Synthesis, characterization and structural studies of new heterometallic alkynyl complexes of platinum and Group II metals with chelating bis(diphenylphosphino)ferrocene ligand

摘要

Reaction of the platinum bis(alkynyl) complex [Pt(dppf)(C-CPh)(2)] (1) (dppf = bis(diphenylphosphino)ferrocene) with an equimolar amount of Group I I metal salts [Cu(NCMe)(4)]BF4 and AgBF4 initially gives 1: 1 mixed-metal complexes [Pt(dppf)(C CPh)(2)Cu(NCMe)]BF4 (2) and [Pt(dppt)(Cequivalent toCPh)(2)Ag]BF4 (3) in good yields. Upon standing in solution at room temperature, compounds 2 and 3 rearrange and aggregateto the corresponding diplatinum complexes [{Pt(dppf)(Cequivalent toCPh)(2)}(2)M]BF4(M = Cu(4), Ag (5)) which exhibit an intense molecular ion envelope for the respective cation in their electrospray mass spectra. Compounds 4 and 5 can also be formed when the reaction is performed using a 2:1 molar ratio of 1 and the Group I I salts. The X-ray crystal structures of 1, 4 and 5 have been determined. Structures of 4 and 5 reveal that the two square-planar platinum coordination planes in the cation are approximately orthogonal an 2-fashion to four carbon-carbon triple bonds to afford heterometallic pentanuclear Fe2Pt2M complexes (M = Cu, Ag) in which each platinum center is stabilized by a dppf ligand. Each of the new complexes displays a reversible oxidation couple corresponding to the ferrocenyl unit of dppf and there is less stabilization of the silver in the mixed-metal complex than in the copper congeners. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 43]