No abstract

No abstract

No abstract

The effect of various solvents on the proton chemical shifts of a number of acyclic p-diketones and p-ketoesters has been observed by nuclear magnetic resonance spectroscopy. These shifts are discussed in terms of the dissociation of intran~olecular and inter~nolecular hydrogen bonds on dilution. A con~plex of benzcne with the en01 tautolner of the p-dicarbonyl molecule is proposed. The effect of solvents on the position of the tauto~neric equilibrium is discussed.

Ligand superhyperfine interactions due to 35,37Cl and 19F have been observed in the ESR spectra of MoOCl52−, MoOF52− and CrOF52−. The presence of both isotropic and anisotropic ligand hyperfine splittings indicates considerable covalency in these complexes. The bonding coefficients, which have been calculated with resonable accuracy, reveal moderately strong in-plane π bonding involving the metal dxy orbital and the ligand py orbital. The spin–orbit interaction of the halide ligand is shown to be important in determining the g values. A configuration-interaction treatment has been used to account for the spin densities in the ligand px and s orbitals. The ESR spectra show that in solutions of KCrOF4 in aqueous hydrofluoric acid two species, CrOF4− and CrOF52−, are present.