Protonation and substitution reactions of [{WFe 3S 4Cl 3} 2(μ-L) 3] 3- (L = SEt or OMe): Quantifying how metal content and spectator ligands individually affect reactivity

TY - JOUR

T1 - Protonation and substitution reactions of [{WFe 3S 4Cl 3} 2(μ-L) 3] 3- (L = SEt or OMe)

T2 - Quantifying how metal content and spectator ligands individually affect reactivity

AU - Garrett, Brendan

AU - Henderson, Richard A.

PY - 2010

Y1 - 2010

N2 - Kinetic studies on the substitution reactions of the terminal chloro-ligands of [{WFe 3S 4Cl 3} 2(μ-L) 3] 3- (L = SEt or MeO) by PhS - in the presence of [NHEt 3] + or [pyrH] + allow determination of the proton affinities and rates of PhS - and proton binding to the clusters. The behaviours of both clusters are similar and follow the same general kinetic characteristics established in earlier work for other synthetic Fe-S-based clusters. Comparison of the results obtained with [{WFe 3S 4Cl 3} 2(μ- SEt) 3] 3- with those of the isostructural [{MoFe 3S 4Cl 3} 2(μ-SEt) 3] 3- shows that changing a Mo for W in the cuboidal cluster framework has a large effect on the rates of binding of PhS - or a proton. In contrast, comparison of the results of [{WFe 3S 4Cl 3} 2(μ-SEt) 3] 3- with those of [{WFe 3S 4Cl 3} 2(μ-OMe) 3] 3- shows that changing the bridging ligands has only a small effect on the rates of binding of PhS - or a proton. The reactivities of [{MFe 3S 4Cl 3} 2(μ-L) 3] 3- are inconsistent with the major influence of the metal or bridging ligands being electronic, and are more consistent with their modulating the ability of the cluster to undergo bond length reorganisation during binding of the nucleophile or proton.

AB - Kinetic studies on the substitution reactions of the terminal chloro-ligands of [{WFe 3S 4Cl 3} 2(μ-L) 3] 3- (L = SEt or MeO) by PhS - in the presence of [NHEt 3] + or [pyrH] + allow determination of the proton affinities and rates of PhS - and proton binding to the clusters. The behaviours of both clusters are similar and follow the same general kinetic characteristics established in earlier work for other synthetic Fe-S-based clusters. Comparison of the results obtained with [{WFe 3S 4Cl 3} 2(μ- SEt) 3] 3- with those of the isostructural [{MoFe 3S 4Cl 3} 2(μ-SEt) 3] 3- shows that changing a Mo for W in the cuboidal cluster framework has a large effect on the rates of binding of PhS - or a proton. In contrast, comparison of the results of [{WFe 3S 4Cl 3} 2(μ-SEt) 3] 3- with those of [{WFe 3S 4Cl 3} 2(μ-OMe) 3] 3- shows that changing the bridging ligands has only a small effect on the rates of binding of PhS - or a proton. The reactivities of [{MFe 3S 4Cl 3} 2(μ-L) 3] 3- are inconsistent with the major influence of the metal or bridging ligands being electronic, and are more consistent with their modulating the ability of the cluster to undergo bond length reorganisation during binding of the nucleophile or proton.

UR - http://www.scopus.com/inward/record.url?scp=77951906176&partnerID=8YFLogxK

U2 - 10.1039/b925835c

DO - 10.1039/b925835c

M3 - Article

C2 - 20386803

AN - SCOPUS:77951906176

SN - 1477-9226

VL - 39

SP - 4586

EP - 4592

JO - Dalton Transactions

JF - Dalton Transactions

IS - 19

ER -