Water and protic acids as oxidants for platinum(II): Diorgano(hydrido)platinum(IV) and diorgano(hydroxo)platinum(IV) chemistry, including structural studies of poly(pyrazol-1-yl)borate complexes Pt(OH)R-2{(pz)(3)BH} (R=methyl, p-tolyl) and Pt(OH)Me-2{(pz)(4)B}center dot H2O

The tris(pyrazol-1-yl)borate complexes K[PtR2{(pz)(3)BH}] (R = Me (1), p-tolyl (2)) may be isolated on addition of K[(pz)(3)BH] to solutions of [PtR2(SEt2)](2). Complexes 1, 2, and [PtMe2{(pz)(4)B}](-) react with acetic acid to form PtHR2{(pz)(3)BH} (R = Me (3), p-tolyl (5)) and PtHMe2{(pz)(4)B} (4). The hydridoplatinum(IV) complexes decompose at similar to 140 (3) and similar to 85 (4)degrees C in toluene-d(8) and similar to 90 degrees C (5) in nitrobenzene-d(5) to form methane (3, 4) and toluene (5), where isolation of 5 has provided the first opportunity to study the decomposition of aryl(hydrido)platinum(IV) complexes. The hydridoplatinum(IV) complexes are deprotonated on addition of aqueous sodium hydroxide in acetone-d(6) to form 1, 2, and [PtMe2{(pz)(4)B}](-). The hydroxoplatinum(IV) complexes Pt(OH)R-2{(pz)(3)BH} (R = Me (6), p-tolyl (8)) or Pt(OH)Me-2{(pz)(4)B}. H2O (7) may be readily isolated in 45-82% yield upon oxidation of the platinum(II) anions 1, 2, or [PtMe2{(pz)(4)B}](-) by water. The hydridoplatinum(IV) complexes 3-5 also react slowly with water in acetone-d(6) to form hydrogen and complexes 6-8, The anions [PtR2{(pz)(3)BH}](-) undergo oxidative-addition reactions with iodomethane to form PtMeR2{(pz)(3)BH} (R = Me, p-tolyl). The octahedral hydroxoplatinum(IV) complexes 6-8 are the first examples of platinum(IV) complexes formed on oxidation by water to be characterized by X-ray crystallography. The complexes display Pt-O distances of 1.974(8)-1.996(6) Angstrom, and the Pt-N bond distances reflect the relative trans influences of the hydroxo and methyl groups. The aqua group in Pt(OH)Me-2{(pz)(4)B}. H2O (7) is hydrogen-bonded to the hydroxoplatinum(IV) group to form a centrosymmetric dimer, such that it is not possible to ascertain whether the coordination environment of platinum is [Pt(OH)... H2O](2) or [Pt(OH2)(+)... OH-](2), although the former is believed to be more likely.