46626-B3
Studies on Heterobimetallics Containing Phosphinoethyl-, Aminoethyl-, and Diphenylphosphino-functionalized Cyclopentadienyl Group VI Metal Carbonyl Fragments
Heterobimetallic complexes with metal-metal bonds supported by bridging donor-functionalized cyclopentadienyl ligands facilitate reactions at metal-metal bonds that would likely afford homolytic or heterolytic M-M’ bond cleavage without the kinetic stabilization afforded by the bridging ligand. Recently reported reactions of neutral allylpalladium(II) complexes with free radicals resulting in reductive elimination of alkenes prompted us to synthesize heterobimetallics with (allyl)M fragments (M = Ni, Pd) bridged by (2-(diphenylphosphino)ethyl)cyclopentadienyl (CpPPh) group VI metal tricarbonyl metalloligands. The (2-methylallyl)nickel complexes M’{Ni(η3-C4H7)}(CO)3(μ-η5:η1-CpPPh) (M’ = Cr (1), Mo (2), W (3)), (cyclohexenyl)nickel complexes M’{Ni(η3-C6H9)}(CO)3(μ-η5:η1-CpPPh) (M’ = Cr (4), Mo (5), W (6)), and analogous (allyl)palladium complexes M’{Pd(η3-C3H5)}(CO)3(μ-η5:η1-CpPPh) (M’ = Cr (7), Mo (8), W (9)) were synthesized by salt elimination reactions. The formulations of 1-9 as heterobimetallics containing group VI-group X bonds supported by bridging CpPPh ligands were established in the solid-state by single crystal X-ray crystallography. Aaron Heerboth ’08 and the PI carried out this research during spring and summer 2008, respectively. This synthetic work sets the stage for on-going reactivity studies of 1-9 to target transformations at the coordinated allyl ligands.
