Table 2. Calculated energy (kcal mol^–1) of closed-shell (CS), open-shell (OS), and triplet (T) ground-state and diradical character (y) of 4 and 5.

Method	Compound	CS	OS	T	y
B3LYP/def2-TZVPP	4	0.0	0.0	+29.1	0.00
	5	0.0	0.0	+10.7	0.43
BH&HLYP/def2-TZVPP	4	0.0	0.0	+27.8	0.0
	5	0.0	–2.3	+4.8	0.35