Platinum complexes with N-N-C ligands. Syntheses, electrochemical and spectroscopic characterisations of platinum(II) and relevant electroreduced species

A series of cyclometallated platinum(II) species with N-N-C ligands (N-N-C = ortho-C-deprotonated form of 6-benzyl-substituted 2,2'-bipyridines) and d ifferent fourth monodentate ligands (Cl-, I-, CN-, CO, PPh3, Py, MeCN) has been investigated electrochemically, with particular emphasis to the analys is of the relatively st;able one-electron reduced species. EPR spectra have been recorded at different temperatures on the electroreduced solutions. T he :analyses were supported by a systematic comparison with simulated spect ra and allowed a definition of the interaction of the additional unpaired e lectron with the Pt-195, N-14, and H-1 nuclei present in the molecule. Atte ntion has been also paid to the effects of the ligands on the thermodynamic s (E-1/2,E-r) of the reduction, as well as to some reactivity aspects of th e substrates that could be shown by voltammetric tests. A number of these c ompounds have been synthesised for the first time, so that a full character isation has been performed. (C) 2000 Elsevier Science S.A. All rights reser ved.