α-methylation and α-fluorination electronic effects on the regioselectivity of carbonyl groups of uracil by H and triel bonds in the interaction of U, T and 5FU with HCl and TrH3 (Tr = B, Al)

摘要: Abstract Quantum chemical calculations at the ωB97XD/6–311++G(d,p) level of theory have been executed to investigate effect substituents via hydrogen-bonded and triel-bonded complexes between uracil (U), thymine (T) 5-fluorouracil (5FU) with HCl for former complexes, BH3 AlH3 latter complexes. These are supported by single-point energy MP2/6–311++G(d,p) CCSD/6-31 + G(d,p) levels theory, Natural Bond Orbital (NBO) Molecular Electrostatic Potentials (MEPs) analyses, global/local reactivity descriptors. The results reveal that strongly bounded than ones, Al-containing dimers stronger B-containing ones. In addition, as central triel atom grows in size, (B–O bond) accompanied weak B–H⋯O unconventional H-bonds. According local descriptors, B–O bond is hard-hard interaction indicates association primarily charge controlled, while Al–O soft-soft orbital controlled. both Hydrogen well α-methylation slightly overestimates binding strength U, α-fluorination exerts opposite role underestimating U. overall, on thus regioselectivity very small, suggesting a competition two carbonyl groups terms structures energies.