Rearrangement of {α-P2W15} to {PW6} moieties during the assembly of transition-metal-linked polyoxometalate clusters.

We report the formation of two polyoxotungstates of the general formula [M6(PW6O26)(α-P2W15O56)2(H2O)2](23-) (M = Co(II) or Mn(II)), which contain {PW6} fragments generated from the [P2W15O56](12-) precursor, which demonstrates for the first time the transformation of a Dawson lacunae into a Keggin lacunary building block. Solution analysis of the clusters has been conducted via electrospray ionisation mass spectrometry.