title: Synthesis and structural studies of germyl and germyl/stannyl substituted tungstenocenes.
abstract: One-pot reactions of [WCp2(H)2] and [WCp2(H)(SnMe3)] with "BuLi followed by an equivalent of GeMe2Cl2 afford mono(germyl) substituted tungstenocenes [WCp2(H)(GeMe2Cl)] (1) and [WCp2(SnMe3)(GeMe2Cl)] (7). Reactions of the products with tin halides in the presence NEt3 afford the mixed complexes [WCp2(SnR2X)(GeMe2Y)] (X, Y = Cl, Br, R = Me, Et), which were further converted to moderately stable compounds [WCp2(SnR2H)(GeMe2H)] (R = Me (10), Et (11)). A number of asymmetric mono(halo)-substituted germyl/stannyl tungstenocenes [WCp2(SnMe2X)(GeMe2H)] (X = Cl (12), Br (13)) and [WCp2(SnEt2Y)(GeMe2H)] (Y = Br (14), I (15)) were prepared by selective halogenation of the Sn-H bond in 10 and 11. X-Ray studies of [WCp2(H)(GeMe2Cl)] (1), [WCp2(SnEt2Br)(GeMe2Cl)] (4), and [WCp2(SnEt2Br)(GeMe2H)] (14) established classical structures of these compounds. X-Ray study of complex [WCp2(SnMeCl)(GeMe2Cl)] (3) revealed the presence of interligand Ge-Cl...Sn-Cl interactions in a highly Ge/Sn disordered structure. Analyses of molecular parameters of 1, 4, and 14 suggest the presence of a negative hyperconjugation between metal lone pairs and the sigma*-orbital of the E-X bond, which is stronger in bromo substituted complexes in comparison with chloro substituted ones.
authors.affiliation: Chemistry Department, Moscow State University, Vorob'evy Gory, 119992 Moscow, Russia.
authors.forename: Andrey Yu
authors.initials: AY
authors.lastname: Khalimon
authors.forename: Konstantin Yu
authors.initials: KY
authors.lastname: Dorogov
authors.forename: Andrei V
authors.initials: AV
authors.lastname: Churakov
authors.forename: Lyudmila G
authors.initials: LG
authors.lastname: Kuzmina
authors.forename: Dmitry A
authors.initials: DA
authors.lastname: Lemenovskii
authors.forename: Judith A K
authors.initials: JA
authors.lastname: Howard
authors.forename: Georgii I
authors.initials: GI
authors.lastname: Nikonov