INFRARED MATRIX-ISOLATION AND THEORETICAL-STUDIES ON GLUTARIMIDE

Infrared spectra of glutarimide isolated in low-temperature Ar and Nz matrixes are reported. The molecular structure, vibrational frequencie s, and infrared intensities of glutarimide are calculated with ab init io Hartree-Fock and second-order Moller-Plesset perturbation (MP2) met hods as well as with density functional theory (DFT) using the nonloca l gradient corrected functional (BP86). The best overall agreement bet ween the calculated and experimental spectra has been obtained at the MP2/D95V* level. Unequivocal assignment of the experimental infrared bands is performed on the basis of the potential energy distribution ( PED). A striking similarity is noted for frequencies of the correspond ing CO and NH vibrations in glutarimide and in uracil, thymine, and th eir methyl derivatives. Furthermore, the significant flattening of the glutarimide ring, predicted by calculations, indicates its structural resemblance to pyrimidine bases. It is suggested that some glutarimid e drugs are able to intercalate between nucleic base pairs in the DNA helix or they may act as antagonists of uracil and thymine in biologic al processes.