Rhodium complexes containing bidentate imidazolyl ligands: synthesis and structure

The preparation and characterisation of square planar cationic rhodium(I) dicarbonyl complexes ([Rh((mim)(2)C=O)(CO)(2)]+BPh4-] (1), {[Rh((mim)(2)CH2)(CO)(2)]+BPh4-} (2) and {[Rh((mBnzim)(2)CH2)(CO)(2)]+BPh4-} (3) [mim = N-methylimidazol-2-yl, mBnzim = N-methylbenzimidazol-2-yl] is reported. The carbonyl ligands in 2 and 3 are readily exchanged for triphenylphosphine to form{[Rh((mim)(2)CH2)(PPh3)(2)]+BPh4-} (7) and {[Rh((mBnzim)(2)CH2)(PPh3)(2)]+BPh4-} (8). Complexes 2 and 3 were characterised by multinuclear NMR spectroscopy as well as by X-ray crystallography. Structural characterisation by X-ray analysis confirmed that complexes 2 and 3 are essentially square planar. (C) 1999 Elsevier Science S.A. All rights reserved.