Titanium-Carbon a-Bonded Complexes

Titanium-Carbon a-Bonded Complexes. A full report of the mono- and di-nuclear anionic derivatives of MeTiXj (X = Cl or Br) has now been published, together with a discussion of the structure of MeTiClj in the solid state, and a brief report of both O2 and SO2 insertions into Ti—C bonds. Pb(CH=CH2)4 reacts with TiQ (1 1) to form (CH2=CH)TiQ3. This purple compound is less stable than MeTiCl3 and decomposes rapidly at temperatures above — 30°C however, 1 2 THF and 1 1 dimethoxyethane adducts may be prepared, and these moisture-sensitive green solids are more thermally stable than the parent compound. The observed thermal decomposition products of (CH2=CH)TiCl3, ethylene, butadiene, and a little acetylene, are more consistent with a mechanism involving homolytic fission of the Ti-vinyl bond than with p-elimination. Wolfsberg-Helmholtz calculations have 

Causse, R. Tabacchi, and A. Jacot-Guillarmod, Helv. Chim. Acta, 1972, 55, 1560. 

Transition-metal acetylides react readily with metal carbonyls to form derivatives. Thus (7t-Cp)2Ti(C CPh)2 and Ni(CO)4 afford (22). The oxidative additions of alkyl and acyl halides, RCOCl (R = Me or Ph), to [(7i-Cp)2Ti(CO)2] yield the corresponding [(7i-Cp)2Ti(Cl)C(0)R] compounds, and 9,10-phenanthraquinone affords (23). [(7i-Cp)2TiPh2] and [(7t-Cp)2 Ti(Me)Cl] have been shown to be active hydrogenation catalysts and the n.m.r. spectra of several [(7t-Cp)2TiR2] and [(7i-Cp)2Ti(R)Cl] compounds have been re-investigated and previous interpretations of such data questioned.  

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