The vapor phase in equilibrium with cuprous chloride has been studied using the Knudsen effusion-mass spectrometric technique. The polymeric species Cu3Cl3, Cu4Cl4, and Cu5Cl5 were observed, the first two in comparable amounts. Partial pressures and heats of vaporization for each species were measured: 3 CuCl(s)→Cu3Cl3(g),   Δ H640o=33.7± 0.8 kcal/mole, 4 CuCl(s)→Cu4Cl4(g),   Δ H650o=34.6± 0.7 kcal/mole, 5 CuCl(s)→Cu5Cl5(g),   Δ H665o=41± 1 kcal/mole. The atomization energies for these molecules calculated on the basis of the Rittner ionic model are compared with the experimental values.

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SUMMARYThe energy surface of the urea molecule was studied at the Møller-Plesset, B-LYP and B3-LYP density functional levels. The scanning of the energy surface indicates the presence of two energy minima corresponding to nonplanar C2 and Cs symmetry structures. The C2 symmetry structure is the most stable one, while the Cs symmetry isomer lies 6 kJ mol −1 above the lowest energy minimum. The infrared spectra of the C2 symmetry stable isomer were computed at the MP2/DZ(d,p), B-LYP/DZ(d,p), B-LYP/6-311+G(d,p) and B3-LYP/6-311++G(2d,p) levels and the assignment of the harmonic vibrational frequencies was accomplished through the calculated potential energy distribution of urea and urea-d4.

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