Structural Analysis of Zincocenes with Substituted Cyclopentadienyl Rings

[EN] New zincocenes [ZnCp'2] (2-5) with substituted cyclopentadienyl ligands C(5)Me(4)H, C(5)Me(4)tBu, C(5)Me(4)SiMe(2)tBu and C(5)Me(4)SiMe(3), respectively, have been prepared by the reaction of ZnCl(2) with the appropriate Cp'-transfer reagent. For a comparative structural study, the known [Zn(C(5)H(4)SiMe(3))(2)] (1), has also been investigated, along with the mixed-ring zincocenes [Zn(C(5)Me(5))(C(5)Me(4)SiMe(3))] (6) and [Zn(C(5)Me(5))(C(5)H(4)SiMe(3))] (7), the last two obtained by conproportionation of [Zn(C(5)Me(5))(2)] with 5 or 1, as appropriate. All new compounds were characterised by NMR spectroscopy, and by X-ray methods, with the exception of 7, which yields a side-product (C) upon attempted crystallisation. Compounds 5 and 6 were also investigated by (13)C CPMAS NMR spectroscopy. Zincocenes 1 and 2 have infinite chain structures with bridging Cp' ligands, while 3 and 4 exhibit slipped-sandwich geometries. Compounds 5 and 6 have rigid, eta(5)/eta(1)(sigma) structures, in which the monohapto C(5)Me(4)SiMe(3) ligand is bound to zinc through the silyl-bearing carbon atom. forming a Zn-C bond of comparable strength to the Zn-Me bond in ZnMe(2). Zincocene 5 has dynamic behaviour in solution, but a rigid structure in the solid state, as revealed by (13)C CPMAS NMR Studies, whereas for 6 the different nature of the Cp' ligands and of the ring substituents of the eta(1)-Cp' group (Me and SiMe(3)) have permitted observation for the first time of the rigid eta(5)/eta(1) solution structure. Iminoacyl compounds of composition [Zn(eta(5)-C(5)Me(4)R)(eta(1)-C(NXyl)C(5)Me(4)R)] resulting from the reactions of sonic of the above zincocenes and CNXyl (Xyl=2,6-dimethylphenylisocyanide) have also been obtained and characterised.Financial support front the Spanish Ministerio de Educacion y Ciencia (MEC) (project CTQ2007-62814 and Consolider-Ingenio 2010 CSD2007-00006) and the Junta Lie Andalucia (project FQM672) is gratefully acknowledged (FEDER support). I.R. thanks the Ministry of Education for a research grant. DA.R.J. thanks the sixth framework program of the E.U.. for a MC fellowship. A.R. and R.F. thank the MEC/Universidad de Sevilla fora Ramon y Cajal contract.Fernandez, R.; Grirrane, A.; Resa, I.; Rodriguez, A.; Carmona, E.; Alvarez, E.; Gutierrez-Puebla, E.... (2009). Structural Analysis of Zincocenes with Substituted Cyclopentadienyl Rings. Chemistry - A European Journal. 15(4):924-935. doi:10.1002/chem.200801917S92493515