Cyclic and linear analogues of N2O. Theoretical evaluation of bonding properties

Various ABC (A, B=N, P; C=O, S) structures with 16 valence electrons in a linear and cyclic geometry, together with the corresponding transition states for interconversion, are evaluated by means of quantum chemical calculations at an ab initio double-ζ level and with inclusion of electron correlation treatment. The stability of cyclic structures comes to the fore with increasing substitution of the ABC systems by third row elements. Hence in contrast to N2O its higher element congener P2S is more stable in a cyclic structure rather than a linear arrangement of atoms. In the linear ABC systems where either A or B is constituted from the third row of the periodic table of elements, the heavier element is always terminal rather than central. This effect and the preference for cyclic rather than linear structures is the consequence of orbital nonhybridization as outlined in a previous publication. (orig.)