Vibrational analysis of nucleic acids. I. The phosphodiester group in dimethyl phosphate model compounds: (CH3O)2PO2-, (CD3O)2PO2-, and (13CH3O)2PO2-

摘要: Normal coordinate analyses and vibrational assignments are presented for the dimethyl phosphate anion [(CH3O)2PO2-] its deuteriomethyl [(CD3O)2PO2-] carbon-13 [(13CH3O)2PO2-] derivatives in gauche-gauche conformation. The anion, which is simplest model nucleic acid phosphodiester moiety, exhibits many of spectral complexities DNA RNA has previously resisted a complete consistent analysis. In present study we make use new experimental data on isotopomers, including Raman depolarization measurements, to develop valence force field normal modes C--O--P--O--C network hydrogenic substituents, as well stretching bending O--P--O anionic phosphodioxy group (PO2-). established incorporates one significant nonbonded constant, introduced from ab initio calculations, account interaction between two ester C--O bonds. This resolves previous problematic conformation-sensitive symmetric (in-phase) asymmetric (out-of-phase) skeletal linkages demonstrates substantial anharmonicity hydrogen-stretching vibrations methyl substituents. New proposed bands group, may serve potential indicators structure phosphates.