Quantum chemical calculations have been performed on B3 ring stabilized Y-Y interaction (Y = Be, Mg, Ca) to understand the possibility of binuclear sandwich type complex formation. Calculations indicate single reference character of the studied systems. The complexes have been found to be stable towards dissociation into different fragments. Thermodynamic consideration also indicates the favourability of their formation. Increase in aromaticity of the parent B3 ring upon complexation is observed which is expected to provide extra stability to the complexes.

Attachment of one electron to 1,2-diBeX-benzene and 1,2-diZnX-benzene derivatives leads to the formation of stronger Be-Be and Zn-Zn interaction. This is reflected in the dramatic shortening of the Be-Be and Zn-Zn distance. The formation of these 2-center-1-electron bonds have also been confirmed by topological survey of electron density using quantum theory of atoms in molecules and electron localization function. The formation of these bonds is expected to render stability to these radical anions. These radical anions are stable towards electron detachment and computed bond dissociation energy values are also significant.

Quantum chemical calculations have been carried out to investigate the hydrogen storage capacity of Be2(NLi)2 cluster which contains ultra-short beryllium-beryllium distance. Calculations reveal that the cluster can take up to 6 H2 molecules reaching a maximum gravimetric density of 16.6 wt%. All the H2 binds at the Li atom with a moderate binding energy which is required for reversible storage of H2. Symmetry adapted perturbation analysis reveals significant contribution of electrostatic and induction and very minor contribution of dispersion towards the total interaction energy. The interaction between the H2 and Li centre is found to possess significant covalency. Molecular dynamics simulations reveal that the H2 molecules are strongly bound at 77K and get slowly released at elevated temperature.

Quantum chemical calculations were carried out to establish the half-sandwich structural behaviour between heavier group-14 elements (Si-Pb) and neutral Be3 ring. The proposed complexes are found to be global minima on the potential energy surface. Quantum chemical investigation revealed that the complexes found possess high bond dissociation energy and also favorable thermodynamics of their formation. The complexes were also found to possess significant aromatic behaviour. In addition, the half-sandwich complexes were found to possess promising chemical properties to be useful for potential H2 storage material under reversible conditions.

In silico search for planar hexacoordinate silicon center has been initiated by global minimum screening with density functional theory and energy refinement using coupled cluster theory. The search resulted in a local minimum of SiAl3Mg3H2+ structure which contains a planar hexacoordinate silicon center (phSi). The phSi structure is 5.8 kcal/mol higher in energy than the global minimum. However, kinetic studies reveal that the local minimum structure has enough stability to be detected experimentally. Born-Oppenheimer molecular dynamics (BOMD) simulations reveal that the phSi structure can be maintained up to 400 K. The formation of multiple bonds between the central silicon atom and framework aluminium atom is the key stabilizing factor for the planar structure.

Catalytic CO2 reduction mediated by Ru-PNP pincer complexes has been studied using density functional theory (DFT). Calculations clearly reveal that modification of the PNP pincer framework by introducing planar conjugation in the backbone improves the catalytic efficiency. Activation strain model reveals that reduction of strain in the transition states with modified PNP framework associated with the insertion of CO2 molecule is responsible for lowering the activation barrier. Calculations also reveal that electron withdrawing substituents at the PNP ligand improves the catalytic performance.

An extended computational approach has been utilized to explore the reactions of acids with carbonyl oxide, also known as Criegee intermediate (CI). The reactions were explored inside water cluster containing 50 water molecules. All possibilities of product formation were considered. Among the considered acids, the rate of 1,4-insertion follows the order - HCOO < HCl < HNO3. The most stable products of the reactions between the considered acids and CI have been identified.

An extended computational approach has been utilized to explore the reactions of acids with carbonyl oxide, also known as Criegee intermediate (CI). The reactions were explored inside water cluster containing 50 water molecules. All possibilities of product formation were considered. Among the considered acids, the rate of 1,4-insertion follows the order - HCOO < HCl < HNO3. The most stable products of the reactions between the considered acids and CI have been identified.