ic051956j_si_002.cif (58.18 kB)
Substituent Effects on Nitrosyl Iron Corrole Complexes Fe(Ar3C)(NO)
dataset
posted on 2006-03-06, 00:00 authored by Crisjoe A. Joseph, Matthew S. Lee, Alexei V. Iretskii, Guang Wu, Peter C. FordA series of nitrosyl tris(5,10,15-aryl)corrolate complexes of iron(III) Fe(Ar3C)(NO) with different substituents on the
aryl groups have been prepared, and certain spectroscopic and reaction properties were compared. The cyclic
voltammetric analysis of the various Fe(Ar3C)(NO) complexes demonstrated that both the one-electron oxidation
and one-electron reduction potentials respond in systematic and nearly identical trends relative to the electron-donor properties of the substituents. A similar pattern was seen in the nitrosyl stretching frequency, νNO, which
modestly decreased with the stronger donor substituents. Flash photolysis of Fe(Ar3C)(NO) solutions in toluene
leads to NO dissociation followed by rapid [NO]-dependent decay of the transients formed (presumably Fe(Ar3C))
to regenerate the original spectra. As was seen in an earlier flash photolysis study of Fe(TNPC)(NO) (TNPC3- =
5,10,15-tris(4-nitro-phenyl)corrolate; Joseph, C.; Ford, P. C. J. Am. Chem. Soc. 2005, 127, 6737−6743), the second-order rate constants, kNO, are all much faster ((1−9) × 108 M-1 s-1 at 298 K) than those for analogous iron(III)
complexes of porphyrins. However, on a more microscopic level there is no obvious pattern in these rates with
respect to the donor properties of the aryl ring substituents. The high reactivity of the ferric triarylcorrolates with NO
data is interpreted in terms of the strongly electron-donating character of the Ar3C3- ligand and the quartet electronic
configuration of the Fe(Ar3C) intermediate.