Multi-insertion reactions of isocyanides with zirconium amido silyl complexes

The reactions of (Me2N)(3)ZrSi(SiMe3)(3) (1), (Me2N)(3)ZrSiPh2But(THF)(0.5) (2), and (Me2N)(2)[(Me3Si)(2)N]ZrSi(SiMe3)(3) (3) with 2,6-dimethylphenyl isocyanide (ArNC) or tert-butyl isocyanide ((BuNC)-N-t) have been investigated. The first ArNC was found to insert exclusively into the Zr-Si bond in complex 3 and, in contrast, into the Zr-N bonds in complex 1. Up to 4 equiv of ArNC react with 1 and 2 to give (Me2N)(2)Zr[Si(SiMe3)(3)][eta(2)-C(NMe2)=NAr] (4), (Me2N)Zr[Si(SiMe3)(3)][eta(2)-C(NMe2)=NAr](2) (5), (Me2N)Zr[eta(2)-C(NMe2)=NAr](2){eta(2)-C[Si(SiMe3)(3)]=NAr} (6), Zr[eta(2)-C(NMe2)=NAr](3) {eta(2)-C[Si(SiMe3)(3)]=NAr} (7), and Zr[eta(2)-C(NMe2)=NAr](3)[eta(2)-C(SiPh2But) =NAr] (8). However, 3 reacts with only 2 equiv of ArNC to yield (Me2N)(2)[(Me3Si)(2)N]Zr{eta(2)-C[Si(SiMe3)(3)]=NAr} (9) and (Me2N) [(Me3Si)(2)N]Zr[eta(2)-C(NMe2)=NAr]{eta(2)-C[Si(SiMe3)(3)]=NAr} (10). Complex 2 was found to react with 2 equiv of ButNC to yield a ketenimine complex (Me2N)(3)Zr[N(Bu-t)C(SiPh2But)=C=NBut] (12). The reactions of Zr(NMe2)(4) with ArNC and (BuNC)-N-t were also studied and gave tetrainsertion products Zr[eta(2)-C(NMe2)=NR](4) [R = Bu-t (13), 2,6-dimethylphenyl (14)]. The structures of 7, 12, 13, and 14 have been determined by X-ray crystallography.