Ronald E. Schuster

Proton Magnetic Resonance Coordination Number Study of Al(III), Be(II), Ga(III), In(III), and Mg(II) in Water and Aqueous Solvent Mixtures

Cation coordination number measurements of AlCl3, AlBr3, Al(ClO4)3, Al(NO3)3, BeCl2, GaCl3, GA(ClO4), InCl3, In(Cl)4)3, and Mg(ClO4)2, in water, and in aqueous acetone mixtures have been carried out by a proton magnetic resonance method. At low temperatures, solutions of these electrolytes exhibit separate proton resonance signals for bulk water, and water molecules in the first solvation shell of the cation. Integration of these signals provides a direct measure of the coordination number of the cation. The Al(III) and Ga(III) are solvated by six water molecules in all solutions, regardless of the anion present. The Be(II) is coordinated by four water molecules in water and in aqueous acetone mixtures. The In(III) and Mg(II) could only be studied in aqueous acetone mixtures, wherein they are each coordinated by six water molecules. With the possible exception of Be(II) no evidence for contact ion pairing was found.

Proton Magnetic Resonance Coordination‐Number Study of AlCl3 in Aqueous Mixtures of Acetone, N,N‐Dimethylformamide, Dimethylsulfoxide, Dioxane, Tetrahydrofuran, and Tetramethylurea

The coordination number of Al(III) in aqueous mixtures of acetone, dimethylformamide, dimethylsulfoxide, dioxane, tetrahydrofuran, and tetramethylurea was measured over a range of solvent concentrations by a proton magnetic resonance technique. At low temperatures, proton exchange is slowed to such an extent in these mixtures that separate resonance signals are observed for bulk water and water molecules in the Al(III) solvation shell. Coordination numbers were measured by direct integration of the two water signals. The measurements show that in aqueous mixtures of acetone and tetramethylurea, and over a small solvent concentration range, dioxane and tetrahydrofuran, only water solvates Al(III). This was indicated by the value of six molecules obtained for the contribution of water to the Al(III) solvation shell in these mixtures. In aqueous mixtures of dimethylformamide and dimethylsulfoxide, wherein separate signals were also observed for the nonaqueous components, both solvents contribute to the Al(II...

A nuclear magnetic resonance rate study of N,N-dimethylformamide complexes with AlCl3, BeCl2, GaCl3, SbCl5 and TiCl4

A nuclear magnetic resonance rate study of complexes of N,N-dimethylformamide (DMF) with AlCl3, BeCl2, GaCl3, SbCl5 and TiCl4 has been carried out. Measurements were made possible by the observation of separate resonance signals for bulk and complexed DMF in all solutions. Rate constants at 290°k varied from 2 sec-1 for the AlCl3. (DMF) n system to about 150 for the BeCl2. (DMF) n solution. Activation energies for the exchange process were also measured for all solutions.

Proton Magnetic Resonance Solvation Study of Sc(NO3)3, Y(NO3)3, and Th(NO3)4 in Water–Acetone Mixtures

Cation coordination measurements of Sc(NO3)3, Y(NO3)3, and Th(NO3)4 in water–acetone mixtures have been made by a proton magnetic resonance method. At low temperatures, solutions of these salts exhibit separate proton resonance signals for bulk water and water molecules in the primary solvation shell of the cation. Integration of these signals provides a direct measure of the number of water molecules coordinated to the cation. Values of 3.9, 2.4, and 2.9 were obtained for Sc(III), Y(III), and Th(IV), respectively, over a range of salt and solvent concentrations. These values may reflect extensive ion pairing in these solutions, particularly in the Y(III) and Th(IV) cases. The PMR spectra of Th(IV) solutions revealed multiple signals for the protons of coordinated water molecules, lending evidence to the postulate of ion pairing in these systems.

A PROTON MAGNETIC RESONANCE STUDY OF BORON TRIHALIDE COMPLEXES WITH DIETHYL ETHER.

Abstract : At low temperatures, separate proton resonance signals are observed for bulk ether and ether molecules complexed with the boron halide. The methyl signal separations for the BF3, BCl3 and BBr3 complexes show a trend which is opposite to what one would predict on the basis of electronegativities of the halogen atoms. (Author)