Precision X-ray study of mononuclear dinitrosyl iron complex [Fe(SC2H3N3)(SC2H2N3)(NO)2]•0.5H2O at low temperatures

X-ray analysis of mononuclear dinitrosyl iron complex [Fe(SC2H3N3)(SC2H2N3)(NO)(2)]center dot 0.5H(2)O (1) has been performed at 100 K (the crystallographic data are: a = 18.5006(3) A, b = 9.5207(1) A, c = 13.5719(2) A, beta = 99.8860(7), V = 2355.04(6) A(3), space group C2/c, Z= 8). From precision study of 1, distribution snaps of deformation electron density (DED) have been obtained. Both DED and topological parameters clearly indicate that Fe-S bonds in 1 are similar, though originally one of the molecules of ligand 1,2,3-triazole-3-thione coordinates the Fe atom in a thiol form (A), while the other in a thione form (B). These bonds can be described as interatomic interactions of a peak-peak type. The geometry and bond lengths ill 5-membered cycles for A and B forms are rather similar. Fe-NO bonds can be described as interactions of a peak-hole type. The thermal motion of NO groups (even at 100 K) is highly anisotropic (this being ail intrinsic feature of NO groups), thus suggesting mobility of the Fe-NO bond. (c) 2008 Published by Elsevier B.V.