Phenylimido functionalization of α-[PW12O40]3-

A synthetic route of potentially wide scope is reported herein for the organoimido functionalization of polyoxotungstates. This report focuses on the reaction between the monovacant lacunary polyoxotungstate, alpha-((n-C4H9)(4)N)(4)H-3[PW11O39], and W(NC6H5)Cl-4 in anhydrous acetonitrile. Evidence from H-1, P-31, W-183, and H-1-W-183 HMQC NMR spectroscopy, as well as cyclic voltammetry, electronic absorption, and elemental analysis, is presented for the formation of alpha-[PW12O39(NC6H5)](3-) (2) of C-s symmetry, which is structurally related to T-d alpha-[PW12O40](3-) (3) by formal oxide substitution. The electronic structure of 2 is significantly perturbed from 3 with significant arylimido -> tungsten charge transfer, primarily localized to the W(NC6H5) fragment with secondary charge delocalization onto the remaining W and corner-shared bridging O atoms. This is consistent with the similar to 800 ppm downfield W-183 NMR shift for the phenylimido-tungsten, modest cathodic shifts in reversible redox potentials, electronic and IR spectra, and density functional theory calculations.