Metal-metal interactions in bent cyano-bridged trinuclear octacyanomolybdate(IV)-platinum(IV) complexes

The trinuclear cyano-bridged [(CN)(7)Mo-IV-CN-Pt-IV(L)(4)-NC-Mo-IV(CN)(7)]( 4-) species [L = NH3 (1), 1/2en (2)] have been synthesized by the inner-sph ere redox reaction of [Mo(CN)(8)](3-) with Pt(II) in aqueous solution. The complexes have been characterized in aqueous solution and in the solid stat e as localized-to-delocalized mixed-valence species with weak-to-moderate c oupling between Pt and Mo centers. The remote Mo centers in electrochemical ly generated [(CN)(7)Mo-V-CN-Pt-IV(L)(4)-NC-Mo-IV(CN)(7)](3-) are strongly coupled through trans-CN-Pt(L)(4)-NC- linkage. The ground state delocalizat ion Mo(IV)<----> Pt(IV) in the solid state results in valence-trapped Mo(IV )/Mo(V) sites on the IR and ESR timescale. The structure of Cs-2[Pt(en)(2)C l-2][(CN)(7)Mo-CN-Pt(en)(2)-NC-Mo(CN)(7)]. 10H(2)O is characterized by sign ificant bending of CN-bridges in the Pt(1)-N-C array. The network exhibits the large Cs+ cations trapped within the 'cage' formed by Cl, N and O atoms of [Pt(en)(2)Cl-2](2+), terminal CN ligands and water molecules, indicatin g a crucial role of Cs+ in stabilization of the structure. (C) 2001 Elsevie r Science B.V. All rights reserved.