B4CO2: a new, observable sigma-pi diradical.
A new sigma-pi diradical, B4(CO)2, prepared in matrix isolation, was characterized unambiguously by isotopic-substitution infrared spectroscopy and by theoretical computations. Both open-shell singlet and triplet states have three pi electrons but are aromatic with moderately large NICS values. Quantum chemical calculations at various levels indicate that the open-shell singlet is slightly more stable than the triplet state. However, the singlet and triplet are computed to have very similar IR features which do not allow experimental differentiation.
Zhou
Mingfei
M
Department of Chemistry, Fudan University, Shanghai 200433, P.R. China. mfzhou@fudan.edu.cn
Xu
Qiang
Q
Wang
Zhi-Xiang
ZX
Schleyer
Paul von Ragué
Pv