Insights into the geometrical parameters, charge distribution, and reactivity of Ca, Mg, Sr, and Bi complexes of piroxicam and meloxicam: A quantum chemical study

DFT studies have been used to calculate the geometrical parameters of optimized structures, along with the charge distribution and reactivity of the respective compounds. The gas-phase optimization of the recently synthesized Ca, Mg, Sr, and Bi complexes of piroxicam and meloxicam were carried out using B3LYP functional in the Gaussian program and 6-31G(d,p), LanL2DZ, and SDD basis set in a sequel. The charge distribution around metal atoms was analyzed using the same basis set. The reactivity descriptors were calculated from the frontier molecular orbitals (FMOs) energy calculations. The relationship between geometrical parameters, the dipole moment of the complexes, and the type of metal were established in this study. The charge analysis study dictated the less electron-back donation with the increased size of the metal atom. The theoretical calculations concluded that the studied complexes are soft, more polarizable, and prefer to act as electrophiles during chemical reactions with nucleophiles.