Coordination states of divalent transition-metal perchlorates in hexamethylphosphoramide solutions
Abstract
Molar conductances have been determined for Mn(ClO4)2, Co(ClO4)2, Ni(ClO4)2, Cu(ClO4)2 and Zn(ClO4)2 in hexamethylphosphoramide (HMPA) solutions at 25 °C. Visible absorption spectra of Co(ClO4)2, Ni(ClO4)2 and Cu(ClO4)2 in HMPA solutions indicate the existence of complex electrolytes of the type [M(HMPA)2+4· 2ClO–4]. The tetrahedral Co(HMPA)2+4 cation is the only detectable species in HMPA solutions of Co(ClO4)2, while the equilibria between tetrahedral and square-planar tetrakis-(HMPA) species have been shown to move toward the former species as the concentration of Ni(ClO4)2 or Cu(ClO4)2 is increased. Close agreement among the molar conductances indicates that the tetrahedral tetrakis-(HMPA) cations are present in HMPA solutions of Mn(ClO4)2 and Zn(ClO4)2. The limiting molar conductances of the solvo-cations and the first-step association constant are derived.
Please wait while we load your content...
