Inorganic Chemistry, Vol.48, No.19, 9308-9315, 2009
Structures and Reactivity Patterns of Group 9 Metallocorroles
Group 9 metallocorroles 1-M(PPh3) and 1-M(py)(2) [M = Co(III), Rh(III), Ir(III); 1 denotes the trianion of 5,10,15-tris-pentafluorophenylcorrole] have been fully characterized by structural, spectroscopic, and electrochemical methods. Crystal structure analyses reveal that average metal-N(pyrrole) bond lengths of the bis-pyridine metal(III) complexes increase from Co (1.886 angstrom) to Rh (1.957 angstrom)/Ir (1.963 angstrom); and the average metal-N(pyridine) bond lengths also increase from Co (1.995 angstrom) to Rh (2.065 angstrom)/Ir (2.059 angstrom). Ligand affinities for 1-M(PPh3) axial coordination sites increase dramatically in the order 1-Co(PPh3) < 1-Rh(PPH3) < 1-Ir(PPh3). There is a surprising invariance in the M(+/0) reduction potentials within the five- and six-coordinate corrole series, and even between them; the average M(+/0) potential of 1-M(PPh3) is 0.78 V vs Ag/AgCl in CH2Cl2 solution, whereas that of 1-M(Py)(2) is 0.70 V under the same conditions. Electronic structures of one-electron-oxidized 1-M(Py)(2) complexes have been assigned by analysis of electron paramagnetic resonance spectroscopic measurements: oxidation is corrole-centered for 1-Co(Py)(2) (g = 2.008) and 1-Rh(py)(2) (g = 2.003), and metal-centered for 1-Ir(tma)(2) (g(zz) = 2.489, g(yy) = 2.010, g(xx) = 1.884, g(av) = 2.128) and 1-Ir(py)(2) (g(zz) = 2.401, g(yy) = 2.000, g(xx) = 1.937, g(av) = 2.113).