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  • 1
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 2209-2214 
    ISSN: 1434-1948
    Schlagwort(e): Aluminium ; Amides ; Calcium ; Metallacycles ; Phosphorus ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Treatment of calcium bis[bis(trimethylsilyl)amide] with two equivalents of tris(trimethylsilylmethyl)alane yields (Me3SiCH2)2Al-N(SiMe3)2 (1) and the dimer [(Me3Si)2N-Ca(μ-CH2SiMe3)2Al(CH2SiMe3)2]2 (2). The five-coordinate bridging carbon atoms show Ca-C bond lengths of 264 and 268 pm. A similar reaction with calcium bis[bis(trimethylsilyl)phosphanide] gives the dimer [(Me3SiCH2)2Al-P(SiMe3)2]2 (3) with crystallographic C2 symmetry. A calcium-containing species is not isolable, however, in the presence of DME - ether cleavage reactions and the formation of the centrosymmetric dimer [(Me3SiCH2)2Al-OCH2CH2OMe]2 (4) are observed. The central moiety is an Al2O2 cycle with fivefold coordinated aluminium centers.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 2215-2220 
    ISSN: 1434-1948
    Schlagwort(e): Magnesium ; Metalation ; Phosphorus ; Polyhedra ; X-ray structures ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The magnesiation of triisopropylsilylphosphane with dibutylmagnesium in toluene yields the octanuclear complex [Mg8(PSiiPr3)6{P(H)SiiPr3}4] (1) which consists of MgPSiiPr3 units forming a hexagonal Mg6P6 prism, with two opposite Mg2P2 moieties capped by additional Mg[P(H)SiiPr3]2 groups. If a small amount of THF is present during the metalation reaction [(THF)4Mg6(PSiiPr3)6] (2) also containing a hexagonal Mg6P6 prism can be isolated. The magnesiation of H2P-SiiPr3 in tetrahydrofuran leads to the formation of the tetrameric complex [(THF)MgPSiiPr3]4(3) with a slightly distorted Mg4P4 cubane-like structure.The structures depend strongly on the steric strain caused by the trialkylsilyl substituents and the neutral coligands at the magnesium center. The highest steric strain, which is induced by coordination to every magnesium atom, leads to the smallest MgnPn polyhedron - the central Mg4P4 heterocubane moiety. In compounds 1 and 2 the hexagonal Mg6P6 prism is formed, however, with reduced steric strain as observed for 2 where the Mg-P bond lengths become more similar.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 517-521 
    ISSN: 1434-1948
    Schlagwort(e): Bis(silyl)phosphanes ; Magnesium ; NMR spectroscopy ; Oligomers ; Phosphorus ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The metathesis reaction of (dme)LiPH2 and chlorodiisopropylsilane yields HP(SiHiPr2)2 (1) and P(SiHiPr2)3 (2). The metalation of 1 by n/sec-dibutylmagnesium in heptane leads to the formation of dimeric magnesium bis[bis(diisopropylsilyl)phosphanide] [(3)2]. A toluene solution of magnesium bis[bis(trimethylsilyl)phosphanide] (4) shows a dimer-trimer equilibrium in the 31P{1H}-NMR spectrum at -40°C with an increasing amount of the dimer with increasing temperature. A molecular mass determination by freezing-point depression in benzene yields a value of 516 g·mol-1, which lies between a monomeric and a dimeric molecule. Cooling of the toluene solution to -30°C leads to the precipitation of single crystals of monoclinic {(Me3Si)2P-Mg[μ-P(SiMe3)2]2}2Mg [(4)3].
    Materialart: Digitale Medien
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  • 4
    ISSN: 1434-1948
    Schlagwort(e): Hydrogen bonds ; Indium ; Lithium ; Nitrogen heterocycles ; Zinc ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The lithiation of 2,5-di(tert-butyl)pyrrole (1) yields bis(tetrahydrofuran)lithium 2,5-di(tert-butyl)pyrrolide (2), which is monomeric in solution as well as in the solid state. Due to the coordination number of three for the lithium atom, short Li-O and Li-N bond lengths of 193 pm are observed. The metathesis reaction of 2 with tris(trimethylsilyl)-methylzinc chloride (3) gives colorless bis[tris(trimethyl-silyl)methylzinc] chloride 2,5-di(tert-butyl)pyrrolide (4). The pyrrolide ligand and the chlorine atom bridge the zinc atoms. One of the zinc atoms is bonded to the nitrogen atom of the pyrrolide substituent, while the other bonds to the opposite C-C bond. At 215 pm, the Zn-N bond is very long compared to those in alkylzinc amides, whereas the Zn-C distances lie in the range of Zn-C bond lengths found between zinc and η5-bonded cyclopentadienide ligands. The molecular structures of 1 and of the low-melting THF adduct 1·thf show a similar 2,5-di(tert-butyl)pyrrole molecule, but in the latter case a weak N-H···O bond is observed (N-H 97 pm, O···H 199 pm).
    Materialart: Digitale Medien
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  • 5
    ISSN: 1434-1948
    Schlagwort(e): Arsenic ; Barium ; Calcium ; Metalations ; NMR spectroscopy ; Phosphorus ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Metalation of triisopropylsilylphosphane with bis(tetrahydrofuran-O)calcium bis[bis(trimethylsilyl)amide] in tetrahydropyran (thp) in a molar ratio of 3:2 yields (Me3Si)2NCa[μ-P(H)SiiPr3]3Ca(thp)3 (1) containing a trigonal-bipyramidal Ca2P3 core, the metal atoms occupying apical positions. Reaction of two equivalents of triisopropylsilylphosphane or -arsane with bis(tetrahydrofuran-O)barium bis[bis(trimethylsilyl)amide] in tetrahydrofuran gives the corresponding bis(phosphanide) 2 and bis(arsanide) 3, compounds of the type (thf)3Ba[μ-E(H)SiiPr3]Ba(thf)2E(H)SiiPr3 with E = P, As. The equimolar reaction of (tri-tert-butylsilyl)phosphane with (thf)2Ba[N(SiMe3)2]2 in toluene yields heteroleptic dimeric (thf)2Ba[N(SiMe3)2][P(H)SitBu3] (4). Addition of a further equivalent of H2PSitBu3 leads to the formation of homoleptic (thf)nBa[P(H)SitBu3]2 (5). Dissolution of the latter in aromatic hydrocarbons leads to the elimination of H2PSitBu3, yielding dimeric (thf)Ba3(PSitBu3)2[P(H)SitBu3]2 (6). The inner core of 6 consists of the tetramer (BaPSitBu3)4 based on a Ba4P4 heterocubane unit, two opposite faces being capped with (thf)Ba[P(H)SitBu3]2 molecules.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1434-1948
    Schlagwort(e): Cyclopentadienes ; Magnesium ; Metalations ; NMR spectroscopy ; Sandwich complexes ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of n/sec-dibutyl magnesium with 6-methyl-6-phenyl- and 6,6-dicyclopropylfulvene gives the β-hydride transfer products 1,1′-bis(1-phenylethyl)- and 1,1′-bis-(dicyclopropylmethyl)magnesocene, respectively. The latter crystallizes in the eclipsed conformation, whereas the first one shows an anti conformation in the solid state. Dimethyl-magnesium deprotonates 6-methyl-6-phenylfulvene with formation of 1,1′-bis(1-phenylethen-1-yl)magnesocene, which decomposes upon isolation. The deprotonation of 6,6-dicyclopropylfulvene with MgMe2 in thf solution yields [bis(tetrahydrofuran-O)][iro{cyclopropane-1,2′(1′-η5-cyclopentadienyl-1′,3′,3′-tricyclopropyl-1′,2′,3′,3a′-tetrahydropentalene)}-3a′-6′-η2-enyl]magnesium. In the absence of β-hydrogen atoms at the organometallic reagent as well as at the fulvene the addition reaction is the only possible reaction pathway. Thus, one Mg-C bond of MgMe2 adds to tetramethylfulvene to give quantitatively dimeric methylmagnesium ethyltetramethylcyclopentadienide. The bridging methyl groups are sterically shielded against further attack of the fulvene.
    Materialart: Digitale Medien
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  • 7
    ISSN: 0009-2940
    Schlagwort(e): Lithium ; Zine ; Dibenzylzinc ; Tmeda complexes ; Heteroleptic alkylzinc amide ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of lithium phenyl(trimethylsilyl)methanide with phenyl(trimethylsilyl)methylzinc chloride-tmeda in the presence of tmeda yields the addition product, a bis(tmeda)-lithium dialkylchlorozincate. The elimination of lithium chloride leads to the formation of a tmeda adduct of bis[phenyl-(trimethylsilyl)methyl]zinc. The metathesis reaction of phenyl(trimethylsilyl)methylzinc chloride-tmeda with lithium tris(trimethylsilyl)silylamide allows the isolation of the corresponding heteroleptic tmeda complex of an alkylzinc amide. The metalation of phenyl(trimethylstannyl)methane with butyllithium yields the transmetalation product benzyllithium. From the metathesis reaction of this lithium base with anhydrous zinc(II) chloride in the presence of tmeda, the tmeda adduct of dibenzylzinc crystallizes. The molecular structures of (tmeda)Li—CH(GeMe3)Ph, (tmeda)Zn(CH2Ph)2, (tmeda)Zn[CH(SiMe3)Ph]2, and (tmeda)Zn[CH(SiMe3)-Ph[N(H)Si(SiMe3)3 are reported. Whereas lithium bonds in an η3-fashion, the zinc atom forms a σ(Zn—C) bond. The extremely wide Zn—N—Si angle in (tmeda)Zn[CH(SiMe3)-Ph[N(H)Si(SiMe3)3 of 157° is remarkable.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 8
    ISSN: 0009-2940
    Schlagwort(e): Phosphanes ; Bis(silyl)phosphanes ; Tris(silyl)phosphanes ; Phosphanides ; Barium bis(phosphanide) ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Barium bis[bis(trimethylsily)amide] metalates bis(isopropyldimethylsilyl)phosphane (1) to yield nearly quantitatively the corresponding barium bis[bis(isopropyldimethylsilyl)phosphanide] (3). This compound shows a temperature-dependent monomer-dimer equilibrium in toluene solution. Both the isomers were characterized by X-ray crystal structure analyses. The monomeric derivatives precipitate as a tetrakis(tetrahydrofuran) complex with a P-Ba-P bond angle of 139.9°. The barium atoms of the monocyclic, centrosymmetric dimer are pentacoordinated by two tetrahydrofuran molecules, one terminal and two bridging phosphanide ligands. The endo- and exocyclic Ba-P distances with values of 332 and 316 pm, respectively, lie within the characteristic range.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 379-397 
    ISSN: 0009-2940
    Schlagwort(e): Boranes, amino-, phosphanyl- ; Diphosphadiboretanes ; Triphosphatriborinanes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Aminochlorophosphanylboranes, (R2N)B(Cl)P(SiMe3)2 (1a  -  d) and (R2N)B(Cl)PH2 (2a  -  d), are obtained from elimination reactions between aminochloroboranes and LiP(SiMe3)2 and LiPH2, respectively. Selected reaction chemistry of (i1-Pr2N)B(Cl)P(SiMe3)2] (1a) with NH3, Me3SiN3, Cr(CO)5 · NMe3, and W(CO)5 · NMe3 is described. The azide (i1-Pr2N)B(N3)P(SiMe3)2 (12a) is stable at 25°C; however, thermolysis at 80°C provides a novel six-membered ring compound [(i1-Pr2N)BN(SiMe3)P(SiMe3)]2 (13a). The reaction of (Ph2N)B(Cl)P(SiMe3)2 (1b) with LiP(SiMe3)2 produces the only isolable bis(phosphanyl)borane (5b), while combination of (R2N)B(Cl)Ph2 with LiPH2 · DME yields new diphosphadiboretanes 6 {(R2N)BPH}2 (R2N=i1-Pr2N, Ph2N and tmp=2,2,6,6-tetramethylpiperidino) and triphosphatriborinanes 7 {(R2N)BPH}3 (R2N=(Me3Si)2N, Me2N and Et2N). Two salts, [(i1-Pr2N) DME]2 (8a) and [tmpLi · DME]2 (8c) (DME=ethylene glycol dimethyl ether) are also isolated. The results of molecular structure determinations for [(i1-Pr2N)Bn(SiMe3)P(SiMe3)]2 (13a), [tmpBPH]2 (4c), [tmpBPH]2 · Cr(CO)5 (7c), {[(Me3Si)2N]BPH}3 (4d), {[(Me3Si)2N]BPH}3 · Cr(CO)5 (7d), (Ph2N)B[P(SiMe3)2]2 (5b), and [(i1-Pr2N) · DME]2 (8a) are discussed.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 10
    ISSN: 0044-8249
    Schlagwort(e): Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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