Combining rival π‐space descriptions of O₃ and of SO₂

Abstract

Two rival solutions have emerged from applications of spincoupled (SC) theory, also known as the full-generalized valence bond (full-GVB) approach, to the p system of O 3 . The lowest solution (SC d ) corresponds to significant diradical character but there is a second solution (SC c ) which lies fairly close in energy. Combining these two descriptions, it turns out that both of them make significant contributions, with neither being dominant. The situation is entirely different for SO 2 , with the SC c description being overwhelmingly dominant over SC d . It can be concluded from an examination of various combinations of rival p-space descriptions for both molecules that neither of the SC c nor SC d solutions provides a very satisfactory description on its own of the p system in O 3 , but that SO 2 is already fairly well described by SC c before the explicit incorporation of any SC d character.

Computational Studies of Rubber Ozonation Explain the Effectiveness of 6PPD as an Antidegradant and the Mechanism of Its Quinone Formation

“…As a result, much of the highest quality theoretical literature on O 3 chemistry resorts to one of a number of MR schemes. 49,93 Nevertheless, many single-reference (SR) approaches to O 3 modeling have been reported. 50,62,94−103 Errors in these predictions can be substantial.…”

“…Ozone is a difficult modeling problem because the truth lies somewhere between these two extremes, and a number of researchers have quantified the degree of biradical character in O 3 , with values ranging from 16–49%. − Regardless of the exact value, it is clear that O 3 is a genuinely multireference (MR) system. As a result, much of the highest quality theoretical literature on O 3 chemistry resorts to one of a number of MR schemes. , …”

“…As a result, much of the highest quality theoretical literature on O 3 chemistry resorts to one of a number of MR schemes. 49 , 93 …”