BOND-ENERGIES, IONIZATION-POTENTIALS, AND THE SINGLET-TRIPLET ENERGY SEPARATIONS OF SNCL2, SNBR2, SNI2, PBCL2, PBBR2, PBI2, AND THEIR POSITIVE-IONS

Spectroscopic properties, ionization potentials, dissociation energies, and the (1)A(1)-B-3(1) energy separations were determined for SnX(2) and PbX(2) (X=Cl,Br,I). The methods of calculations employed were complete active space self-consistent field (CASSCF) followed by multireference single + double configuration interaction (MRSDCI). The ground state for all these molecules corresponded to a (1)A(1) state, followed by a B-3(1) State as the first excited, and the B-1(1) state as the second excited state. The ground states of positive ions of these species were computed to be the (2)A(1) state. The B-2(1)-(2)A(1) energy separations of the positive ions were computed. The (1)A(1)-B-3(1) separations are: 60.0 kcal/mol for SnCl2, 55.5 kcal/mol for SnBr2, 47.1 kcal/mol for SnI2, 69.7 kcal/mol for PbCl2, 65.0 kcal/mol for PbBr2, and 53.8 kcal/mol for PbI2. The properties of the (1)A(1) ground state are R(e) = 2.363 (Angstrom), theta(e) = 98.4 degrees, mu(e)= 3.739 (D), I.P. = 9.72 (eV>, and D-e = 3.50 (eV) for SnCl2; R(e) = 2.535 (Angstrom) theta(e) = 99.7 degrees, mu(e)= 3.400 (D), I.P. = 9.34 (eV>, and D-e = 3.22 (eV) for SnBr2; R(e) 2;738 (Angstrom, theta(e) = 100.9 degrees, mu(e) = 2.863 (D), I.P.=8.62 (eV), and D-e = 2.52 (eV) for SnI2; R(e) = 2.542 (Angstrom), theta(e) = 100.8 degrees, mu(e) = 5.289 (D), I.P. = 10.02 (eV), and D-e = 3.19 (eV) for PbCl2; R(e) = 2.684 (Angstrom), theta(e) = 101.5 degrees, mu(e) = 5.038 (D), I.P. = 9.64 (eV), and D-e = 3,O6 (eV) for PbBr2; and R(e) = 2.878 (Angstrom), theta(e) = 103.6 degrees, mu(e) = 4.277 (D), I.P. = 8.82 (eV), and D-e = 2.51 (eV) for PbI2. The general trends for SnX(2) and PbX(2) (X = Cl,Br,I) are discussed.