Table 4.

Experimental and predicted isomer shifts for all iron complexes included in the isomer shift fit.

Complex	Iron oxid. statea	Exp.b T (K)	Exp.b δ (mms−1)	T-corr.c δ (mms−1)	Predictedd
					Gas-ph. δ (mms−1)	COSMO δ (mms−1)
[Fe(SEt)4]1−	Fe3+	4.2	0.25	0.25	0.37	0.37
[FeS4C8O4]2−	Fe2+	4.2	0.668	0.668	0.60	0.62
[Fe(SPh)4]2−	Fe2+	4.2	0.66	0.66	0.60	0.60
[Fe(H2O)5(NO)]2+	{FeNO}7	80	0.76	0.79	0.87	0.85
[Fe(NO)(dtci-Pr2)2]e	{FeNO}7	4.2	0.35	0.35	0.34	0.33
[Fe(SPh)2(NO)2]1−	{Fe(NO)2}9	4.2	0.182	0.182	0.21	0.21
[Fe(SC2H3N3)(SC2H2N3)(NO)2]	{Fe(NO)2}9	296	0.188	0.31	0.27	0.28
[Fe2S2(S2-o-xyl)2]2−	2*Fe3+	4.2	0.28	0.28	0.36	0.35
[Fe2S2(OPh-p-CH3)4]2−	2*Fe3+	4.2	0.37	0.37	0.46	0.47
[Fe2S2(C4H4N)4]2−	2*Fe3+	77	0.26	0.29	0.33	0.32
[Fe2(NO)2(Et-HPTB)(O2CPh)]2+	2*{FeNO}7	4.2	0.67	0.67	0.65	0.67
[Fe(NO)2{Fe(NO)(N(CH2CH2S)3)}-S, S′]	{FeNO}7	77	0.18	0.21	0.19	0.19
	{Fe(NO)2}9	77	0.37	0.40	0.40	0.39
[Fe4S4(SPh)4]2−	4*Fe2.5+	4.2	0.46	0.46	0.43	0.40
[Fe4S4(OPh)4]2−	4*Fe2.5+	4.2	0.5	0.5	0.48	0.49
	2*Fe2.5+-SPh	4.2	0.48	0.48	0.47	0.48
[Fe4S4(SPh)2Cl2]2− f
	2*Fe2.5+-Cl	4.2	0.51	0.51	0.50	0.47
[Fe4S4(OPh)2Cl2]2− f	2*Fe2.5+-OPh	4.2	0.51	0.51	0.47	0.48
	2*Fe2.5+-Cl	4.2	0.52	0.52	0.48	0.50
[Fe4S4Cl4]2−	4*Fe2.5+	4.2	0.52	0.52	0.50	0.51
[Fe4S4(SCH2COOEt)4]2−	4*Fe2.5+	78	0.43	0.47	0.43	0.43
[Fe4(NO)4(μ3-S)4]	4*{FeNO}7	78	0.15	0.18	0.20	0.20
[Fe4(NO)4(μ3-S)4]−	2*{FeNO}7.5	RT g	0.156	0.27	0.21	0.30
	2*{FeNO}7	RTg	0.156	0.27	0.29	0.21
Mean absolute error	-	-	-	-	0.040	0.039

^aFeNO oxidation states are given in the Enemark-Feltham notation. The numbers preceding the * indicate the number of equivalent iron sites.

^bExperimental values (see Table 1 for references).

^cTemperature-corrected isomer shift (to 4.2 K) based on second-order Doppler shift.

^dPrediction based on the universal fit.

^eExperimental isomer shifts from Fe(NO)(dtcEt₂)₂.

^fExperimental values were assigned so that smaller isomer shift was assigned to higher nuclear density.

^gRT = room temperature, assumed to be 298 K.