C-13 AND O-17 NMR-STUDIES OF THE SOLUTION AND EQUILIBRIUM BEHAVIOR OF SELECTED OXOCYANORHENATE(V) COMPLEXES

Carbon-13 and oxygen-17 NMR spectroscopies were utilized to study the solution and protonation equilibrium behavior of the trans-dioxotetracyanorhenate(V) ion. The pK(a1) and pK(a2) values for the successive dissociation of the [ReO(H2O)(CN)4]- complex were determined from C-13 and O-17 NMR chemical shifts as 1.31 (7) and 3.72 (5), respectively. The dimeric species [Re2O3(CN)8]4-(formed by condensation of [ReO(OH)(CN)4]2- ions) and the monosubstituted product [ReO(NCS)(CN)4]2- were also studied, and results were correlated with NMR measurements in DMSO solutions. The "O chemical shifts for the different species studied showed a direct relationship with X-rav crystal structure and infrared data and with the electron density on the coordinated oxygen ligands and demonstrated the effectiveness of O-17 NMR spectroscopy for characterization of these types of complexes.