Synthesis and crystal structures of novel di- and mononuclear iron complexes chelating by PNP ligands related to [FeFe]-hydrogenases

As the biomimetic models of [FeFe]-hydrogenase active sites, two new di- and mononuclear iron complexes with chelating PNP ligands (PNP = (Ph2P)(2)NR) have been prepared and structurally determined by single-crystal X-ray diffraction analysis. Treatment of precursor Fe-2(mu-edt)(CO)(6) (A, edt = SCH2CH2S) with diphosphine (Ph2P)(2)N(CHMe2) in the presence of Me3NO center dot 2H(2)O in MeCN produced a dinuclear iron complex Fe(mu-edt)(CO)(4){kappa(2) -(Ph2P)(2)N(CHMe2)} (1), whereas the similar reaction of Fe-2(mu-odt)(CO)(6) (B, odt = SCH2OCH2S) with (Ph2P)(2)N(CH2)(3)Me afforded a mononuclear iron complex Fe(kappa(2) -odt)(CO)(2){kappa(2) -(Ph2P)(2)N(CH2)(3)Me} (2). The crystal structure of 1 contains a butterfly [Fe2S2] cluster, whereas that of 2 exhibits a square bipyramidal geometry of Fe atom.