Terminal oxo, sulfido, selenido, and tellurido complexes of zirconium, (.eta.5-C5Me4R)2Zr(E)(NC5H5): comparison of terminal Zr-E single and Zr:E double-bond lengths

Abstract

The series of terminal zirconium chalcogenido complexes ([eta][sup 5]-C[sub 5]Me[sub 4]R)[sub 2]Zr(E)(NC[sub 5]H[sub 5])(E = O, S, Se, Te; R = Me, Et) has been synthesized by the reactions of ([eta][sup 5]-C[sub 5]Me[sub 4]R)[sub 2](CO)[sub 2] with either N[sub 2]O or the elemental chalcogen (E = S,Se,Te) in the presence of NC[sub 5]H[sub 5]. The tellurido complex ([eta][sup 5]-C[sub 5]Me[sub 5])[sub 2]Zr(Te)(NC[sub 5]H[sub 5]) reacts instantaneously with N[sub 2]O to give the oxo derivative ([eta][sup 5]-C[sub 5]Me[sub 5])[sub 2]Zr(O)(NC[sub 5]H[sub 5]). The hydrochalcogenido derivatives ([eta][sup 5]-C[sub 5]Me[sub 5])[sub 2]-Zr(EH) [l brace][eta][sup 1]-OC(Ph)=CH[sub 2][r brace] have been obtained by the reactions of ([eta][sup 5]-C[sub 5]Me[sub 5])[sub 2]Zr(E)(NC[sub 5]H[sub 5]) with PhC(O)CH[sub 3], thus demonstrating the basicity of the chalcogenido ligands in these complexes. The structures of the chalcogenido ([eta][sub 5]-C[sub 5]Me[sub 4]Et)[sub 2]Zr(E)NC[sub 5]H[sub 5] (E = O, S, Se, Te) and hydrochalcogenido ([eta][sup 5]-C[sub 5]Me[sub 5])[sub 2]Zr(EH) [l brace][eta][sup 1]-OC(Ph)=CH[sub 2][r brace] (E = O, S, Se) complexes have been determined by X-ray diffraction, thereby allowing a comparison of Zr-E single and Zr=E double bond lengths to be made for a series of structurally-related compounds. A consideration of the difference in lengths of the M-E single and M=E double bonds,more » with respect to the difference in single and double bond covalent radii of the chalcogens, leads to the conclusion that the double bond covalent radius of zirconium in the [([eta][sup 5]-C[sub 5]R[sub 5])[sub 2]Zr] system is ca. 0.07 [angstrom] shorter than its single bond covalent radius. For the heavier chalcogens (S, Se, and Te), the Zr--E single and Zr=E double bond lengths may be predicted reasonably well on the basis of the sum of the covalent radii of Zr and E. In contrast, both the Zr - O single and double bond lengths are anomalously short. 47 refs., 12 figs., 13 tabs.« less