Heat of formation of tris(acetylacetonato)gallium and the gallium–oxygen bond energy

Abstract

The standard heat of formation of monoclinic tris(acetylacetonato)gallium has been determined at 25° by reaction calorimetry. ΔH_f° Ga(C₅H₇O₂)₃(c,α)= 354·4 ± 1·5 kcal./mole Enthalpy changes for the following gas-phase reactions at 25° have been derived. Ga³⁺(g)+ 3C₅H₇O₂^–(g)= Ga(C₅H₇O₂)₃(g)ΔH_f.i.=–1507 kcal./mole, Ga(g)+ 3C₅H₇O₂(g)= Ga(C₅H₇O₂)₃(g)ΔH_f.r.=–290 kcal./mole The heterolytic (E′) and homolytic (E″) bond energies are as follows: E′_Ga–O= 251 ± 5 kcal./mole and E″_Ga–O= 48 ± 1 kcal./mole.