Galin Petrov

Untersuchungen über die Tautomerie von Dialkylestern der 1-Cyano-2-oxo-alkanphosphonsäuren durch die Methode der σϱ-Analyse und die LCAO-MO-Methode

The applicability of the principle of linear free energies to the tautomerism of dialkyl esters of 1-cyano-2-oxo-alkanephosphonic acids is studied. Correlations between the tautomeric equilibrium constants andTafts inductive constants, as well asKabachniksσϕ constants of the substituents in RO-groups at the phosphorus atom and those at the carbonyl group in some series of compounds of this type are found. The dominating inductive influence of the R-substituents on the position of tautomeric equilibrium in these compounds is proved also by model quantum chemical investigation of the effects of conjugation in the corresponding tautomeric forms byHückels LCAO—MO-method.

Nickel(II) and palladium(II) complexes of diphenylphosphinoacetone and its enolate

Complexes of diphenylphosphinoacetone (HL = Ph2PCH2COMe), [NiCl2(HL)2]1, [PdCl2(HL)2]2 and its enolate [NiL2]3 and [PdL2]4, have been synthesized and characterized by 31P, 1H NMR and IR spectroscopy. Single-crystal X-ray diffraction studies of 1–3 reveal square-planar geometry at the central atom. There is a trans arrangement in 1 and 2 and a cis arrangement for 3. A 1H NMR spin-saturation transfer experiment indicates that the complex 2 exists as a cis–trans equilibrium mixture in CDCl3 solution. Complex 4 has a structure analogous to that of 3, as revealed by 1H NMR spectroscopy. Steric reasons for the geometrical preferences are discussed.