Ab-initio molecular orbital studies on the structural isomers of C₃Si₂H₄

Abstract

The exploration of the potential energy surface of C₃Si₂H₄, which is derived from the well-known pentagonal pyramidal B₅H₉ structure by isolobal and isoelectronic replacements, shows that there are large numbers of minimum energy structures with the relative energies ranging from 0 to 102 kcal/mol. The global minimum is the unconventional C^2v bridged isomer. The PES is characterized by the isomers having (i) pyramidal geometry, (ii) conventional five membered ring systems, (iii) multiple rings shared across their edges and (iv) tetrahedrane structures with the ring strain released through bridging. The low energy isomers are found to be those with (i) divalent silicons, (ii) 3c-2e bonds and delocalization, (iv) sharing through Si-Si linkage between the rings and (v) two silicon atoms meta to each other in the ring.