Synthesis and molecular structure of a new family of iridium-(III) and rhodium(III) complexes: [(η 5-Me 5C 5)Ir(LL)X] + and [(η 5-Me 5C 5)Rh(LL)Cl] +; LL = 2,2′-bipyridine or 1,10-phenanthroline; X = Cl or H. Single crystal structures of [(η 5-Me 5C 5)Ir(bpy)Cl]Cl and [(η 5-Me 5C 5)Rh(phen)Cl]ClO 4

Abstract

The four-coordinate d 6 title complexes were synthesized in nearly quantitative yield by reaction of 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen) in the presence of [Ir(η 5-Me 5C 5)Cl 2] 2 or [Rh(η 5-Me 5C 5)Cl 2] 2. The hydride species were prepared in 80% yield by reduction of the chloro-complexes with sodium cyanoborohydride in ethanol/water. Both hydrido complexes of iridium show a characteristic singlet in the 1H NMR spectrum δ −11.45 ppm for 2 and δ −11.35 ppm for 4, and the corresponding metal-hydride stretchings appear at 2040 and 2090 cm −1. [(η 5-Me 5C 5)Ir(bpy)Cl]Cl crystallizes in the orthorhombic space group Pbca with unit cell parameters a 13.876(5), b 17.468(6), c 17.017(6) Å. Refinement of 2392 observed reflections led to a value of R = 3.7 and R w = 5.0%. [(η 5-Me 5C 5)Rh(bpy)Cl]ClO 4 crystallizes in the monoclinic space group P2 1/ n with unit cell parameters a 8.191(4), b 12.200(5), c 22.222(8) Å, and β 97.54(2)°. Refinement of 2223 observed reflections led to the final values of R = 3.9, and R w = 6.9%. Both complexes exhibit a characteristic three-legged “piano-stool” arrangement.