Table 1.

Comparison of structural and spectral parameters for complexes 1–4. Mössbauer spectral parameters were obtained on solid samples at 80 K unless otherwise noted.

Complex	Formal Ox. State	N–N dist. (Å)	Fe–N2 dist. (Å)	νN–N [ν15N–15N](cm−1)	δ (mm s−1)	|ΔEQ| (mm s−1)
1	FeIFeI	1.186(7)	1.745(3)	1810 [1745]a	0.62b	1.41c
2	Fe0FeI	1.186(6)	1.744(3)	1749 [1690]	0.63	1.75
					0.49	1.71
3	Fe0Fe0	1.190(8)	1.758(4)	1683 [1632]a	0.45	1.74
4	Fe0Fe0	1.215(6)	1.750(4), 1.755(5)	1625[1566]a	0.47	2.48

^aValues obtained from resonance Raman spectroscopy in refs 7a and 7b.

^bFrom Mössbauer spectra of solid 4.2 K from ref 12

^cFrom Mössbauer spectra of solid at 170 K from ref 12.