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  • 1
    ISSN: 1434-1948
    Keywords: Alkyne complexes ; Titanium ; Zirconium ; Coordination mode ; Metallacycles ; Cyclopentadienes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of metals, alkyne substituents, Cp substitution and additional ligands on the stability of bridged and unbridged η2-alkyne-titanocene and -zirconocene complexes has been investigated. The reduction of the complex [(η5-C5H4)-SiMe2-(η5-C5H4)]TiCl2 with magnesium in the presence of tolan (PhC2Ph) does not give the expected alkyne-titanocene complex [(η5-C5H4)-SiMe2-(η5-C5H4)]Ti(η2-PhC2Ph) but by coupling of two tolan molecules the corresponding titanacyclopentadiene [(η5-C5H4)-SiMe2-(η5-C5H4)]TiC4Ph4 (1) was obtained. In the analogous reaction with Me3SiC2SiMe3 the stable η2-alkyne complex without additional ligands [(η5-C5H4)-SiMe2-(η5-C5H4)]Ti(η2-Me3SiC2SiMe3) (2) was formed, due to the sterical influence of the alkyne substituents. The compounds without additional ligands (thi)2Ti(η2-PhC2Ph) (3) and (thi)2Ti(η2- Me3SiC2SiMe3) (5) were isolated from the unbridged titanocene complex (thi)2TiCl2 (thi = tetrahydroindenyl). Two equivalents of complex 3 reacted with one equivalent of water to yield the dimeric alkylidene-μ-oxo complex [(thi)2Ti(CPh=CHPh)]2(μ-O) (6). The reaction of the unbridged zirconocene compound (thi)2ZrCl2 gave the alkyne complex (thi)2Zr(THF)(η2-Me3- SiC2SiMe3) (7) which is stabilized by THF. At higher temperature THF was eliminated from the orange complex 7 forming the green complex (thi)2Zr(η2-Me3SiC2SiMe3). This behaviour was investigated in detail using NMR spectroscopy and compared to similar complexes such as Cp2Zr(η2-Me3SiC2SiMe3) (not stable without THF), (ebthi)2Zr(η2-Me3SiC2SiMe3) (ebthi = ethylenebistetrahydroindenyl; stable without THF) and Cp*2Zr(η2-Me3SiC2SiMe3) (Cp* = pentamethyl-Cp, stable without THF). All complexes were characterized by spectroscopic methods. X-ray structural determinations were conducted for the complexes 1, 3 and 7. Compound 3 is the first example of a structurally characterized tolan-titanocene complex without additional ligands.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-8249
    Keywords: Alkinkomplexe ; C-C-Aktivierung ; Octatetraine ; Titan ; Zirconium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 789-794 
    ISSN: 0009-2940
    Keywords: Agostic interactions ; Ligand effects ; Titanium ; Zirconium ; Aminopyridinato ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tris(aminopyridinato) zirconium and ansa-aminopyridinato titanium complexes have been sythesized. The reaction of (TMS-APy)3-Zr-Cl (4-methyl-2-trimethylsilyl-aminopyridine=TMS-APy-H) with trimethylsilylbutadiynyl lithium generated in situ affords (TMS-APy)3—Zr—C≡C—C≡C—TMS (1). (TMS-apy)3-Zr-Me2 (2). Compound 2 shows an agostic interaction of the dimethylamido moiety. The reaction of Ti(NMe,2),4 with silox(Apy-H)21,3-di(4′-picolin-2′-yl-amino)-1,1,3,3-tetraisopropyldisiloxane=silox (APy-H)2] gives rise to silox(Apy)2-Ti-(NMe2)2-Ti-[NMe,2)2 (3). Complex 3 reacts with ε-caprolactam to form a caprolactamato complex (4). X-ray crystal structure analyses of 1, 2, 3 and 4 are reported. The complexes 1, 2, 3 and 4 may be considered to be strained donor-functionalized amido(metal) complexes due to the η2 binding mode of the ligand cores, TMS-APy and silox(APy)2, to meet the requirements of the ancillary coordinated substrates is observed. Thus, aminopyridinato complexes seem to be valuable model compounds for investigations of ligand-substrate communications in early transition metal chemistry.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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