Table 2.

Effects of H-bonds on the Fe(III)–X bonding²³

X	H-Bond system (Fig. 8)	Fe–X/Å	Covalency (%Xnp)	EB(Fe–X)/ kcal mol−1	EB(hbs)b/ kcal mol−1
O2−	A	1.81 (1.81)a	49
O2−	B	1.74	73	−102
O2−	C	1.80	46	−83	−25
S2−	A	2.23 (2.20)a	61
S2−	B	2.17	81	−62
S2−	C	2.21	60	−55	−12

^aFrom XRD measurements.

^bH-bond stabilization