Early transition-metal compounds with doubly silyl-bridged dicyclopentadienyl ligands

Abstract

In this paper we present a summary of the different types of complexes formed by the group 4 and 6 metáis with ligands resulting from the doubly bridged bis(dirnethylsilyl) dicyclopentadiene [(SiMe2)2(C5H4)2], which were presented in a recent lecture . TiCI4 and MCp'CI3 [M = Ti, Zr; Cp' = C5H5, C5Me5] react with the monolithium salt of the ligand to give mono [(TíCI3){(η s-CsH3)(SiMe2)2(C5H4)}] and mixed dicyclopentadienyl-type [(TiCp'CI2){(η 5- C5H3)(SiMe2)2{C5H4)}] complexes. TiCI4 reacts with the dilithium salt of the ligand to give mixtures of cis- and trans-[(TiCl3)2{(SiMe2)2(η5-C5Hg)2}] dinuclear compounds, which are transformed into their µ-oxo and methyi derivatives by hydrolysis and alkylation, respectively, with MgCIMe. Related cis and trans homodinuclear group 6 metal hydrido-carbonyls [{M(CO)3H}2{(SiMe2)2(η5-C5H3)2}] are prepared by reacting [Mo(CO)3mesitylene] and [W(CO)3(MeCN)3] with [(SiMe2)2(C5H4)2]. The hydrido-carbonyl compounds can be transformed into their anionic tricarbonyl metallate derivatives; neutral nitrosyl, chloro, imido and metal-metal-bonded tricarbonyl species; and cationic carbonyl and related compounds. Reactions of the mixed titanocene complexes [(TiCp'CyKr/5- C5H3)(SiMe2)2(05H4)}] with [Mo(CO)3mesitylene] and [W(CO)3(MeCN)3] provide cis and trans heterodinuclear [{TiCp'Cl2{M(CO)3H} {(SiMe2)2(η5~C5H3)2}] complexos that can be transformed into their chloro and imido derivatives. Reactions of MO4 {M = Ti, Zr) with the dilithium salt of the doubly silyl-bridged dicyclopentadienyl ligand in a 1:1 molar ratio leads to metallocene-type [TiCI2){(SiMe2)2(η5-C5H3)2}] complexes, which react with different alkylating agents to give mono- and dialkyl compounds. The Chemical behavior and thermal stability of these compounds has also been studied.