¹⁴N Nuclear Quadrupole Resonance of Some Heterocyclic Compounds

Abstract

The proton NMR transmitter part of the nuclear magnetic double resonance apparatus previously reported (Nippon Kagaku Kaishi, 1979, 961) was improved in order to make the apparatus more stable and versatile. With this improved spectrometer, the ¹⁴N nuclear quadrupole resonances of pyrimidine derivatives of biological and pharmacological interests have been observed at room temperature,
( a ) 1, 2, 4-Triazine-3, 5(2 H, 4 H)-dione [6-azauracil]
( b ) 6-Methyl-1, 2, 4-triazine-3, 5( 2 H, 4 H)-dione [6-azathymine]
( c ) 5-Fluoro-2, 4(1 H, 3 H)-pyrimidinedione [5-fluorouracil]
( d ) 5-Fluoro-1-(tetrahydro-2-fury1)-2, 4(1 H, 3 H)-pyrimidinedione
The ¹⁴N coupling constant e²Qq/h (in kHz) and asymmetry parameter η are [2510, 0.51] for ( a ) ; [2450, 0.56] for ( b ) ; [3040, 0.36], [2680, 0.51] for ( c ) ; and [2680, 0.57] for ( d ). For the latter two compounds, ( c ) and ( d ), the observed lines were assigned to particular nitrogen sites in these molecules and electronic distribution on a nitrogen atom was calculated with the Towes and Dailey theory.