Modeling [FeFe] hydrogenase: Synthesis and protonation of a diiron dithiolate complex containing a phosphine-N-heterocyclic-carbene ligand

The ligand exchange reaction of I-Me-(CH2) (2)-PPh2 (I-Me = 1-methyimidazol-2-ylidene) and the hexacarbonyl complex [{Fe-2{mu-S(CH2)(3)S}(CO)(6)] (1) resulted in the formation of the chelated complex [{Fe-2{mu-S(CH2)(3)S}(CO)(4)(I-Me-(CH2)(2)-PPh2)] (2). The molecular structure of 2 was confirmed by spectroscopic and X-ray analyses. This complex catalyzes proton reduction. Low temperature NMR studies on the protonation of 2 revealed the formation of a terminal hydride intermediate. (C) 2009 Elsevier B.V. All rights reserved.