Cyclopentadienyl/Alkoxo Ligand Exchange in Group 4 Metallocenes: A Convenient Route to Heterometallic Species

A simple and efficient strategy for the synthesis of nonorganometallic heterometallic clusters from cheap organometallic precursors is reported. This unique synthetic method involves elimination of the cyclopentadienyl ring from Cp2MCl2 (M = Ti, Zr, Hf) as CpH in the presence of M′L2 or M′L′2 (M′ = Ca, Sr, Mn; CH3OCH2CH2OH = LH or (CH3)2NCH2CH2OH = L′H) in an alcohol as a source of protons. In the reactions presented, a series of compounds, [Ca4Ti2(μ6-O)(μ3,η2-L)8(η-L)2Cl4] (1), [Sr4Hf2(μ6-O)(μ3,η2-L)8(η-L)2(η-LH)4Cl4] (2), [Ca4Zr2(μ6-O)(μ-Cl)4(μ,η2-L)8Cl2] (3), [Sr4Ti2(μ6-O)(μ3,η2-L)8(η-L)2(η-LH)2Cl4] (4), [Ca4Zr2Cp2(μ4-Cl)(μ-Cl)3(μ3,η2-L)4(μ,η2-L)4Cl2] (5), [CaTiCl2(μ,η2-L′)3(η-L′H)3][L′] (6), [Ca2Ti(μ,η2-L′)6Cl2] (7), [Mn4Ti4(μ-Cl)2(μ3,η2-L)2(μ,η2-L)10Cl6] (8), and [Mn10Zr10(μ4-O)10(μ3-O)4(μ3,η2-L)2(μ,η2-L)16(μ,η-L)4(η-L)2Cl8] (9), were obtained in good yield. All of the complexes were characterized by elemental analysis, IR and NMR spectroscopy, and single-crystal X-ray structural analysis. Complex 8 belongs to a group of magnetic clusters that consists of Mn4 subunits held together by two μ-Cl bridges. Compounds 6 and 7 underwent thermal decomposition, yielding an alternative source for some heterometallic oxides, which were analyzed by X-ray powder diffraction.