Hydrogenases catalyze the reversible oxidation of dihydrogen to protons and electrons. The structures of two Fe-only hydrogenases have been recently reported [Peters, J. W.; Lanzilotta, W. N.; Lemon, B. J.; Seefeldt, L. C. Science 1998, 282, 1853-1858. Nicolet, Y.; Piras, C.; Legrand, P.; Hatchikian, E. C.; Fontecilla-Camps, J, C. Structure 1999, 7, 13-23], showing that the likely site of dihydrogen activation Is the so-called [2Fe](H) cluster, where each Fe ion is coordinated by CO and CN- ligands and the two metals are bridged by a chelating S-X-3-S ligand. Moreover, the presence of a water molecule coordinated to the distal Fe2 center suggested that the Fe2 atom could be a suitable site for binding and activation of H-2. In this contribution, we report a density functional theory investigation of the structural and electronic properties of complexes derived from the [(CO)(CH3S)(CN)Fe(II)(mu-PDT)Fe(II)(CO)(2)(CN)](-1) species, which is related to the [2Fe]H cluster observed in Fe-only hydrogenases. Our results show that the structure of the [2Fe](H) cluster observed in the enzyme does not correspond to a stable form of the isolated cluster, in the absence of the protein. As a consequence, the reactivity of [(CO)(CH3S)(CN)Fe(II) (mu-PDT)Fe(II)(CO)(2)(CN)](-1) derivatives in solution may be expected to be quite different from that of the active site of Fe-only hydrogenases. In fact, the most favorable path for H-2 activation Involves the two meta[ atoms and one of the bridging S atoms and is associated with a very low activation energy (5.3 kcal mol(-1)). The relevance of these observations for the catalytic properties of Fe-only hydrogenases is discussed in light of available experimental and theoretical data
Bruschi, M., Fantucci, P., De Gioia, L. (2002). DFT investigation of structural, electronic, and catalytic properties of diiron complexes related to the [2Fe]H subcluster of Fe-only hydrogenases. INORGANIC CHEMISTRY, 41(6), 1421-1429 [10.1021/ic010770r].
DFT investigation of structural, electronic, and catalytic properties of diiron complexes related to the [2Fe]H subcluster of Fe-only hydrogenases
Bruschi, M;Fantucci, P;De Gioia, L.
2002
Abstract
Hydrogenases catalyze the reversible oxidation of dihydrogen to protons and electrons. The structures of two Fe-only hydrogenases have been recently reported [Peters, J. W.; Lanzilotta, W. N.; Lemon, B. J.; Seefeldt, L. C. Science 1998, 282, 1853-1858. Nicolet, Y.; Piras, C.; Legrand, P.; Hatchikian, E. C.; Fontecilla-Camps, J, C. Structure 1999, 7, 13-23], showing that the likely site of dihydrogen activation Is the so-called [2Fe](H) cluster, where each Fe ion is coordinated by CO and CN- ligands and the two metals are bridged by a chelating S-X-3-S ligand. Moreover, the presence of a water molecule coordinated to the distal Fe2 center suggested that the Fe2 atom could be a suitable site for binding and activation of H-2. In this contribution, we report a density functional theory investigation of the structural and electronic properties of complexes derived from the [(CO)(CH3S)(CN)Fe(II)(mu-PDT)Fe(II)(CO)(2)(CN)](-1) species, which is related to the [2Fe]H cluster observed in Fe-only hydrogenases. Our results show that the structure of the [2Fe](H) cluster observed in the enzyme does not correspond to a stable form of the isolated cluster, in the absence of the protein. As a consequence, the reactivity of [(CO)(CH3S)(CN)Fe(II) (mu-PDT)Fe(II)(CO)(2)(CN)](-1) derivatives in solution may be expected to be quite different from that of the active site of Fe-only hydrogenases. In fact, the most favorable path for H-2 activation Involves the two meta[ atoms and one of the bridging S atoms and is associated with a very low activation energy (5.3 kcal mol(-1)). The relevance of these observations for the catalytic properties of Fe-only hydrogenases is discussed in light of available experimental and theoretical data
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