Khalimon Andrey Yu, Dorogov Konstantin Yu, Churakov Andrei V, Kuzmina Lyudmila G, Lemenovskii Dmitry A, Howard Judith A K, Nikonov Georgii I
Chemistry Department, Moscow State University, Vorob'evy Gory, 119992 Moscow, Russia.
Dalton Trans. 2007 Jun 21(23):2440-9. doi: 10.1039/b618806k.
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.
[WCp2(H)2]和[WCp2(H)(SnMe3)]与叔丁基锂进行一锅反应，随后加入等量的二氯二甲基锗，得到单（锗基）取代的钨茂[WCp2(H)(GeMe2Cl)]（1）和[WCp2(SnMe3)(GeMe2Cl)]（7）。产物与卤化锡在三乙胺存在下反应，得到混合配合物[WCp2(SnR2X)(GeMe2Y)]（X、Y = Cl、Br，R = Me、Et），这些配合物进一步转化为中等稳定性的化合物[WCp2(SnR2H)(GeMe2H)]（R = Me（10）、Et（11））。通过选择性卤化10和11中的Sn-H键，制备了许多不对称的单（卤代）取代锗基/锡基钨茂[WCp2(SnMe2X)(GeMe2H)]（X = Cl（12）、Br（13））和[WCp2(SnEt2Y)(GeMe2H)]（Y = Br（14）、I（15））。对[WCp2(H)(GeMe2Cl)]（1）、[WCp2(SnEt2Br)(GeMe2Cl)]（4）和[WCp2(SnEt2Br)(GeMe2H)]（14）的X射线研究确定了这些化合物的经典结构。对配合物[WCp2(SnMeCl)(GeMe2Cl)]（3）的X射线研究表明，在高度Ge/Sn无序结构中存在配体间的Ge-Cl...Sn-Cl相互作用。对1、4和14的分子参数分析表明，金属孤对电子与E-X键的σ*轨道之间存在负超共轭作用，与氯代取代的配合物相比，溴代取代的配合物中这种作用更强。
