Inorganic Chemistry, Vol.37, No.13, 3440-3443, 1998
Terminal ligand assignments based on trends in metal-ligand bond lengths of cubane-type [Fe4S4](2+,+) clusters
Trends in Fe-L bond distances in [Fe4S4L4](2-,3-) cubane-type clusters with L = Cl- and RS- are summarized. The compound (Et4N)(3)[Fe4S4(SH)(4)]. Et4NCl was prepared and structurally characterized. The Fe-SH bond lengths of this cluster and previously reported (Ph4P)(2)[Fe4S4(SH)(4)] fall in the ranges for clusters with alkyl- and arenethiolate terminal ligands. Upon slow crystallization from 1,2-dichloroethane/THF, the compound (Pr4N)(2)[Fe4S4(SH)(4)] undergoes chloride substitution to form (Pr4N)(2)[Fe4S4Cl4], which may be identified by its Fe-Cl distance. An X-ray structure recently attributed to (Pr4N)(2)[Fe4S4(SH)(4)] is that of (Pr4N)(2)[Fe4S4Cl4].
Keywords:IRON-SULFUR PROTEINS;ALTERNATIVE SPIN STATES;CRYSTAL-STRUCTURE;SYNTHETIC ANALOGS;REDUCED FERREDOXINS;ACTIVE-SITES;2+ CORE ;AQUEOUS-MEDIA;GROUND-STATES;SOLID-STATE