Standard enthalpies of formation of bis(pentane-2,4-dionato)copper(II) and tetrakis[bis(pentane-2,4-dionato)cobalt(II)] and an estimation of the metal–oxygen bond energies

Abstract

Standard enthalpies of formation of the title compounds have been determined by solution calorimetry at 298.15 K as –181.8 ± 0.5 and –826.6 ± 2.2 kcal mol^–1 respectively. Estimates of the gas-phase enthalpies of the monomeric forms of the complexes lead to average bond energies of 38 kcal for Cu–O and 48 kcal for Co–O. In the solid tetramer the terminal Co–O bonds are almost twice as strong as the bridging Co–O bonds.