A Series of Octahedral First-Row Transition-Metal Ion Complexes Templated by Wells-Dawson Polyoxometalates: Synthesis, Crystal Structure, Spectroscopic, and Thermal Characterizations, and Electrochemical Properties.

Three Wells-Dawson polyoxotungstates-based hybrid compounds of general formula [M(CHNO)][{M(CHNO)}(μ-PWO)]· nCHNO· n'HO [with M = Mn (1), Fe (2), Co (3) ; n = 2, 2, 3 and n' = 0, 0, 1, respectively] were synthesized at room temperature by a facile method and characterized by IR and H and P NMR spectroscopy studies, thermogravimetric analysis-differential scanning calorimetry thermal analyses, UV-vis, X-ray diffraction (XRD) powder and single-crystal XRD analyses, and cyclic voltammetry studies. From the X-ray study, it was established that the metal (M = Mn, Fe, Co) is located on an inversion center, being octahedrally coordinated to six dimethylformamide (DMF) molecules to form the complex cation [M(dmf)]. Also, in the dinuclear complex anion [{M(dmf)}(μ-PWO)], the M atoms are coordinated to five DMF molecules through the oxygen atoms, while the sixth coordination site is occupied by a terminal oxygen atom of the Wells-Dawson anion [PWO] that plays the role of a bridging ligand.

Effect of electron (de)localization and pairing in the electrochemistry of polyoxometalates: study of Wells-Dawson molybdotungstophosphate derivatives.

Polyoxometalates (POMs) are inorganic entities featuring extensive and sometimes unusual redox properties. In this work, several experimental techniques as well as density functional theory (DFT) calculations have been applied to identify and assess the relevance of factors influencing the redox potentials of POMs. First, the position of the Mo substituent atom in the Wells-Dawson structure, α1- or α2-P2W17Mo, determines the potential of the first 1e(-) reduction wave.