Bowl-shaped and highly inert bis(mu-hydroxo)-platinum(II) dimer

Steric effects are responsible for the bending in [(Pt(Me(2)phen)(mu -OH)}( 2)](2+) (Me(2)phen = 2,9-dimethyl-1,10-phenanthroline). The large hinge ang le is not expected on the basis of electronic effects alone, since hydroxo bridges and terminal nitrogen donors should lead to planar structures. Unex pected is the markedly increased stability against bridge-cleavage reaction s, which could be relevant for the mechanism of reactions catalyzed by Pt-I I and Pd-II complexes in aqueous medium. A structural study on the bridge-c leavage product [Pt-(Me(2)phen)(thiourea)(2)](2+) reveals strong distortion s.