Preparation and electrochemical behaviour of dinuclear platinum complexes containing NCN ligands (NCN = [C6H3(Me2NCH2)(2)-2,6](-)). The crystal structure of [C6H3(Me2NCH2)(2)-1,3-(C C)-5](2)

A series of homodinuclear Pt compounds containing the anionic, potentially terdentate NCN ligand (NCN= [C6H3(Me2NCH2)-2,6](-)) or its 4-ethynyl deriva tive were prepared. The two platinum centres are linked together in two dif ferent fashions: (i) directly linked by an ethynyl or diethynylphenyl group (head-to-head) and (ii) indirectly bonded by a ethynyl- or butadiynyl-link ed bis-NCN ligand (tail-to-tail). The reaction of the head-to-head sigma, s igma'-ethynylide complex {Pt}C=C(Pt) ({Pt} = [Pt(C6H3{CH2NMe2}(2)-2,6)](+)) with [CuCl](n) yields {Pt}Cl and [Cu2C2](n), while with [Cu(NCMe)(4)[BF4] a Cu(I) bridged complex was formed: [(eta (2)- {Pt} C dropC{Pt})(2)Cu] [BF4 ]. The results of cyclic voltammetry experiments reveal that both connectio n modes of the two platinum centres lead to electrochemically independent P t-NCN units. The X-ray crystal structure analysis of the neutral, tail-to-t ail bridging butadiyne bis-NCNH ligand [C6H3(CH2NMe2)-1,3-(C dropC)-5](2) i s reported. (C) 2001 Elsevier Science B.V. All rights reserved.