Thermochemistry of heteroatomic compounds 18. The enthalpies of vaporization, solvation, and formation of isomeric 2,5-dimethyl-1-phenyl-1-thioxophosphorinan-4-ones

The enthalpies of solvation of four geometric isomers of 2,5-dimethyl-1-phe nyl-1-thioxophosphorinan-4-one in chloroform, nitrobenzene, and methanol we re calculated using the enthalpies of vaporization of the isomers determine d by the modified Solomonov-Konovalov method from the enthalpies of solutio n of the compounds in CCl4 and p-xylene and molar refractions. The enthalpi es of formation (DeltaH(f)degrees) of the isomers in the condensed and gas phase were assessed in the framework of Benson's group additivity scheme by summing the Delta Hf degrees values for phosphacycloketone fragments obtai ned from molecular mechanics calculations with the contributions of the phe nyl group and S atom attached to the P atom.