Table 1.

Selected Bond Distances (Å) and Angles (deg) for Complexes 1 – 4

	1	2	3	4
Bond Distances
Fe1–S1	2.4352(4)	2.4343(4)	2.3573(4)	2.3753(6)
Fe1–N1	2.225(6)	2.220(5)	2.2818(13)	2.243(2)
Fe1–N2	2.274(6)	2.256(5)	2.1642(12)	2.1920(18)
Fe1–N3	2.263(5)	2.249(5)	2.1651(12)	2.1662(19)
Fe1–N4	2.2344(13)	2.2393(12)	2.2555(13)	2.2656(19)
Fe1–O1	2.1497(11)	2.2190(10)	–––	–––
Bond Angles
S1–Fe1–N1	101.60(16)	100.1(3)	100.82(3)	100.33(5)
S1–Fe1–N2	179.59(18)	179.0(2)	136.97(3)	138.78(5)
S1–Fe1–N3	101.43(15)	100.1(2)	138.07(3)	137.49(5)
S1–Fe1–N4	79.29(4)	79.28(3)	81.30(3)	80.61(5)
S1–Fe1–O1	95.91(3)	95.24(3)	–––––	–––––
N4–Fe1–N1	178.45(17)	179.3(3)	175.10(5)	176.81(8)
N4–Fe1–N2	100.34(17)	101.4(2)	100.88(5)	100.67(7)
N4–Fe1–N3	99.11(17)	101.0(2)	92.93(5)	94.70(7)
N4–Fe1–O1	89.59(5)	88.27(4)	–––	–––
N1–Fe1–O1	91.58(17)	91.5(2)	–––	–––
N2–Fe1–O1	84.26(17)	84.1(2)	–––	–––
N3–Fe1–O1	161.75(16)	163.3(3)	–––	–––
N1–Fe1–N2	78.8(2)	79.2(3)	80.64(5)	80.66(7)
N1–Fe1–N3	79.5(2)	79.3(3)	82.53(5)	82.54(8)
N2–Fe1–N3	78.4(2)	80.5(3)	84.95(5)	83.71(7)
Calculated Values
λocta	1.028	1.027	–––	–––
τ5b	–––	–––	0.62	0.63

^aOctahedral quadratic elongation, ${\text{λ}}_{\text{oct}}=\sum {\left(1_{\text{i}}/1_0\right)}^2/6$. l₀ represents the center to vertex distance of an octahedron with O_h symmetry whose volume is equal to that of the distorted octahedron with distances l_i. λ_oct = 1 for an ideal octahedron.³³

^b5-coordinate geometry index, τ₅ = (β – α)/60. β is the largest bond angle observed, and α is the second largest bond angle.³⁴