1H and (31)P NMR and EPR of Pentaammineruthenium(III) Complexes of Endocyclically Coordinated Nucleotides, Nucleosides, and Related Heterocyclic Bases. Autoxidation of [(Guokappa(N7))(NH(3))(5)Ru(III)] (Guo = Guanosine). Crystal Structure of [7MeGuakappa(N9)(NH(3))(5)Ru]Cl(3).3H(2)O.
The (1)H-NMR spectra of complexes involving the paramagnetic metal center [(NH(3))(5)Ru(III)] coordinated at ring nitrogens have been examined with pyridine, purine, nucleoside, and nucleotide ligands along with (31)P-NMR of the nucleotide complexes and EPR of representative complexes. Variations in the spectra have been investigated as a function of the coordination site and pH. Pseudocontact and contact shifts have been calculated for various protons, and an attempt has been made to correlate sugar conformations in coordinated 5'GMP, 5'IMP, Guo, and Ino with paramagnetically induced shifts. The compound [(7MeGuakappa(N9))(NH(3))(5)Ru]Cl(3).3H(2)O crystallizes in the orthorhombic space group Pna2(1) with cell parameters a = 25.375(4) Å, b = 11.803(4) Å, c = 6.958(2) Å, Z = 4, and R = 0.042. The autoxidation of [L(NH(3))(5)Ru(III)], where L = Guo, dGuo, and 1MeGuo, to the corresponding 8-oxo complexes under atmospheric oxygen is first order in the complex and [OH(-)]. For L = Guo, k = 6.6 x 10(-5) M(-1) s(-1), DeltaH = 58 kJ/mol, and DeltaS = -124 J/(mol K).
Rodriguez-Bailey
V. M.
VM
Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02167, and Department of Chemistry, Northwestern University, Evanston, Illinois 60208.
LaChance-Galang
K. J.
KJ
Doan
P. E.
PE
Clarke
M. J.
MJ