Structures, energetics, and infrared spectra of the Cl--(H2S)n and Br--(H2S)n anion clusters from ab initio calculations

Anion clusters formed between a chloride or bromide anion and H2S molecules have been investigated using ab initio methods. Cluster structures, binding energies, and vibrational properties were predicted at the MP2 level with basis sets of aug-cc-pvtz and aug-cc-pvdz quality. Vibrational self consistent field ( VSCF) calculations were employed to correct the predicted harmonic vibrational frequencies of the dimer complexes for anharmonicity. The major finding of this work is that the clusters all feature '' solvated anion '' structural motifs, with an anion bound to perturbed, yet intact, H2S ligands. The binding energies of the H2S ligands to the anion decrease with larger cluster size, and this is reflected in blue shifted vibrational stretching frequencies.