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  • 1
    Electronic Resource
    Electronic Resource
    Preparation and X-ray Crystal Structure of the First Trimeric Nickel Thiosemicarbazone Complex: The First Example of Oligomerization by both Ni—O—Ni and Ni—S—Ni Bridging (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1421-1423 
    Details
    ISSN: 0009-2940
    Keywords: Nickel cluster ; Nickel complex ; Thioamide ; Thiosemicarbazone ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monomeric nickel(II) thiosemicarbazone complexes are an attractive new class of homogeneous catalysts for the activation of silanes. However, their activity is limited by the formation of inactive oligo- and polymers. The pathway by which aggregation takes place was elucidated by the preparation and X-ray structural analysis of the first trimeric nickel(II) thiosemicarbazone complex. Aggregation was shown to proceed via Ni—O—Ni and Ni—S—Ni bridging, giving rise to both fourfold planar and pseudooctahedral coordination of the nickel ions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961291203
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  • 2
    Electronic Resource
    Electronic Resource
    Tripodliganden mit Neopentangrundgerüst und zwei verschiedenen Donorfunktionen CH3C(CH2PPh2)2(CH2SR): Synthese, Struktur, Redoxchemie und Spektroskopie von Komplexen des Typs tripodM{ortho-(X)(Y)C6H4}Prof. Dr. Jörn Müller zum 60. Geburtstag gewidmet. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1587-1601 
    Details
    ISSN: 0009-2940
    Keywords: Tripod ligands ; Donor groups, mixed (P, S) ; Cobalt sulfur compounds ; Iron sulfur compounds ; Five-coordination of cobalt and iron ; Redox chemistry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tripod Ligands with Neopentane Frame and two Different Donor Groups CH3C(CH2PPh2)2(CH2SR): Synthesis, Structure, Redox Chemistry, and Spectroscopy of the Complexes tripodM{ortho-(X)(Y)C6H4}Prof. Dr. Jörn Müller zum 60. Geburtstag gewidmet.Neopentane-based tripod ligands CH3C(CH2PPh2)2(CH2Z) (Z = SBn, SH, S-) form pentacoordinate compounds [tripodM{ortho(X)(Y)C6H4}]m 1-4 with ortho-phenylene-bridged coligands (X)(Y)C6H4 (X, Y = O-, S-, NH-) and Co(II), Co(III), Fe(II), or Fe(III) as the metal centers. The structures of these complexes are very similar to those observed for CH3C(CH2PPh2)3 as the tripod ligand. The redox potentials, however, for the corresponding one-electron oxidation and reduction processes are highly affected by the change in the tripod donor groups. Both potentials are shifted by a maximum of 700 mV upon replacement of a PPh2 donor group by a sulfur-centered donor with the difference between the potential of the oxidation step and the potential of the reduction step staying almost constant for the whole series of compounds. This difference of around 1.7 eV nicely corresponds to the energy of the HOMO-LUMO chargetransfer bands observed around 2 eV for all of the compounds. It may be inferred therefore that both observations (electron spectroscopy and cyclic voltammetry) refer in a similar way to the HOMO-LUMO gap of the compounds. It is shown that the formation of [tripodCo(III){ortho-(NH)2C6H4}]+(BF4-) from ortho-phenylenediamine as the source of the coligand involves precoordination of the amine ligand followed by deprotonation of the coordinated ligand. The capability of the tripodCo(II) template to form five-coordinate compounds with diamines is further corroborated by the characterization of [tripodCo(en)]2+ (52+). In addition to the standard analytical data, EPR, UV/Vis, cyclovoltammetric data and X-ray structure analyses are presented where appropriate.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961291229
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  • 3
    Electronic Resource
    Electronic Resource
    Tripod Ligands Containing a Mixed P/N/S Doner Set: Synthesis and Coordination Chemistry (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1279-1294 
    Details
    ISSN: 0009-2940
    Keywords: Tripodal ligands ; Aminolytic cleavage of oxetanes ; Tripod molybdenum compounds ; Mixed donor set ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of neopentane-based tripod ligands CH3C(CH2X)(CH2Y)(CH2Z( 3 (X = NR2, NHR; Y = PR2; Z = PR2, SR, S-) in a convergent manner is described. The procedure is based on the aminolytic cleavage of functionalized oxetanes CH3C(CH2OCH2)CH2R 1 by primary or secondary amines, leading to functionalized amino alcohols CH3C(CH2NHR)(CH2OH)(CH2R) or CH3C(CH2NR2)-(CH2OH)(CH2R) 2. The appropriate activation of the R (e.g. OR) and OH groups present in 2 allows for substitution vs. SR or PR2 donor functions. Depending on the nature of the groups present in each reaction step, various protection and groups present in each reaction step, various protection and deprotection steps have to be taken in the course of this type of preparation of the tripod ligands 3. By reaction with (CH3CN)3Mo(CO)3, ligands 3 form Mo(CO)4 derivatives 4 or Mo(CO)3 derivatives 5, depending on the reaction conditions. In compounds 4, the ligands are coordinated in a bidentate mode with the soft donor atoms (P, S) coordinated and the hard donor function playing the role of the dangling arm. In the trihapto bonding mode present in 5, all three donor functions, two soft (P, S) and one hard (NHR′, NR′2), are coordinated. The two types of coordination compounds may be interconverted: 4e (X = NMe2′ Y = PPh2, Z = SiPr) with a non-coordinating CH2NMe2 group is transformed into 5c upon photolytic decarbonylation. Under 1 bar CO at 20°C, 5c reverts to 4e. X-ray structure analysis of a series of compounds of types 4 and 5 reveals characteristics of the relevant conformational patterns. All compounds have been fully characterized by the standard analytical techniques (NMR, MS), as well as elemental analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300917
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  • 4
    Electronic Resource
    Electronic Resource
    Divalent Tin and Lead Compounds EX2 Acting as Bridging Ligands in [{(CO)5M}2EX2]2- (E = Sn, Pb; M = Cr, Mo, W): Preparation and PropertiesDedicated to Professor G. E. Herberich on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 687-699 
    Details
    ISSN: 0009-2940
    Keywords: Tin ; Lead ; 119Sn NMR ; Salt metathesis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of Na2[M2(CO) 10] (M = Cr, Mo, W) with SnHal2 (Hal = Cl, Br) is a well established procedure for the synthesis of anions of type A, [{(CO)5M)SnHal3]-. Conditions are described which, for the same type of procedure, result in the additional formation of dianions of type B, [{(CO)5M}2SnHal2]2-. Procedures for separating these two types of anions in the form of their stable [Ph4P]+ or [nBu4N]+ salts by appropriate salt metathesis are presented. The structures of theses species have been characterized by X-ray analysis of three salts containing type A anions and two salts containing type B anions. The reactivity of the type B salts containing the bulky cations [Ph4P]+ or [nBu4N]+, respectively, is remarkably low; the salts are, however, transformed into highly reactive sodium salts by further metathesis with Na[BPh4]. In such salts the halide substitutents are easily exchanged as shown by the synthesis of ]})CO(5Cr}2oxinato]- (4)- from [Na-(THF)x]2[{(CO)5Cr}2SnCl2] and sodium 8-oxoquinolate, Na[C9H6NO]. The structure of the anion, 4 is compared to the structure of [[(CO)5Cr)SnCl2· THF] and sodium 8-oxochinolate. The preparation of the dinuclear anions [{(CO)5Cr}2E(OOCCH3)2]2- (E = Sn, 2g; E = Pb, 3) is accomplished by the reaction of [Ph4P]2[Cr2(CO)10] with the corresponding acetates E(OOCCH3)2. While 2g and 3 are formal analogues of the type-B anions, their structures reveal an asymmetrical η2-coordination of the two acetato ligands, in each case ending up in a 4+2 coordination for the main group centres, instead of the four-coordination observed for [{(CO)5M}2SnHal2]2-, All compounds have been characterized by usual spetroscopic and analytical techniques. X-ray analyses have been performed for selected examples. 119Sn-NMR data are presented for all of the compounds which contain tin-centred ligands.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300604
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  • 5
    Electronic Resource
    Electronic Resource
    Pyrazolate-Based Oligonuclear Copper and Silver Complexes with N/S Coordination SpheresDedicated to Prof. Dr. Gottfried Huttner on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1441-1447 
    Details
    ISSN: 0009-2940
    Keywords: Pyrazolate complexes ; Bridging ligands ; Copper ; Silver ; N,S-Donor Ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of pyrazole-based potential ligands bearing thioether substituents in 3- and 5-positions of the heterocycle was synthesized [3,5-bis(RSCH2)-pyzH R=Ph (1aH), PhCH2 (1bH), iPr (1cH), tBu (1dH)]. These ligands afford oligonuclear Cu1 and Ag1 coordination compounds [LCu]x (2a-c, L = 1a - c) and [LAg]x (3a-d, L = 1a-d), respectively. The single crystal X-ray analysis of 3c shows the presence of trimeric planar arrays of N,N′-bridging pyrazolates and linear coordinated silver ions, with each two of the trinuclear moieties being linked by two unsupported short intermolecular Ag…Ag contacts [3.041(1) Å]. Molecular-weight determinations for 2a (THF) and 3c (toluene) indicate that hexanuclear entities are preserved in solution. Starting from 1bH the CuII complex [(1b)2Cu2](BF4)2 (4) was synthesized. According to an X-ray crystal structure analysis it consists of dinuclear molecules with two bridging pyrazolates, distorted square planar N2S2 coordination spheres for Cu11 and an axially bridging tetrafluoroborate. Magnetic susceptibility data reveal an antiferromagnetic exchange (J = -206 cm-1) that is among the highest found for doubly pyrazolate bridged dicopper(II) complexes, which is rationalized on the basis of the rather symmetric dinuclear core of 4. The irreversibility of the electrochemical reduction and oxidation processes for the CuII and CuI compounds, respectively, is explained by the inability of the respective coordination framework to adapt to different geometric preferences.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301014
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