title: Unexpected explanation for the enigmatic acid-catalysed reactivity of [Fe4S4X4](2-) clusters.
abstract: Density functional calculations show that Fe-S clusters undergo unexpected large structural changes when protonated at S. Protonation of prototypical cubanoid [Fe4S4X4](2-) to [Fe4S3(SH)X4](-) (X = Cl, SR, OR) results in formation of doubly-bridging SH, severance of one Fe-S bond, and creation of a three-coordinate Fe. These findings explain previously enigmatic results concerning the reactivity of these clusters, including the rates of protonation, pKa data, and the kinetics of acid-catalysed ligand substitution.
authors.affiliation: School of Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, UK. richard.henderson@ncl.ac.uk.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Alwaaly
authors.forename: Ian
authors.initials: I
authors.lastname: Dance
authors.forename: Richard A
authors.initials: RA
authors.lastname: Henderson
mesh_terms: D002384:Catalysis; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000737:chemistry* / Q000378:metabolism; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D013455:Sulfur / Q000737:chemistry* / Q000378:metabolism
chemical_list: D013455:Sulfur; D007501:Iron; D003545:Cysteine