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)2-2,6]−) or its 4-ethynyl derivative were prepared. The two platinum centres are linked together in two different fashions: (i) directly linked by an ethynyl or diethynylphenyl group (head-to-head) and (ii) indirectly bonded by a ethynyl- or butadiynyl-linked bis-NCN ligand (tail-to-tail). The reaction of the head-to-head σ,σ′-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: [(η2-{Pt}CC{Pt})2Cu][BF4]. The results of cyclic voltammetry experiments reveal that both connection modes of the two platinum centres lead to electrochemically independent Pt–NCN units. The X-ray crystal structure analysis of the neutral, tail-to-tail bridging butadiyne bis-NCNH ligand [C6H3(CH2NMe2)-1,3-(CC)-5]2 is reported.