X-ray crystal structures of [NHR3]2[Fe4S4X4] (X = PhS, R = Et or n Bu; X = Cl, R =  n Bu): implications for sites of protonation in Fe–S clusters

Abstract

The X-ray crystal structures of [NHR 3 ] 2 [Fe 4 S 4 X 4 ] (X = PhS, R = Et or n Bu; X = Cl, R = n Bu), reported in this paper, show NH…X interactions between the cation and the cubanoid cluster. Comparison of the cluster dimensions in [NHR 3 ] 2 [Fe 4 S 4 X 4 ] with those reported earlier for [NR 0 4 ] 2 [Fe 4 S 4 X 4 ] (R 0 = Me, X = PhS; R 0 = Et, X = Cl) indicates that N-H…X interactions have a negligible effect on the dimensions of the cluster. The relevance of these structures to understanding where on [Fe 4 S 4 X 4 ] 2protonation labilises the cluster to substitution is discussed. Electronic supplementary material The online version of this article (

Structural insight into halide-coordinated [Fe4S4XnY4−n]2− clusters (X, Y = Cl, Br, I) by XRD and Mössbauer spectroscopy

“…98 dData not available for BTMA salts; values for other salts are not comparable.eDerived from the (Et 4 N) 2 [Fe 4 S 4 Cl 4 ] structure determined at 213 K. 36,42 fFrom ref. 49, at 150 K.gBzEt 3 N + salt at 150 K, from ref. 100.hFrom ref.…”

“…At the same time, the packing in the crystal and thus the size and shape of the counter cation can cause lowering of the cluster symmetry and for all three types even lower symmetry caused by crystal packing was reported (Table 1). 37–61 Importantly, with these changes in cluster symmetry, essential properties such as the redox potentials, spin states, magnetic properties, and ligand exchange kinetics vary markedly. 1,6,8,13,14,20–23,37–40,47,50,56,62–84…”

Redox-Active 1D Coordination Polymers of Iron–Sulfur Clusters

“…The Rietveld least-squares refinement of the structure solutions against the synchrotron data was carried out using the GSAS-I software, based on starting models obtained with FOX. Restraints for bond distances and bond angles were introduced in the refinements based on published Fe 4 S 4 cubane structures, as well as from geometry information gathered from the CCDC/MOGUL module of the Cambridge Structural Database (CSD) . Besides appraisal of the usual figures of merit for powder structures, the crystallographic arrangements were also analyzed graphically using the CCDC Mercury software to ensure that the obtained refined crystallographic structures were chemically plausible.…”