Studies on stability and structural aspects of hydrazide-based hypercoordinate silicon(IV) complexes

Abstract

The concept of hypercoordination has been extensively used and debated in the literature specifically in case of silicon complexes from the last three decades which has neither been proved nor disproved. In fact, all these silicon complexes reported in the literature consist of various bonding features i.e. covalent (C–Si, N–Si or X–Si), dative (N→Si or O→Si) and/or ionic (X-{Si+}, X = halogen). The present work compares the structural features of selected hypercoordinate silicon(IV) complexes derived from the hydrazide ligands and describes the relative stability aspects of penta- and hexa-coordinate hydrazide-based silicon dichelates with respect to the charge on central silicon atoms. Some selected examples of penta- and hexa-coordinate silicon complexes without having Si-halogen covalent bond reported in the literature were selected for the comparison of structural properties through DFT calculations. The results indicate that the electrophilicity on silicon atom in penta-coordinate silicon complexes are significantly higher, thus, indicating their better reactivity compared to their hexa-coordinate analogues.