Abstract: This paper is the first one about research of the relations between properties and electronic structure for cyclourea nitro-amine compounds by CNDO/2 method, It is found that the stretch vibration frequency (v_(CO)) of carbonyl in their molecules are linearly related with the Mulliken bond order (M_(CO)) of bond C=O and the two-atom energy (E_(CO)) between the C and O atoms, i.e., there are following linear relations:
v_(CO)=-5208+7394M_(CO) r=0.95 (1)
v_(CO)=-6057-4842E_(CO) r=-0.95 (2)
where r is correlation coefficient. Therefore, the position of the characteristic absorptive peak of the carbonyl of the some compounds in this series can be predicted by theoritical calculations and using equation (1) or (2). For example, for 2,4,6,8-tetranitro-semiglycoluril, the predicted ν_(co) values (1813 and 1826 cm~(-1)) are in good agreement with the experimental value (1825 cm~(-1)). According to theoretical analysis and based on results of CNDO/2 computations, it is shown that there exist the approximate linear relationship between the Mulliken bond order (M_(AB)) (from “population analysis”) and the two-atom energy (E_(AB)) (from “energy seperation”) for same type of bond (A—B) in cycloureide nitramine compounds, and it is also shown that M_(AB) is rigorously directly proportional to the resonace integral energy (E~r_(AB)), which is a term included in E_(AB). These indexes obtained by CNDO/2 calculations agree with each other for the measure of the bond strength and the stretch vibration frequency of the carbonyl. Else, the relation between the previous results and the classical review point of the theoritical organic chemistry are also discussed in this paper.