Conceptual density functional study on the formation of supermolecules by the chemical interaction of some ligands as electron pair donors and boron trifluoride as electron pair acceptor

摘要

A number of Lewis bases,viz.,HCN,HNC,H_3C-CN and H_3C-NC are allowed to chemically interact with BF_3,a Lewis acid,through the process of charge transfer and bond formation leading to the formation of F_3B-NCH,F_3B-CNH,F_3B-NC-CH_3 F_3B-CN-CH_3 supermolecules.The ligands chosen are structural isomers with different donating atomic sites of varying degrees of softness.The density functional descriptors like hardness and chemical potential or electronegativity are invoked to study the rationality of formation of such charge transfer complexes.The fundamental theoretical generalizations relied upon in the study are the maximum hardness principle and the electronegativity or chemical potential equalization principle.The present work also attempts to address the stability of the above supermolecules in terms of the recently suggested semiempirical algorithms involving the above stated density functional descriptors.The computed chemical potential induced charge transfer and hardness induced reaction energy of all such supermolecules are perfectly in accordance with their theoretical predictions.The computed values of the hardness,chemical potential and electronegativity of the donors,the acceptor and the supermolecules reveal that the formation of acid-base supermolecules are in accordance with the electronegativity equalization principle and the maximum hardness principle.The variation of heats of formation of the supermolecules with the change of structure of ligands can be correlated in terms of conceptual density functional descriptors like chemical potential and global hardness.The present work is presented as one more validity test of maximum hardness principle,MHP and chemical potential equalization principle of the density functional theory.