The molecular structure of 1,1-dichlorosilacyclopentane as obtained from gas-phase electron diffraction and ab initio calculations

NBO scheme including second-order perturbation analysis has shown that the major orbital stabilizing interactions are between the chlorine lone pair (nπ)Cl and the low-lying σSi-C2∗ and σSi-C5∗ antibonding orbitals. It was found that remote σSi-C → σC-H∗ interactions are stabilized by 4.4 kcal mol−1 and contribute to the stabilization of the C2 conformer in DCSCP. Deletion analysis was performed using various deletion algorithms like NOSTAR, NOVIC, NOGEM (see text). The stabilization energy for the C2 conformer resulting from the difference of the non-Lewis energy E(NL)C2 - E(NL)Cs was 7.1 kcal mol−1. Similar analyses using the same quantum mechanical procedures mentioned above have been conducted to study silacyclopentane (SCP), 1,1-difluorosilacyclopentane (DFSCP), and 1,1-dibromosilacyclopentane (DBSCP).