Synthetic, spectral and structural aspects of some Rh(III) pentamethylcyclopentadiene complexes containing N,N′-donor bridging ligands

Reactions of the chloro-bridged dimeric rhodium complex [{(η5-C5Me5)Rh(μ-Cl)Cl}2] with the N,N′-donor bridging ligands pyridine-2-carbaldehyde azine (paa), p-phenylene-bis(picoline)aldamine (pbp) or p-biphenylene-bis(picoline)aldamine (bbp) in 1:1 molar ratio in methanol led in the formation of cationic binuclear complexes [(η5-C5Me5)ClRh(μ-L)RhCl(η5-C5Me5)]2+ (L=paa, pbp or bbp) in high yield. It was further observed that reactions of the chloro-bridged dimeric rhodium complex [{(η5-C5Me5)Rh(μ-Cl)Cl}2], with an excess of the above mentioned ligands also, resulted in binuclear complexes. The reaction products have been characterized by microanalyses and spectroscopic studies (IR, 1H-, 13C-NMR, ESMS/FAB mass and electronic spectra). Molecular structure of the representative binuclear complex [(η5-C5Me5)ClRh(μ-paa)RhCl(η5-C5Me5)](BF4)2 has been confirmed by single crystal X-ray analysis. Crystal data: monoclinic, P21/n, a=10.2050(7), b=15.4470(7), c=24.959(2) Å, β=97.904(6)°, V=3897.1(5) Å3, Z=4, R=0.0609.