Si(IV) cationic superalkalis: [SiCl3(LR3)2]

First principle calculation reveals that recently synthesized phosphine and chloride ligand substituted pentacoordinate Si species i.e., [SiCl₃(PMe₃)₂]⁺ not only behaves like an alkali but also exhibits cationic superalkali characteristics after suitable ligands substitution. A series of hypercoordinated Si based superalkali complexes have been designed based on phosphine and N-heterocylcic carbene (NHC) ligand. The electron donating group substituted phosphine and NHC ligand based pentacoordinate Si systems exibits very low ionization energy within the range of 3.5 to 4.5 eV. Frontier molecular orbitals (FMOs) analysis gives the idea about the variation of the ionization energy with HOMO energy. The significant first and second order hyperpolarizability values of these systems corresponds to high non-linear optical (NLO) properties. AdNDP and AIM analysis gives a clear idea about the covalent bonding nature of Si-P and Si-Cl bond in these systems.