Probing the limits of steric constraints in the oligomerization of copper(I) complexes: structures of two sterically congested oligomers

Oligomeric copper(I) clusters are formed by the insertion reaction of coppe r(I) aryloxides into heterocumulenes. The effect of varying the steric dema nds of the heterocumulene and the aryloxy group on the nuclearity of the ol igomers formed has been probed. Reactions with copper(I)2-methoxyphenoxide and copper(I)2-methylphenoxide with PhNCS result in the formation of hexame ric complexes hexakis[N-phenylimino(aryloxy)methanethiolato copper(I)] 3 an d 4 respectively. Single crystal X-ray data confirmed the structure of 3. S imilar insertion reactions of CS2 with the copper(I) aryloxides formed by 2 ,6-di-tert-butyl-4-methylphenol and 2,6-dimethylphenol result in oligomeric copper(I) complexes 7 and 8 having the (aryloxy)thioxanthate ligand. Compl ex 7 was confirmed to be a tetramer from single crystal X-ray crystallograp hy. Reactions carried out with 2-mercaptopyrimidine, which has ligating pro perties similar to N-alkylimino(aryloxy)methanethiolate, result in the form ation of an insoluble polymeric complex 11. The fluorescence spectra of oli gomeric complexes are helpful in determining their nuclearity. Ir has been shown that a decrease in the steric requirements of either the heterocumule ne or aryloxy parts of the ligand can compensate for steric constraints aci d facilitate oligomerization. (C) 1999 Elsevier Science Ltd. All rights res erved.