Structure of ScBr3 and Sc2Br6 molecules determined by the synchronous gas-phase electron diffraction and mass spectrometric experiment and quantum chemical calculations

Abstract

The structure of monomeric and dimeric molecules of scandium tribromide is studied by the synchronous electron diffraction and mass spectrometric experiment at T = 888(10) K and also by the quantum chemical calculations. The experimental data on the structural parameters of ScBr3 molecule were obtained for the first time; also for the first time the molecular structure of Sc2Br6 dimeric molecule was studied. It is found that the ScBr3 molecule has the C 3v effective configuration with the distance r g (Sc-Br) = 2.430(3) A and the valence angle ∠g(Br-Sc-Br) = 117.6(5)°. The equilibrium structure of the given molecule is planar with D 3h symmetry. According to a theoretical study by DFT and MP2 methods, Sc2Br6 molecule has the equilibrium structure of D 2h symmetry with four Sc-Br bridge bonds. It was confirmed by the results of the electron diffraction analysis.