FORMATION AND CLEAVAGE OF HYDROXO-BRIDGED DINUCLEAR IRIDIUM(III) AMINE AND 1,2-ETHANEDIAMINE COMPLEXES

The equilibration reaction between the mononuclear species cis-Ir(NH3) 4-(H2O)2(3+) (and its deprotonated forms) and the dinuclear species ci s,cis-(H2O)(NH3)4Ir(OH)Ir(NH3)4(OH2)5+ (and deprotonated forms) and (N H3)4Ir(OH)2Ir(NH3)4(4+) has been studied at 60-100-degrees-C in 1 M (N a,H)ClO4 with [H+] = 10(-7) - 1.0 M using spectrophotometry and IE-HPL C. The corresponding 1,2-ethanediamine complexes were also studied. Th e results are interpreted in terms of the equilibria between the monon uclear and dinuclear (mono- and dihydroxo-bridged) species, and in the case of the 1,2-ethanediamine system also including meso (DELTA,DELTA ) as well as racemic (DELTA, DELTA/DELTA,DELTA) dinuclear species. Dat a for the equilibria between the dinuclear species have been published previously, and in this study the thermodynamic (K3/K(a)3, K4, K5 and K6) and kinetic (k3/K(a)3, k4 and k5 and k-3, k-4 and k-5) parameters for the equilibria between mononuclear and dinuclear monohydroxo-brid ged species are given.