Hydride transfer from transition metal hydrides to dihapto acyl ligands

Abstract

The dihapto acyl ligand in Cp 2Zr[C(O)R]X, (R = Me, Ph; X = Me, Cl) is subject to hydrogen transfer from Cp 2MH 2 (M = Mo, W), Cp 2ReH and CpReH 4(PMe 2Ph). The initial products are bimetallic dimers of the type Cp 2XZrOCH(R)ML n. The fate of this bimetallic species is highly dependent upon the Group VIB metal when Cp 2MH 2 is the hydride source. For M = Mo, a second hydrogen migrates to the acyl carbon, yielding Cp 2Zr(OEt)Me and products derived from Cp 2Mo. For M = W, CO bond scission occurs with retention of the WC bond, to yield the carbene complexes Cp 2WC(C)R along with various oxyzirconium products. Filled d orbitals are not necessary on the hydride source; Cp 2NbH 3 also readily reduces the acyl in Cp 2Zr[C(O)Me]Me.