SYNTHESIS AND CHARACTERIZATION OF 1,4-DIIMINE COMPLEXES OF 1,2,3,4,5-PENTAMETHYLCYCLOPENTADIENYLRHODIUM AND IRIDIUM

Monomeric rhodium and iridium diimine complexes M(HNRNH)(Cp=1,2,3,4,5 -pentamethylcyclopentadienyl : (M =Ir; R=o-C6H4 (1a), 4,5-(CH3)(2)-C6H 2-1,2 (1b), 4,5-(Cl)(2)-C6H2-1,2 (1c), NCC=CCN-1,2 (1d) : M=Rh; R=NCC= CCN-1,2 (1e)) have been synthesized from [CpMCl(2)](2) and 2 equiv. o f diamine in the presence of NEt(3). The crystal structure of Ir was d etermined by X-ray diffraction method:la was crystallized in the monoc linic system, space group P2(1/c), with lattice constants a=9.543 (1) Angstrom, b=16.286 (1) Angstrom, c=10.068 (1) Angstrom and beta=99.25 (1), with Z=4. Least-squares refinement of the structure led to R fact or of 0.049. The coordination sphere of rhodium and iridium can be des cribed as a 2-legged piano-stool. All complexes are highly colored. El ectrochemical studies show that 1d and 1e display quasi-reversible red uction and 1a-1c display irreversible reductions, suggesting that the acceptor orbital might be localized on the diimine ring.