N-hydroxyisocyanuric, HONCO, is believed to be the primary dissociation product of 1,3,5-trihydroxy-1,3,5-triazin-2,4,6[1H,3H,5H]-trione, also referred to as trihydroxyisocyanuric acid, or THICA. THICA is stable and can be considered a cyclic trimer of HONCO. HONCO itself, on the other hand, has never been definitively observed in the laboratory. The dissociation of HONCO produces CO and either HON (hydroxynitrene) or its rearrangement product HNO (nitroxyl). We present the results of <i>ab initio</i> calculations on HONCO as well as CO, HON and HNO in their ground states, their lowest triplet states, and their first excited singlet states. Lowest singlet and triplet states are studied using coupled-cluster theory including singly and doubly excited configurations (CCSD), and also multireference configuration interaction (MRCI). The excited singlet states were studied using equation-of-motion CCSD (EOM-CCSD) as well as MRCI. Standard basis sets are used. Structural data and vibrational frequencies for all species in their various states are presented. The lowest triplet and first excited singlet states of HONCO each show evidence of three stable conformers. The dissociation mechanism is investigated through exploration of the potential surfaces of each state.

<i>Ab initio</i> study of the ground and excited states of N-hydroxyisocyanuric acid and its decomposition products

2019 Spring National Meeting

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Ab initio study of the ground and excited states of N-hydroxyisocyanuric acid and its decomposition products