Reactivity of diacetylplatinum(II) complexes: Oxidative addition of halogens and hydrogen halides

Diacetylplatinum(II) complexes [Pt(COMe)(2)(N(sic)N)] (N(sic)N = bpy, 3a; 4,4'-t-Bu-2-bpy, 3b), obtained by the reaction of [Pt(COMe)(2)X(H)(N(sic)N)] with NaOH in CH2Cl2/H2O, were found to undergo oxidative addition reactions with halogens (Br-2, I-2) yielding the platinum(IV) complexes (trans, OC-6-13)/(cis, OC-632) [Pt(COMe)(2)X-2(N(sic)N)] (N(sic)N = bpy, X = Br, 4a/4b; I, 4c/4d; N(sic)N = 4,4'-t-Bu-2-bpy, X = Br, 4e/4f; I, 4g/4h). The diastereoselectivity of the reactions proved to be strongly dependent on the solvent. The oxidative addition of (SCN)(2) resulted in the formation of (OC-6- 13)-[Pt(COMe)(2)(SCN)(2)(N(sic)N)] (N(sic)N = bpy, 4i; 4,4'-t-Bu-2-bpy, 4j). In a reaction the reverse of their formation, the diacetylplatinum(II) complexes 3 underwent oxidative addition with anhydrous HX (X = Cl, Br, I), prepared in situ from Me3SiX/H2O, yielding diacetyl(hydrido) platinum(IV) complexes [Pt(COMe)(2)X(H)(N(sic)N)] (N(sic)N = bpy, X = Cl, 5a; Br, 5b; I, 5c; N N = 4,4'-t-Bu-2-bpy, X = Cl, 5d; Br, 5e; I, 5f). Furthermore, diacetyldihaloplatinum complexes 4 were found to undergo reductive elimination reactions in boiling methanol yielding acetylplatinum(II) complexes [Pt(COMe) X(N(sic)N)] (N(sic)N = bpy, X = Br, 6b; I, 6c; N(sic)N = 4,4'-t-Bu-2-bpy, X = Br, 6e; I, 6f). All complexes were characterized by microanalysis, IR and H-1 and C-13 NMR spectroscopy. Additionally, the bis(thiocyanato) complex 4j was characterized by single-crystal X-ray diffraction analysis.