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Preparation, Crystal Structure, and Unusually Facile Redox Chemistry of a Macrocyclic Nitrosylrhodium Complex

TitlePreparation, Crystal Structure, and Unusually Facile Redox Chemistry of a Macrocyclic Nitrosylrhodium Complex
Publication TypeJournal Article
Year of Publication2010
AuthorsKristian KE, Song WJ, Ellern A, Guzei IA, Bakac A
Journal TitleInorganic Chemistry
Volume49
Pages7182-7187
Date Published08/02
ISBN Number0020-1669
Accession NumberISI:000280365300060
Keywords', -terpyridine, /6, 2, coordination, electron-transfer, ligand, METAL-COMPLEXES, nitric-oxide, no, photochemistry, reactivity, superoxorhodium(iii) complex, trpy=2
Abstract

The reaction between NO and L-2(H2O)Rh2+ (L-2 = meso-Me-6-1,4,8,11-tetraazacyclotetradecane) generates a sky-blue L-2(H2O)RhNO2+, a {RhNO}(8) complex. The crystal structure of the perchlorate salt features a bent Rh-N-O moiety (122.1(11)degrees), short axial Rh-NO bond (1.998(12) angstrom) and a strongly elongated Rh-OH2 (2.366(6)angstrom) trans to NO. Acidic aqueous solutions of L-2(H2O)RhNO2+ are stable for weeks, and are inert toward oxygen. The complex is oxidized rapidly and reversibly with Ru(bpy)(3)(3+), k(f) = (1.9 +/- 0.1) x 10(5) M-1 s(-1), to an intermediate believed to be L-2(H2O)RhNO3+. This unprecedented {RhNO}(7) species has a lifetime of about 90 s at room temperature at pH 0. The reverse reaction between L-2(H2O)RhNO3+ and Ru(bpy)(3)(2+) has k(r) = (1.5 +/- 0.4) x 10(6) M-1 s(-1). The kinetic data define the equilibrium constant for the L-2(H2O)RhNO2+/Ru(bpy)(3)(3+) reaction, K = k(f)/k(f) = 0.13, and yield a reduction potential for the L-2(H2O)RhNO3f/2+ couple of 1.31 V. Both the redox thermodynamics of L-2(H2O)RhNO3+/2+ and the kinetics of the reactions with Ru(bpy)(3)(3+2+) are quite similar to those of uncoordinated NO+/NO.
URL<Go to ISI>://000280365300060
DOIDoi 10.1021/Ic101236x