Monometallic, homo-, and hetero-bimetallic complexes of a siloxy-bis(phosphinimide) ligand

Abstract

Deprotonation of Me3SiNP(t-Bu)2Me with BuLi generates [Me3SiNP(t-Bu)2CH2Li] (1), which reacts with (Me2SiCl)2O to give the new siloxyl-bis(phosphinimine) ligand [Me3SiNP(t-Bu)2CH2SiMe2]2O (2). This ligand reacts with 1 or 2 equiv. of CpTiCl3 to give [CpTiCl2NP(t-Bu)2CH2SiMe2OCH2SiMe2P(t-Bu)2NSiMe3] (3) and [CpTiCl2NP(t-Bu)2CH2SiMe2]2O (4), similar to the species [CpNbCl3NP(t-Bu)2CH2SiMe2]2O (5) and [CpTiCl2NP(t-Bu)2(µ-O-(CH2SiMe2)2)- P(t-Bu)2NCpNbCl3] (6). Subsequent alkylations of these metal-halide derivatives afforded the analogous permethylated analogs 7–10, respectively. Reaction of 8 with B(C6F5)3 generates [(CpTiMe2NP(t-Bu)2CH2SiMe2)(CpTiMeNP(t-Bu)2CH2SiMe2)O][MeB(C6F5)] (11). Benzylation of 4 give the species [CpTiBz2NP(t-Bu)2CH2SiMe2]2O (12), which reacts subsequently with NC(2,6-Me2C6H3) to give a 1:1 mixture of the diastereoisomers of [CpTiBz(N=C(CH2Ph)(2,6-Me2C6H3))NP(t-Bu)2CH2SiMe2]2O 13a and 13b. These synthetic routes are described and the implications considered. X-ray structural data for compounds 2, 4, 8, and 10 are reported.Key words: phosphinimide ligands, bimetallic species, heterobimetallic compounds.