. Author manuscript; available in PMC: 2020 May 29.

Published in final edited form as: J Am Chem Soc. 2019 May 16;141(21):8557–8573. doi: 10.1021/jacs.9b02443

Table 2.

Select Zero-Field ⁵⁷Fe Mößbauer Parameters for (^RPI)Fe Complexes and Related Structures. ^a

[Fe]	δ (mm/s)	\|ΔE_Q\| (mm/s)	Ox. State	[Fe]	δ (mm/s)	\|ΔE_Q\| (mm/s)	Ox. State
(^iPrPI)Fe(COD) ^b	0.52	0.89	Fe(I), S_Fe = 3/2	(^iPrDI)Fe(η⁴-C₅H₈) ^f	0.56	1.68	Fe(I), S_Fe = 3/2
soln. ^c	0.52	0.89		(^iPrPI)₂Fe ^h	0.75	1.18	Fe(II), S_Fe = 2
BS(3,1) ^d	0.53	1.09		(^MePI)₂Fe ^e	0.75	1.18	Fe(II), S_Fe = 2
(^MePI)Fe(COD) ^e	0.49	0.92	Fe(I), S_Fe = 3/2	(^MesPI)₂Fe	0.74	1.33	Fe(II), S_Fe = 2
BS(3,1) ^d	0.52	1.05		(^iPrDI)₂Fe ⁱ	0.77	1.81	Fe(II), S_Fe = 2
(^iPrDI)Fe(COD) ^f	0.48	1.31	Fe(I), S_Fe = 3/2	(^iPrPDI)Fe(N₂)₂ ^j	0.39	0.53	Fe(0)–Fe(II) hybrid, S_Fe = 0
(^iPrPI)Fe(M^viM^vi) ^g	0.52	1.26	Fe(I), S_Fe = 3/2	(^iPrPDI)Fe(N₂) ^j	0.38	1.72	Fe(II), S_Fe = 1
BS(3,1) ^d	0.54	1.35		(^iPr(TB)PDI)Fe(N₂)₂ ^k	0.45	0.83	Fe(0)–Fe(II) hybrid, S_Fe = 0
(^MePI)Fe(M^viM^vi)	0.53	1.94	Fe(I), S_Fe = 3/2	(^iPr(TB)PDI)Fe	0.63	2.47	Fe(I), S_Fe = 3/2
				(CH₂CHCH₂)₂NTs ^k
BS(3,1) ^d	0.53	1.17		(^iPr(TB)PDI)Fe	0.73	1.87	Fe(I), S_Fe = 3/2
				(CH₂CHCH₂)₂ ^k

All measurements recorded at 80 K for solid powder samples unless noted otherwise. Complete ligand structures for all listed complexes depicted in the Supporting Information.

See Figure 1D.

Solution state sample frozen in C₆H₆.

Calculated using the optimized, broken symmetry structure computed at the B3LYP/def2-SVP/def2-TZVP level of density functional theory with the ZORA relativistic correction.

From a sample of 90% (^MePI)Fe(COD) and 10% (^MePI)₂Fe.

Taken from Ref. 26.

See Figure 1E.

See Figure 1F.

ⁱ

Taken from Ref. 38a

Taken from Ref. 42

Taken from Ref. 25.