Mono-Heteroatom Effects on Singlet–Triplet Energy Gaps of Divalent Five-Membered Ring XC₃H₃C (X = CH, N, P, and As)

Abstract

Heteroatom effects were investigated on singlet–triplet energy gaps of divalent five-membered ring XC ₃ H ₃ C, 1 _X and 2 _X (X = CH, N, P, and As) at B3LYP/6-311++G∗∗ level. All triplet states of 1 _X and 2 _X are more stable than the related singlet state. Δ G _{s − t} between singlet and triplet states of 1 _X and 2 _X were changed in the order (in kcal/mol): 1 _As (14.43) > 1 _P (10.07) > 1 _CH (9.60) > 1 _N (8.50) and 2 _N (11.56) > 2 _CH (9.60) > 2 _P (3.07) > 2 _As (2.13).

Keywords:

• Carbene
• five-membered ring
• heteroatom
• singlet–triplet energy gap