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  • Inorganic Chemistry  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Hydrogen Bonding and Conformational Analysis of Chelate-Stabilized Alkoxopalladium(II) Complexes Derived from Amino Alcohol Ligands (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 35-44 
    Details
    ISSN: 0009-2940
    Keywords: Alkoxopalladium(II) ; Conformational analysis ; Hydrogen bonding ; Two-dimensional and cage structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of palladium acetate with two equivalents of di- and triethanolamines RN(CH2CH2OH)2 in the presence of a base affords the new chelate-stabilized alkoxo Pd(II) complexes [Pd(OCH2CH2N(R)CH2CH2OH)2] [R = Me (1), Et (2), n-Bu (3), benzyl (4) or CH2CH2OH (5)]. These N,O-ligated complexes are isolated in high yield as yellow, crystalline solids and are thermally stable despite the presence of several β-hydrogen atoms in the ligand system. Both complexes possess a square-planar palladium coordination geometry with the two oxygen atoms positioned mutually trans. The most notable difference in the molecular structures is that 1 forms a two dimensional network of intermolecular O-H≡O hydrogen bonds, whereas 5 forms intramolecular O-H⃛O hydrogen bonds, which cage the palladium center. In solution 1-4 exist as a diastereoisomeric mixture (a racemic enantiomeric pair SNSN, RNRN and a mesomeric form RNSN) in a 1:1 molar ratio, and this ratio is independent of temperature in nonalcoholic solvents, When complexes 1-4 are dissolved in protic solvents (e.g. MeOH) the diastereomeric excess is temperature-dependent due to an exchange process between the meso diastereoisomer and the (racemic) enantiomeric pair. Thermodynamic parameters for this process in a mixture of MeOH-toluene have been determined with NMR and show this process to be influenced by the steric nature of the alkyl substituent (R) on nitrogen. A conformational analysis based on 1H-NMR coupling constants within the N,O-chelate ring of complexes 1-4 provides details on the solution structure of the ring in both diastereoisomers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300106
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  • 2
    Electronic Resource
    Electronic Resource
    Four-Membered 1,8-Naphthalenediyl Transition Metallacycles (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1851-1856 
    Details
    ISSN: 0009-2940
    Keywords: Grignard reagents, 1,3-di- ; Titanocene ; Zirconocene ; Platinum, complexes of ; Rhodium, complexes of ; Iridium, complexes of ; Metallacycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five 1,8-naphthalenediyl transition metal compounds 2 were prepared by treating either 1,8-naphthalenediylmagnesium (1) or 1,8-dilithionaphthalene with the appropriate transition metal dichloride LnMCl2: LnM = Cp2Ti (2a), (PEt3)2Pt (2b), Cp* PPh3Rh (2c), Cp* PPh3Ir (2d), or Cp*2Zr (2e). The resulting metallacycles were characterized by NMR and mass spectrometry. X-ray crystal structure analyses were performed for (1,8-naphthalenediyl)titanocene (2a) and (1,8-naphthalenediyl)bis(triethylphosphane)platinum (2b). Despite the strain induced by the four-membered metal-containing rings, the naphthalene units show remarkably small distortions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271006
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and Characterization of β-Phosphaenones An Investigation on the Conjugative Properties of the P=C Bond (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 465-476 
    Details
    ISSN: 0009-2940
    Keywords: Phosphaalkenes, C-halo, C-metal ; Phosphaacrylic acid ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermally and air-stable β-phosphaenones were synthesized by functionalization of Mes*P=CCl2 (1; Mes* = supermesityl = 2,4,6-tri-tert-butylphenyl). At low temperature, 1 was lithiated by halogen-metal exchange with n-butyllithium to give the phosphanylidene carbenoid (Z)-Mes*P=C(Cl)Li [(Z)-2] which reacted with acid chlorides to furnish the C-carbonyl-substituted phosphaalkenes (Z)-Mes*P=C(Cl)R (3: P = COtBu; 4: R = COPh; 5: R = COOEt). The reaction of (Z)-2 with carbon dioxide furnished the carboxylate 6, which was converted by treatment with pivaloyl chloride or trimethylsilyl chloride into the phosphaalkenes 7 and 8 functionalized at the carbon atom by an anhydride or a trimethylsilyl ester function, respectively. Acidification of 6 or hydrolysis of 8 with water in chloroform solution afforded the novel carboxylic acid (Z)-Mes*P=C(Cl)COOH (9). Spectroscopic investigations (NMR, UV, IR) of 3-9 and the X-ray structures of 3 and 4 are presented. Based on these properties and on theoretical calculations, the occurrence of conjugation in the β-phosphaenone system is discussed and compared with the well-known conjugation in normal enones.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280506
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