Bis(1, 2-ethylenedithiolato or 1, 2-benzenedithiolato)nickel complexes show unusual and useful physical and chemical properties originating from the unique electronic structure of the highly delocalized planar NiS4C4R4 system.1 The neutral complexes and their dianions, (NiS4C4R4)2-, undergo interesting reactions, mainly at the sulfur atoms.2, 3 Schrauzer et al. have prepared various S, S'-dialkyl and S, S'-diaralkyl derivatives4-6 and showed that the latter undergo photolysis with C-S bond cleavage more rapidly aerobically than anaerobically, consistent with a homolytic process, ultimately affording the neutral nickel complexes and termination products derived from aralkyl radicals. The aim of the present study was to elucidate the mechanisum of photodissociation of bis(S-benzyl-1, 2-diphenyl-1, 2-ethylenedithiolato)-nickel (1)4, 6, 7 by means of EPR and UV-vis absorption spectrometry. We were interested primarily in the following questions: (1) Are intermediate radicals observed, and can they be assigned, (2) Does the dissociation of both C-S bonds in 1 occur in one step or in a stepwise fashion, with intermediate formation of the radical species (formula omitted) (2), (3) Which of the excited states (singlet or triplet) is responsible for the reaction? The possible existence of 2 was previously suggested by Schrauzer and Rabinowitz.4.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry