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 α‐Keggin‐type polyoxotungstate is described. The mono‐platinum(II)‐containing polyoxotungstate [(CH 3 ) 4 N] 4 H[α‐PW 11 O 39 { cis ‐Pt II (Me 2 ppz)}] · 5H 2 O (Me 2 ppz = N , N′ ‐dimethylpiperazine) ( TMA‐1 ) was synthesized by a 1:1 stoichiometric reaction of mono‐lacunary α‐Keggin polyoxotungstate, [α‐PW 11 O 39 ] 7– , with cis ‐PtCl 2 (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 { 1 H, 13 C, 31 P, 195 Pt, and 183 W} 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 [PW 11 O 39 ] 7– with asymmetric configuration, resulting in an overall C 1 symmetry. The polyoxoanion [α‐PW 11 O 39 { cis ‐Pt II (Me 2 ppz)}] 5– ( 1 ) was more stable in dimethylsulfoxide and water than the α‐Keggin‐type polyoxotungstate‐coordinated mono‐platinum(II) complex, [α‐PW 11 O 39 { cis ‐Pt(NH 3 ) 2 }] 5– , which was also obtained by the reaction of [α‐PW 11 O 39 ] 7– with cis ‐diamminedichloroplatinum(II) in an aqueous solution.