Quantum chemical study of structure, vibrational spectra and thermodynamic properties of molecular and ionic clusters existing in vapours over strontium dichloride

The cluster ions SrCl3-, Sr2Cl3+, Sr3Cl5+, Sr4Cl7+ and Sr5Cl9+ that were detected earlier in vapour over strontium dichloride at high temperatures ranging from 1100 to 1500 K have been studied theoretically. The equilibrium geometrical properties, vibrational spectra and thermodynamic properties were investigated by using the DFT, MP2 and MP4 methods. From the alternative structures considered, it was observed that the ions SrCl3-, Sr2Cl3+, Sr3Cl5+ and Sr5Cl9+ correspond to D-3h symmetry and Sr4Cl7+ corresponds to C-2v configuration, no isomers were identified for all cluster ions from the considered alternative structures. The enthalpies of formation, Delta H-f(o)(0) of the cluster ions were determined (in kJ mol(-1)): -994 +/- 3 (SrCl3-), -410 +/- 12 (Sr2Cl3+), -1202 +/- 16 (Sr3Cl5+), -1962 +/- 27 and -2718 +/- 20. [GRAPHICS] .