Unusual Inorganic Biradicals: A Theoretical Analysis

The biradical character β (1 for an ideal biradical) is determined from multi-reference configuration interaction (MRCI) wavefunctions. Triatomics in the series FX2+ (X=O, S, Se, Te, Po) exhibit unusually high biradical characters for X=Te, Po (0.76<β<0.92), the largest among the homologous 18 valence electron molecules CX22−, NX2−, X3, and OX2. On the same scale, the biradical character of O3 is just 0.19, whereas that of C(CH2)3 is 0.97.