Internal Rotation of Disilane and Related Moleculesa Density Functional Study.pdfVIP

2 Internal Rotation of Disilane and Related 0 0 Molecules: a Density Functional Study 1 2 l u J 3 Felipe Valencia a Aldo H. Romero a Miguel Kiwi a 2 a b ] Ricardo Ram´ırez Alejandro Toro-Labb´e i c s aFacultad de F´ısica, Universidad Cat´olica de Chile - l Casilla 306, Santiago, CHILE 6904411 r t b Facultad de Qu´ımica, Universidad Cat´olica de Chile m . Casilla 306, Santiago, CHILE 6904411 t a m - d n Abstract o c [ DFT calculations performed on Si H , Si F , Si Cl , and Si Br are reported. 2 6 2 6 2 6 2 6 The evolution of the energy, the chemical potential and the molecular hardness, as a 1 v function of torsion angle, is studied. Results at the DFT-B3LYP/6-311++G** level 4 show that the molecules always favor the stable staggered conformations, with low 5 but significant energy barriers that hinder internal rotation. The chemical potential 5 and hardness of Si H remains quite constant as the sylil groups rotate around the 7 2 6 0 Si-Si axis, whereas the other systems exhibit different degrees of rearrangement of 2 0 the electronic density as a function of the torsion angle. A qualitative analysis of the / frontier orbitals shows that the effect of torsional motion on electrophilic attack is t a negligible, whereas this internal rotation may generate different specific mechanisms m for nu