Salah Ezzaher

Influence of a pendant amine in the second coordination sphere on proton transfer at a dissymmetrically disubstituted diiron system related to the [2Fe]H subsite of [FeFe]H2ase.

Studies of the protonation of [Fe2(CO)4(kappa2-PNP)(mu-pdt)] (1; PNP = (Ph2PCH2)2NCH3) by HBF4.Et2O showed that the nature of the reaction product depends on whether the reaction is conducted in acetone or in dichloromethane. In acetone, an N-protonated form, 2, is isolated. Tautomerization of 2 in CH2Cl2 gives rise to a mu-hydride species 3. Variable-temperature NMR experiments have been performed to clarify the processes involved.

Directing protonation in [FeFe] hydrogenase active site models by modifications in their second coordination sphere

Subtle changes in the second coordination sphere of [Cl(2)bdtFe(2)(CO)(4)(Ph(2)P-CH(2)-X-CH(2)-PPh(2))] (bdt = benzene-1,2-dithiolate, X = NCH(3), NCH(2)CF(3), CH(2)) that do not influence the electronic character of the Fe(2) center can however direct protonation to three different sites: the N in the bis-phosphane, the Fe-Fe bond or the bdt-S.

Pentacoordinate iron complexes as functional models of the distal iron in [FeFe] hydrogenases

Mononuclear pentacoordinate iron complexes with a free coordination site were prepared as mimics of the distal Fe (Fe(d)) in the active site of [FeFe] hydrogenases. The complexes catalyze the electrochemical reduction of protons at mild overpotential.