Sourav Pal

Bio: Sourav Pal is an academic researcher from University of South Carolina. The author has contributed to research in topics: Hydrogen bond & Natural bond orbital. The author has an hindex of 1, co-authored 1 publications receiving 30 citations.

Lithium bonding interaction in H 2 CY⋯LiF (Y=O,S)complexes: A theoretical probe

Abstract: Ab initio calculations at 6-31++G(d,p) level have been done on H2CY⋯LiF (Y=O,S) complexes choosing ten possible orientations in each complex. The effect of correlation on complex binding energies has been studied via single point MP2 (full) calculations done on 6-31++G(d,p) geometry. Binding energies have been corrected for basis set superposition error. Frequency calculations confirm that H2CO⋯LiF and H2CS⋯LiF complexes have three and two stable forms, respectively. The most stable form in each complex has been found to have a strong lithium bonding interaction and a secondary hydrogen bonding interaction. NBO analysis has revealed that in this form oxygen donates nσ lone pair while sulfur donates its nπ lone pair. In yet another stable form of these complexes, mixed donation of π and nσ electrons have been observed.

Some measures for making halogen bonds stronger than hydrogen bonds in H2CS-HOX (X = F, Cl, and Br) complexes.

Abstract: The properties and applications of halogen bonds are dependent greatly on their strength. In this paper, we suggested some measures for enhancing the strength of the halogen bond relative to the hydrogen bond in the H2CS–HOX (X = F, Cl, and Br) system by means of quantum chemical calculations. It has been shown that with comparison to H2CO, the S electron donor in H2CS results in a smaller difference in strength for the Cl halogen bond and the corresponding hydrogen bond, and the Br halogen bond is even stronger than the hydrogen bond. The Li atom in LiHCS and methyl group in MeHCS cause an increase in the strength of halogen bonding and hydrogen bonding, but the former makes the halogen bond stronger and the latter makes the hydrogen bond stronger. In solvents, the halogen bond in the Br system is strong enough to compete with the hydrogen bond. The interaction nature and properties in these complexes have been analyzed with the natural bond orbital theory.

Prediction and characterization of the HMgH⋯LiX (X = H, OH, F, CCH, CN, and NC) complexes: a lithium–hydride lithium bond

Abstract: In the present paper, a new type of lithium bonding complex HMgH⋯LiX (X = H, OH, F, CCH, CN, and NC) has been predicted and characterized. Their geometries (C∞v) with all real harmonic vibrational frequencies were obtained using the second-order Moller–Plesset perturbation theory (MP2) with 6-311++G(d,p) basis set. For each HMgH⋯LiX complex, a lithium bond is formed between the negatively charged H atom of an HMgH molecule and the positively charged Li atom of an LiX molecule. Due to the formation of the complexes, the Mg–H and Li–H bonds are elongated. Interestingly, the Li–X harmonic vibrational stretching frequency is blueshifted in the HMgH⋯LiX (Y = CCH, CN, and NC) complexes and redshifted in the HMgH⋯LiX (X = H, OH, and F) complexes. The binding energy of this type of lithium bond ranges from 12.18 to 15.96 kcal mol−1, depending on the chemical environment of the lithium. The nature of lithium–hydride lithium bond has also been analyzed with natural bond orbital (NBO) and atoms in molecules (AIM).

π-systems as lithium/hydrogen bond acceptors: Some theoretical observations

Abstract: Ab initio calculations at the Hartree–Fock and correlated levels and density functional theory calculations have been performed with 6-31++G(d,p) and 6-311++G(d,p) basis sets on LiF and HF complexes of benzene, ethylene, and acetylene Complex binding energies have been corrected for basis set superposition error, and zero point energy corrections have been done on Hartree–Fock binding energies Computed results indicate that the complexes exist in different conformations and among them those with π-lithium and π-hydrogen bonds are the most stable π-lithium bonds are stronger than π-hydrogen bonds The computed binding energies and geometry of HF complexes correlate well with the available experimental results LiF complexes with these π systems are found to be weaker than Li+ complexes but they are stronger than Li atom complexes Natural bond orbital analysis traces the origin of the weak interactions that stabilize the complex Li, as found in earlier cases, prefers the most symmetric site for interac

Origin and Nature of Lithium and Hydrogen Bonds to Oxygen, Sulfur, and Selenium

Abstract: Lithium and hydrogen bonded complexes of LiF and HF with H2CO, H2CS, and H2CSe have been investigated using higher level ab initio calculations. Extensive searches of the potential energy surfaces for equilibrium structures have been done at the Hartree−Fock level, and post Hartree−Fock calculations at MP2, MP4 levels and DFT calculations with B3LYP functional have been performed on the stable forms. 6-311++G(d,p) and 6-31++G(d,p) basis sets on H, C, O, and S and 6-311++G(d,p) basis set on Se have been employed throughout. NBO analysis of the wave functions have been done to trace the origin of various interactions that stabilize the complexes. Harmonic frequencies computed at Hartree−Fock level show that, of the 10 proposed structures, LiF and HF complexes have three and one stable forms, respectively. Potential energy surface features, structure, and stability of LiF complexes are completely different from those of HF complexes. Though it is commonly observed that lithium and hydrogen bonding interactio...