The slowest water exchange at a homoleptic mononuclear metal center: variable-temperature and variable-pressure 17O NMR study on (Ir(H2O)6)3+

The exchange of water molecule with iridium(III) on the homoleptic mononuclear metal center (Ir(H2O)6)3+ involves an associative interchange mechanism. A negative volume and near-zero entropy of activation confirm the occurrence of this mechanism. This is the slowest water exchange of similar nature giving a rate constant of 1.1x10(super -10) s(super -1). The deprotonated (Ir(H2O)5(OH))2+ is more reactive than (Ir(H2O)6)3+. Water exchange on this species takes place through an interchange mechanism.