiMe2, 1). The similar pyridine-stabilized zirconium complexes could be obtained by analogous reactions and addition of pyridine: [(η5-C5H4)-ansa-(η5-C5H4)]Zr(L)(η2-Me3SiC2SiMe3) (ansa = Me2Si-O-SiMe2, L = pyridine: 2; ansa = SiMe2, L = pyridine: 3). All complexes were characterized by spectroscopic methods. An X-ray structure determination of complex 3 was conducted, and the data were compared to those of the complexes rac-(EB-HI)Zr(L)(η2-Me3SiC2SiMe3) [L = (S)-(-)-nicotine: 6, EBHI = ethylenebis(tetrahydroindenyl)] and Cp2Zr(py)(Me3SiC2-SiMe3).

Notes: The bisquaternary ammonium ozonides Me3N+(CH2)n +NMe3(O3-)2 with n = 3, 4, 6 (1, 2, 3), Me3N+(CH2)3+NMe3(O3-)2 · 3 NH3 (1a), Me3N+(p-Ph)+NMe3(O3-)2 (4) and Me3N+(p-Ph)+NMe3(O3-)2 · NH3 (4a) were obtained in quantitative yields by cation exchange starting from CsO3. The compounds 1a and 3 have been studied by single crystal X-ray analysis. The influence of C-H…O and N-H…O hydrogen bonds on the bond length and the bond angle of the ozonide anion is discussed; earlier results are included. The difference between the two bond lengths within the O3- ion [137.4(3) pm and 129.5(3) pm] in 1a is unexpectedly large. Thermal stabilities determined by DTA/TG methods range from 24-83°C.

Notes: The molecular zinc hydroxide complex TpCum,MeZn—OH [1, TpCum,Me = tris(3-cumenyl-5-methylpyrazolyl)hydroborate] is a powerful nucleophile. It effects stoichiometric hydrolysis of activated esters RCO—OX and amides RCO—NHX in nonaqueous media. The cleavage products are TpCum,MeZn—OCOR and HOX or H2NX, resp. Two of them (TpCum,MeZn—OCO—CH2-CH2OH resulting from propiolactone and TpCum,MeZnOCO—CF3 resulting from trifluoroacetamide) were characterized by crystal structure determinations.

Notes: The metal complexes (E,E)-[{diethyl 2,2′-[1,2-phenylenebis(iminomethylidyne)]bis[3-oxobutanoato]}(2-)-N,N′,O3,O3′]manganese (Mn1a), [3,3′]-[1,2-phenylenebis(iminomethylidyne)bis(2,4-pentanedionato)(2-)-N,N′,O2,O2′]manganese (Mn1b), and (Z,Z)-[diethyl 3,3′-(1,2-phenylenediimino)bis(2-cyano-2-propenoato)](2-)-N3,N3′,O1,O1′]manganese (Mn1c) were sythesised and the oxygenation of these complexes was investigated by gas volumetry. All complexes except Mn1c are able to take up oxygen but with different magnitudes. The catalytic activity of the Mn, Co, and Fe complexes of the ligands 1a and 1c and (E,E)-[{diethyl 2,2′-[1,2-ethylenebis(iminomethylidyne)]bis[3-oxobutanoato]} (2-)N,N′,O3,O3′] iron (Fe1d) and [diethyl (all-E)-5,14-dihydro-6,17-dimethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine-7,16-dicarboxylato)(2-)-N5,N9,N14,N18]iron (Fe2a) has been compared with respect to the oxidation of hydroquinone by molecular oxygen. The results are interpreted with the aid of electrochemical properties, Lewis acidities, and other relevant factors. However, no simple relationship between the catalytic activity and the other factors could be found.

Notes: The hydroxyalkylation of lithiated 3-[(S)-2-(methoxymethyl)-pyrrolidino]-1,3-diphenylpropene (2) with aldehydes is completely regioselective giving homoaldol adducts in good yields. The simple diastereoselectivity is low with typical ratios ranging between 1:1 and 1:3 with the syn isomer predominating. The induced diastereoselectivity is much higher and is strongly solvent-dependent. The reaction predominantly proceeds according to a metalloretentive mechanism from the si side of the allylic system in THF as well as in TBME. The induced diastereoselectivity obtained by the use of the less solvating TBME is considerably higher than in the strongly solvating THF, selectivities of up to 97% ee being reached.

Notes: The hydridoruthenium(II) complexes [RuHCl(H2)(SbiPr3)3] (2) and [RuH2(H2(SbiPr3)3] (3), containing dihydrogen as ligand, were prepared from [RuCl2(C8H12)]n (1) as the starting material. Compound 3 reacts with CO by displacement of H2 to yield [RuH2(CO)(SbiPr3)3] (4) and with C2H4 to give both [RuH2(C2H4)2(SbiPr3)2] (5) and [RuH2(C2H4)(SbiPr3)3] (6), the latter as the more stable and isolable product. Treatment of 3 with propene leads to the formation of [Ru(η3-C3H5)2] (7) while the reaction of 3 with butadiene affords the pentacoordinated ruthenium(0) compound [Ru(η4-C4H6)2(SbiPr3)] (8). The molecular structure of the bis-(allyl) complex 7 was determined by X-ray crystallography.

Notes: The partially fluorinated cryptands FN2O4 and BenzoFN2O4, which are relatives of the [2.2.1]cryptand, were synthesized in good yields from 1,3-bis(bromomethyl)-2-fluorobenzene and diaza-18-crown-6 or benzodiaza-18-crown-6, respectively. These macrobicyclic ligands form very stable complexes with Ag(I) salts, and it was shown that close fluorinesilver interactions occur in solution as well as in the solid state. Numerous experimental evidence for this is available: NMR competition experiments show that Ag+ complexes of FN2O4 are significantly more stable than those of HN2O4 (the two ligands are identical except that one fluorine atom is replaced by one hydrogen atom in HN2O4); the 1JCF coupling constants of Ag+ · FN2O4 and Ag+ · BenzoFN2O4 are reduced by 10 Hz compared to those of the respective free ligands FN2O4 (1JCF=253 Hz) and BenzoFN2O4. (1JCF=252 Hz). The X-ray crystal structure of Ag+ · FN2O4 revelas short Ag+-F distances [271.4(3) pm]; coupling of the 107,109Ag+ and 19F nuclei is observed in the 19F-NMR spectra (J=24 Hz for Ag+ · FN2O4, J=25 Hz for Ag+ · BenzoFN2O4). The 1H-NMR spectrum of Ag+ ·FN2O4 is very complex and exhibits sixteen unique proton resonances, whose evaluation yielded coupling constants and NOEs, which show that the structure in solution is compatible with the results obtained by the X-ray crystal structure determination.

Notes: The dipeptides Ac-Cys-Val-OH (1a) and Ac-His-Val-OH (1b), H-Gly-Cys-OEt (2a) and H-Val-His-OEt (2b) as well as Z-Asp-Cys-OH (3a) and Z-Asp-His-OH (3b) (Z = benzyloxycarbonyl) were prepared, and their zinc complexation was investigated by potentiometric methods. They have in common that in addition to the cysteine thiolate or the histidine imidazole the second amino acid offers one donor function. The complex stabilities are very close to those of the corresponding difunctional derivatives of the single amino acids cysteine or histidine. This indicates the presence of seven- to ten-membered chelate rings.

Notes: Highly active catalysts for the hydrogenation of CO2 to formic acid in DMSO/NEt3 are formed in situ from [{(cod)Rh(μ-Cl)}2] and various monodentate or bidentate ligands with phosphorus as the donor atom. Formic acid concentrations up to 2.3 · 0.2 mol l-1 can be obtained in less than 6 hours at ambient temperature under a total initial pressure of 40 atm by using rhodium concentrations of 5 · 10-3 mol l-1. The changes in catalytic activities observed upon structural changes of monodentate ligands are discussed in terms of classical ligand parameters like basicity and steric demand of the PR3 group, while with bidentate ligands R2P(CH2)nPR2 the chain length n plays a dominant role for the activity of the catalyst. The effects cannot be explained by a direct impact of the ligand on catalytically active intermediates only, but influences on the formation of these species must also be taken into account.

Notes: Complexes of Halide Ions with 1-Halogen-2-phenylacetylenes. Crystal Structures of PPh4[X(I - C≡C - Ph)4] with X = Cl, Br, I, of PPh4[Br(Br - C≡C - Ph)4], and of NMe4[F(I - C≡C - Ph)2]Herrn Prof. Dr. H. Brunner zum 60. Geburtstag gewidmet.The complexes PPh4[X(I - C≡C - Ph)4] with X = Cl (1), Br (2), I (3), PPh4[Br(Br - C≡C - Ph)4] (4), and NMe4[F(I - C≡C - Ph)2] (5) were prepared from the corresponding salts PPh4X and NMe4F, respectively, with the 1-halogen-2-phenylacetylenes X - C≡C - Ph (X = Br, I) in dichloromethane solutions. 1 - 5 form colourless crystals, which were characterized by vibrational spectroscopy. According to the crystal structure determinations the halide ions in 1 - 4 are coordinated by the halogen atoms of the 1-halogen-2-phenylacetylenes in a tetragonal-pyramidal fashion. The fluoride ion in 5 is only twofold coordinated with a bond angle I - F - I of 110.45°.

Notes: The synthesis of bis(2,3,7,8,12,13,17,18-octaethyl-5-methyl-porphyrinato)cerium(IV) and -zirconium(IV) [M(oemep)2; M = Ce, Zr, respectively] is described. The complexes were characterized by UV/Vis and IR spectroscopy and cyclic volt-ammetry. 1H-NMR spectra of the new cerium and zirconium sandwich complexes show that they exist as a mixture of vicinal and transversal isomers due to the rigid square-antipri-smatic coordination geometry found in metal(IV) bis(porphy-rinates). From the temperature dependence of the 1H-NMR spectra the rotational rigidity of the double-decker system was deduced. In toluene, free rotation of the two porphyrin macrocycles with respect to each other does not occur up to 373 K.