Valence bond and molecular orbital studies of three N2O isomers, and valence bond representations for some azide decompositions

The results of STO-6G valence bond calculations with Lewis-type valence bond structures are reported for the S=0 spin ground states of the linear NNO (CXv) and NON (DXh) isomers of N2O. It is calculated that the singlet diradical character of the NON isomer is substantially larger than for the NNO isomer. The results of B3LYP/6-31G(d) density functional calculations are also reported for the CXv and DXh ground states, the single-determinant approximations to the lowest-energy S=1 spin excited states of these two isomers, and for the triangular C2v isomer. The calculated bond lengths are in accord with qualitative valence bond considerations. Valence bond formulations of mechanisms for O(N3)2MN2O+2N2 and C6(CH2N3)6M3C2+3H2+6HCN+6N2 decompositions are presented. These formulations exploit the singlet diradical character present in the azide substituents. The results of further molecular orbital calculations for the O(N3)2 decomposition are also provided