In Situ Assembly, De-Metalation and Induced Repair of a Copper-Polyoxovanadate Oxidation Catalyst

摘要

Polyoxometalates (POMs) offer a rich dynamic solution chemistry so that in principle, the assembly and repair of POM oxidation catalysts in situ, i. e. under catalytic conditions, is possible. Here, we report the oxidative activity of a molecular copper vanadium oxide cluster [(Me2NH2)Cu(MeCN)V_(12)O_(32)Cl]~(2-): the catalyst self-assembles by reaction of CuII and [(Me2NH2)2V_(12) O_(32)Cl]~(3-) in solution and selectively oxidizes secondary alcohols (here: 1-phenylethanol) to the corresponding ketones in near quantitative yield. The catalyst can be deactivated in solution by removal of the Cu~(II) site from the catalyst. Subsequent catalyst re-assembly is achieved by addition of Cu~(II) ions, leading to the recovery of the catalytic activity. The system might serve as molecular model to study repair mechanism in POM catalysts with relevance for “green” oxidation processes.