Computational study of the equilibrium geometry and anharmonic vibrational spectra of PbX2**NO and PbX2**ON (X=F, Cl, Br, I) complexes

Andrzej T Kowal (1)

1 Chemistry

Equilibrium geometry parameters of the open shell PbX2**NO and PbX2**ON (X=F, Cl, Br, I) complexes have been computed by second-order Z-averaged perturbation theory (ZAPT2) with Stevens-Basch-Krauss-Jasien-Cundari (SBKJC) scalar-relativistic effective core potentials (RECP) and basis sets on all atoms. Equilibrium geometries of both PbX2**NO and PbX2**ON bonding isomers conform to Cs symmetry structure with end-on ligand coordination, and are characterized by Pb-N bond length within 266.6 - 271.7 pm range, Pb-O distance of 267.8 - 275.8 pm, Pb-N-O angle within 109.2 - 120.7 deg range, and Pb-O-N angle of 117.1 - 127.8 deg. Anharmonic vibrational spectra of the PbX2**NO and PbX2**ON complexes have been calculated by direct correlation-corrected vibrational self-consistent field (CC-VSCF) method enhanced with second-order perturbative correction using potential energy surfaces (PESs) determined at ZAPT2/SBKJC+(d) level in curvilinear (internal) coordinates. Fundamental of ν(Pb-N) stretching mode has been computed at 232.8 to 209.0 cm-1 within PbX2**NO series whereas ν(Pb-O) stretching mode fundamental evaluation in PbX2**ON series afforded wavenumbers within 183.2 - 150.7 cm-1 range. Blue shift of the ν(N=O) stretching mode wavenumber upon PbX2**NO complex formation, computed in anharmonic approximation, 15.8 - 14.6 cm-1, correctly reproduces the effect observed in the low-temperature Ar matrix spectra of PbX2**NO compounds. Influence of complex formation on the νs(Pb-X) and νas(Pb-X) fundamentals of PbX2 halides has also been discussed. Two-dimensional mapping of the Vi,jcoup(Qi , Qj) mode-mode coupling potential has been used to rationalize the origin of mode coupling related anharmonic corrections.

Mots clés: Physical Sciences

Andrzej T Kowal. Computational study of the equilibrium geometry and anharmonic vibrational spectra of PbX2**NO and PbX2**ON (X=F, Cl, Br, I) complexes. Molecular Physics, 2010, 108 (12), pp.1665-1675. ⟨10.1080/00268976.2010.489519⟩. ⟨hal-00606289⟩