Synthesis, Characterization, and Stability of α‐Keggin‐Type Polyoxotungstate‐Coordinated Mono‐Platinum(II) Complex

The first example of mono-platinum(II) complex composed of mono-lacunary alpha-Keggin-type polyoxotungstate is described. The mono-platinum(II)-containing polyoxotungstate [(CH3)(4)N](4)H[alpha-PW11O39{cis-Pt-II(Me(2)ppz)}]center dot 5H(2)O (Me(2)ppz = N,N '-dimethylpiperazine) (TMA-1) was synthesized by a 1:1 stoichiometric reaction of mono-lacunary alpha-Keggin polyoxotungstate, [alpha-PW11O39](7-), with cis-PtCl2(Me(2)ppz) in an aqueous solution, followed by purification from water. The compound TMA-1 was characterized by elemental analysis, thermogravimetric/differential thermal analysis (TG/DTA), and Fourier transform infrared (FTIR), ultraviolet-visible (UV/Vis), and solution {H-1, C-13, P-31, Pt-195, and W-183} nuclear magnetic resonance (NMR) spectroscopy. The characterization results indicated that a platinum(II) moiety, [cis-Pt(Me(2)ppz)](2+), was coordinated to two oxygen atoms in a mono-vacant site of [PW11O39](7-) with asymmetric configuration, resulting in an overall C-1 symmetry. The polyoxoanion [alpha-PW11O39{cis-Pt-II(Me(2)ppz)}](5-) (1) was more stable in dimethylsulfoxide and water than the alpha-Keggin-type polyoxotungstate-coordinated mono-platinum(II) complex, [alpha-PW11O39{cis-Pt(NH3)(2)}](5-), which was also obtained by the reaction of [alpha-PW11O39](7-) with cis-diamminedichloroplatinum(II) in an aqueous solution.