Synthesis, Characterization, and Reactivity of New Heteroleptic Heterobimetallic Alkoxide Derivatives of Tin(II):  X-ray Crystal Structures of [ClSn{M₂(OPrⁱ)₉}]₂ (M = Zr, Hf), [(C₅H₅)Sn{Zr₂(OPrⁱ)₉}], and [(C₅H₅)Pb(μ₂-OBu^t)₂Sn(OBu^t)]

Abstract

The synthesis of new cyclopentadienyl-containing heterobimetallic alkoxides has been accomplished by employing the alkoxide precursors toward cyclopentadienyl reagents (NaCp and (C 5 H 5 )SnCl). The equimolar reactions of anhydrous SnX 2 (X = Cl, I) and KM 2 (OPr i ) 9 (M = Zr, Hf) offer halide heterobimetallic isopropoxides [XSn{M 2 (OPr i ) 9 }] 2 ( 1, M = Hf, X = Cl; 2, M = Hf, X = I; 3, M = Zr, X = Cl) in quantitative yields. Both 1 and 3 react with NaCp in benzene−THF to give (C 5 H 5 )Sn{M 2 (OPr i ) 9 } ( 4, M = Hf; 5, M = Zr). Alternatively, 4 and 5 are conveniently obtained by the equimolar reaction of (C 5 H 5 )SnCl with KM 2 (OPr i ) 9 (M = Zr, Hf). Although the reaction (1:1) of (C 5 H 5 )SnCl with [KGe(OBu t ) 3 ] n affords the expected product (C 5 H 5 )Sn(μ 2 -OBu t ) 2 Ge(OBu t ) ( 6 ), the reaction with [KPb(OBu t ) 3 ] n shows a transfer of cyclopentadienyl ring from tin to lead to provide (C 5 H 5 )Pb(μ 2 -OBu t ) 2 Sn(OBu t ) ( 7 ). The new derivatives have been readily characterized by elemental analysis, multinuclear ( 1 H, 13 C, 119 Sn, and 207 Pb) NMR studies, molecular weight measurements, and volatility. A single-crystal X-ray diffraction study is reported for the compounds 1, 3, and 5 − 7 . The solid state structures of 1, 3, and 5 exhibit varying coordination behavior of M 2 (OPr i ) 9 - units to SnX + (X = C 5 H 5, Cl) fragments. In the structural framework of the tert -butoxide derivatives, the four membered MM‘(μ 2 -OBu t ) 2 ( 6, M = Ge, M‘ = Sn; 7, M = Pb, M‘ = Sn) ring is terminated at the metal ends by cyclopentadienyl and tert -butoxide ligands and each of the metals, bearing a stereochemically active lone pair, displays a pyramidal geometry.