Table 1.

Characterization Data for 1–8.

	Opticala	Mössbauerb								X-ray
	λ, nm [ε, M−1cm−1]	δ(Fe1) [mm/s]	ΔEQ(Fe1) [mm/s]	Γ(Fe1) [mm/s]	Area(Fe1) [%]	δ(Fe2) [mm/s]	ΔEQ(Fe2) [mm/s]	Γ(Fe2) [mm/s]	Area(Fe2) [%]	Fe–Fe (Å)
1	290 (36,300) 410 (16,000)	1.18	2.33	0.38	53	0.97	2.25	0.35	47	3.61
2	290 (36,700) 418 (14,000)	1.10 1.23*	2.04 2.58*	0.38 0.57*	63 59*	0.95 1.15*	2.02 1.75*	0.32 0.49*	37 41*	3.61
3	290 (32,300) 375(11,100) 479 (3,300, sh) 600 (2,300)	0.49*	1.38*	0.56*	100*	—	—	—	—	3.01
4	284 (108,000) 372 (38,000) 570 (10,300)	0.52	0.95	0.38	100	—	—	—	—	3.49
5	370 (25,000) 540 (8,060)	0.51	1.06	0.40	100	—	—	—	—	3.06 3.78c
6/7	380 (sh) 473 600	0.47 0.46d 0.51*	1.52 1.59d 1.24*	0.36 0.58d 0.62*	21 85d 61*	0.50 0.48d 0.49*	0.97 1.03d 0.78*	0.48 0.34d 0.44*	79 15d 36*	3.44
8	360 (81,700) 550 (17,100)	0.49*	0.97*	0.44*	100*	—	—	—	—	—

^aAbsorption spectra were recorded in dichloromethane.

^bMössbauer spectra were acquired at 80 K; polycrystalline samples were prepared by mixing with Apiezon M grease and solution samples, which are marked with an asterisk

^*, were prepared in tetrahydrofuran.

^cThis value corresponds to the Fe–Fe distance between two diiron units.

^dThe polycrystalline sample of 6/7 was dried under vacuum at 150 °C for 24 h.