Polyoxometalate-Catalyzed Insertion of Oxygen from O2 into Tin-Alkyl Bonds

The polyoxometalate H5PV2Mo10O40 mediates the insertion of an oxygen atom from H5PV2Mo10O40 into the tin-carbon bond of n-Bu4Sn through its activation by electron transfer to yield 1-butanol and (n-Bu3Sn)(2)O. The reaction is initiated by electron transfer from n-Bu4Sn to (H5PV2Mo10O40)-Mo-V to yield the ion pair n-Bu4Sn center dot+-(H5PVVMo10O40)-V-IV-Mo-V. The (H5PVVMo10O40)-V-IV-Mo-V moiety was identified by UV-vis and EPR. DFT calculations show that n-Bu4Sn center dot+-(H5PVVMo10O40)-V-IV-Mo-V is relatively unstable and forms more stable Bu+ and Bu3Sn+ cations coordinated to the polyoxometalate, which were also identified by ESI-MS. Products are released at higher temperatures. In the presence of molecular oxygen as the terminal oxidant the reaction is catalytic.