Ti−Sn, Zr−Sn, and Hf−Sn Heterodimetallic Complexes: Stabilizing Unsupported Group 4−Group 14 Metal−Metal Bonds

Reaction of the tripodal amido complexes [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 ZrCl] and [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 HfCl] with LiSnPh 3 in toluene yielded the Zr−Sn and Hf−Sn complexes [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 ZrSnPh 3 ] ( 1 ) and [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 HfSnPh 3 ] ( 2 ), while attempts to synthesize the corresponding Ti−Sn complex resulted in the oxidative coupling of the stannate to give Ph 3 Sn−SnPh 3 and unidentified titanium species. More stable group 4−group 14 complexes were obtained by reaction of the triamido stannate complex [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 SnLi(OEt 2 )] with the metallocene dichlorides [Cp 2 MCl 2 ] of all three titanium group metals, giving [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 SnM(η 5 -C 5 H 5 ) 2 (Cl)] (M = Ti, 3; Zr, 4; Hf, 5 ). X-ray diffraction studies of 4 and 5 established Zr−Sn and Hf−Sn bond lengths of 3.02313(17) and 2.9956(3) Å, respectively.