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

Abstract

Diacetylplatinum(II) complexes [Pt(COMe) 2( ▪)] ( ▪ = bpy, 3a; 4,4′- t-Bu 2-bpy, 3b), obtained by the reaction of [Pt(COMe) 2X(H)( ▪)] with NaOH in CH 2Cl 2/H 2O, were found to undergo oxidative addition reactions with halogens (Br 2, I 2) yielding the platinum(IV) complexes ( trans, OC-6-13)/( cis, OC-6-32) [Pt(COMe) 2X 2( ▪)] ( ▪ = bpy, X = Br, 4a/4b; I, 4c/ 4d; ▪ = 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( ▪)] ( ▪ = 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 Me 3SiX/H 2O, yielding diacetyl(hydrido)platinum(IV) complexes [Pt(COMe) 2X(H)( ▪)] ( ▪ = bpy, X = Cl, 5a; Br, 5b; I, 5c; ▪ = 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( ▪)] ( ▪ = bpy, X = Br, 6b; I, 6c; ▪ = 4,4′- t-Bu 2-bpy, X = Br, 6e; I, 6f). All complexes were characterized by microanalysis, IR and 1H and 13C NMR spectroscopy. Additionally, the bis(thiocyanato) complex 4j was characterized by single-crystal X-ray diffraction analysis.