Activation of the (Trimethylsilyl)tetramethylcyclopentadienyl Ligand in the [C5Me4(SiMe3)]2TiCl2/Mg System, Yielding Intramolecular Si−CH2−Mg and Si−CH2−Ti Bonds. Molecular Structures of {[η5-C5Me4SiMe2(μ-CH2{Mg,Mg})][η5-C5Me4(SiMe3)]TiIII(μ-H)2Mg(THF)}2 and [η5:η1-C5Me4SiMe2CH2][η5-C5Me4(SiMe3)]TiIII

• Published in: Organometallics 1997-09, Vol.16 (19), p.4185-4191
• Main Authors: Horáček, Michal, Hiller, Jörg, Thewalt, Ulf, Polášek, Miroslav, Mach, Karel
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om9701783

The reduction of [C5Me4(SiMe3)]2TiCl2 by excess Mg in THF yields the paramagnetic compound {[η5-C5Me4SiMe2(μ-CH2{Mg,Mg})][η5-C5Me4(SiMe3)]TiIII(μ-H)2Mg(THF)}2 (3). In the presence of Me3SiC⋮CSiMe3 the same system affords the paramagnetic compound [η5:η1-C5Me4SiMe2CH2][η5-C5Me4(SiMe3)]TiIII (4) in 75% yield. The crystal structures of 3 and 4 reveal that one SiMe3 group in each of the compounds has been activated by hydrogen abstraction. In centrosymmetric dimer 3, two titanocene−magnesium hydride-bridged units are held together by two methylene groups which link the two Mg atoms via a two-electron−three-center Mg−C−Mg bond. In the mononuclear 4, a regular Ti−CH2 σ-bond (2.204(5) Å) binds the central Ti atom to the η5:η1-C5Me4SiMe2CH2 ligand.