Reactions of (Me₃ECH₂)₃ZrSi(SiMe₃)₃(E = C, Si) with 2,6-Dimethylphenyl Isocyanide. Preferential Isocyanide Insertion into Zr−Silyl Bonds

Abstract

The reactions of alkyl silyl complexes (Me3ECH2)3ZrSi(SiMe3)3 [E = C (1), Si (2)] with 2,6-dimethylphenyl isocyanide (ArNC) have been investigated. The first ArNC was found to insert exclusively into the Zr − Si bond, and the second and third ArNC into the Zr−C bonds in 1 and 2. 1 and 2 react with up to 3 equiv of ArNC to give (Me3ECH2)3Zr{η2-C[Si(SiMe3)3]NAr} [E = C (3), Si (4)], (Me3ECH2)2Zr[η2-C(CH2EMe3)NAr]{η2-C[Si(SiMe3)3]NAr} [E = C (5), Si (6)], and (Me3ECH2)Zr[η2-C(CH2EMe3)NAr]2{η2-C[Si(SiMe3)3]NAr} [E = C (7), Si (8)]. The tri-insertion complexes 7 and 8 are inert to excess ArNC. The structures of 3 and 7 have been determined by X-ray crystallography. In the structure of 3, the α-hydrogen atoms on one neopentyl ligand lie in close contact (av 2.41 Å) with the metal center giving rise to Zr−C−Hα bond angles of 90 and 92°. The crystal structure of the precursor 1 has also been determined.

Multi-insertion Reactions of Isocyanides with Zirconium Amido Silyl Complexes

“…We reported recently that in the reactions of alkyl silyl complexes (Me 3 ECH 2 ) 3 ZrSi(SiMe 3 ) 3 with ArNC, the first isocyanide insertion occurred exclusively into the Zr−Si bonds (Scheme ) . This preferential isocyanide insertion into the Zr−Si bonds in the alkyl silyl system prompted us to study the reactions of the amido analogues (Me 2 N) 3 ZrSiR 3 [SiR 3 = Si(SiMe 3 ) 3 ( 1 ), SiPh 2 Bu t ( 2 )] and (Me 2 N) 2 [(Me 3 Si) 2 N]ZrSi(SiMe 3 ) 3 ( 3 ) with isocyanide.…”

“…This preferential isocyanide insertion into the Zr−Si bonds in the alkyl silyl system prompted us to study the reactions of the amido analogues (Me 2 N) 3 ZrSiR 3 [SiR 3 = Si(SiMe 3 ) 3 ( 1 ), SiPh 2 Bu t ( 2 )] and (Me 2 N) 2 [(Me 3 Si) 2 N]ZrSi(SiMe 3 ) 3 ( 3 ) with isocyanide. Insertions of isocyanides (RNC) into M−C, − M−N, , and M−Si , bonds of early-transition-metal complexes are well documented; however, there are only a few reports of the reactions of isocyanides with metal complexes containing different reactive ligands. 3e,, The reactions of isocyanides with complexes involving both M−Si and M−N bonds, to our knowledge, have not been investigated. Our amido silyl complexes 1 − 3 offer a unique opportunity to observe the direct competition between silyl and amido ligands in the migration step and to study whether silyl or amido ligand migration is preferred.…”

Reactivities of d0 transition metal complexes toward oxygen: Synthetic and mechanistic studies

“…This exchange is similar to the exchange Ta(NMe 2 ) 5 (6) + (Me 2 N) 3 Ta(ONMe 2 ) 2 (8) 2 (Me 2 N) 4 TaO-NMe 2 (7) discussed earlier [12] . Reactions of both (Me 2 N) 4 Ta(SiBu t Ph 2 ) (12) The −Si(SiMe 3 ) 3 group is bulkier than the −SiBu t Ph 2 group, and it may prevent the formation of additional products in the reaction of (Me 2 N) 3 TaSi(SiMe 3 ) 3 (11) with O 2 , yielding just one product [26][27][28][29][30][31][32][33][34][35][36] . In other words, kinetic barriers may have limited the reactivities of bulkier 11 and 12.…”

Preparation, Structure and Reactivity of Et2N(Me3Si)2SiK

“…The reaction of hafnocene dichloride to the red colored (diethylamino)bis(trimethylsilyl)silylhafnocene chloride (6) was possible directly from 2 (Scheme 2). The fact that both silylmetallocenes reacted with 2,6-dimethylphenylisonitrile to give the insertion products [17,22] very easily (Scheme 3) indicates that the amino nitrogen on the silyl group does not block the coordination site on the metal. This assumption was verified by a crystal structure analysis of zirconocene 5, which does not show any interaction between the Zr and N atoms (distance 3.8 Å) ( Figure 4).…”