DIRECT CHARACTERIZATION OF MIXED COMPLEXES OF GALLIUM(3) WITH N,N-DIMETHYLFORMAMIDE AND 2,4-PENTANEDIONE . PROTON MAGNETIC RESONANCE STUDY OF FIRST COORDINATION SPHERE STIOCHIOMETRY AND KINETICS OF LIGAND EXCHANGE

At temperatures below 40° the proton rtmr signals of N,N-dimethylformamide (DMF) in the first coordination sphere of Ga(III) can be distinguished. From relative intensities of these signals, a primary solvation number of 6 can be calculated for Ga(III). From the temperature dependence of the proton relaxation rates, the solvent (DMF) exchange parameters k1 (sec-1 at 25°), ΔH‡ (kcal/mol), and ΔS‡(eu) were calculated to be 1.7, 14.6, and -8.3, respectively. Proton nmr spectra of solutions of Ga(DMF)63+ and tris(2,4-pentanedionato)gallium(III) [Ga(acac)s] were used to characterize the complexes Ga(acac)(DMF)42+and Ga(acac)2(DMF)2+. Thermodynamic parameters were obtained from the temperature dependence of the equilibria among these species. Gallium-71 nmr spectra of Ga(DMF)63+ are reported. Data from this study are compared with those obtained for the analogous Al(III) and Be(II) complexes. © 1969, American Chemical Society. All rights reserved.