Structures and properties of 5-Fluorouracil…CO complex

The interaction between 5-Fluorouracil (5-FU) and carbon monoxide were studied by the theoretical calculations using density functional theory (DFT) at B3LYP/6-311 + + G^** level. Twelve possible isomers of 5-FU have been found and the study demonstrates that the most stable one of all is the diketo structure 5-FU0. Based on the isomers of 5-FU, Forty-four complexes have been obtained. The results reveal that both C and O of CO can combine with H8 and H12 of 5-FU by forming a hydrogen bond between two molecules, C of CO has a privilege to bind with 5-FU, so this type of complexes are more stable. In addition, the stability of complex may relate to the stability of the isomers of 5-FU and the second order perturbation stabilization energies between C of CO and the single bond of 5-FU neighboring the hydrogen bond and 5-FU0-A is the most stable complex. (authors)