Synthesis, characterization, and acid–base properties of (N–N)PtIV(CH3)2(OH)2 − x(OCH3)x (x = 0, 1) complexes

Abstract

(N–N)Pt^IV(CH₃)₂(OH)_2 − x(OCH₃)_x (x = 0, 1; N–N = bipy, 4,4′-(CH₃)₂bipy, 4,4′-^tBu₂bipy, ArNC(CH₃)–C(CH₃)NAr (Ar = 3,5-(CF₃)₂C₆H₃, 3,5-(CH₃)₂C₆H₃, 2,6-(CH₃)₂C₆H₃) complexes have been prepared by oxidation of the appropriate (N–N)Pt^II(CH₃)₂ complexes using H₂O₂/H₂O. In methanol, the hydroxo–methoxy complexes are formed (x = 1), whereas in acetone, the dihydroxo complexes are formed (x = 0). A single-crystal X-ray structure determination establishes the structure of (4,4′-(CH₃)₂bipy)Pt^IV(CH₃)₂(OH)₂ as a dihydroxo compound with octahedral geometry, with the hydroxo ligands occupying apical coordination sites. The acidities of the protonated bipy hydroxo complexes, (4,4′-R₂bipy)Pt^IV(CH₃)₂(OH)(OH₂)⁺ cations, were determined in methanol. The acidities closely matched that of Cl₂CHCOOH (pK_a = 6.38 in CH₃OH).