Chemical Properties of Mononuclear and Dinuclear Phenylplatinum(II) Hydroxo Complexes with Cod Ligands. Transmetalation of Arylboronic Acids, Coupling of the Phenyl Ligands, and Carbonylation

The reaction of bpy with [{Pt(Ph)(cod)} 2 (μ-OH)](BF 4 ) ( 1-BF 4; cod = 1,5-cyclooctadiene) in acetone splits a Pt−O bond to yield a mixture of Pt(CH 2 COMe)(Ph)(cod) ( 2 ) and [Pt(Ph)(bpy)(cod)](BF 4 ) ( 3-BF 4 ), whereas a similar reaction in toluene produces 3-BF 4 and Pt(OH)(Ph)(cod) ( 4 ). The complex 4 was obtained in solution and was not isolated as analytically pure crystals because of its gradual disproportionation, giving PtPh 2 (cod) ( 5 ). The dinuclear complex 1-BF 4 reacts with ArB(OH) 2 (Ar = Ph, C 6 H 2 F 3 -2,4,6) to form 5 and Pt(C 6 H 2 F 3 -2,4,6)(Ph)(cod) ( 6 ), respectively, via aryl group transfer from boron to platinum. The accompanying formation of B(OH) 3 has been confirmed by 11 B{ 1 H} NMR spectroscopy. The reaction of BF 3 ·Et 2 O with 1-BF 4 followed by the addition of NH 4 Cl(aq) produces biphenyl and PtCl 2 (cod), which takes place possibly via a dinuclear intermediate. The cationic dinuclear complex 1-BF 4 reacts with CO (1 atm) to form benzophenone. Since the reactions of AgBF 4 with Pt(COPh)(I)(cod) ( 7 ) and CO with [Pt(Ph)(THF)(cod)](BF 4 ) also yield benzophenone, the above carbonylation of 1-BF 4 is considered to involve mononuclear intermediates.