title: Atomic partitioning of M-H2 bonds in [NiFe] hydrogenase--a test case of concurrent binding.
abstract: The possibility of simultaneous addition of η(2)-H2 to both the metals (Ni and Fe) in the active site of the as isolated state of the enzyme (Ni-SI) is examined here by an atom-by-atom electronic energy partitioning based on the QTAIM method. Results show that the 4LS state prefers H2 removal than addition. Destabilization of the atomic basins of the thiolate bridges and decrease of the electrophilicity of the Fe and Ni, resulting in poor back donation to the CO ligand, are the bottlenecks that hamper dihydrogen activation simultaneously. The study helps to understand why such states are seldom accessed in the activation of dihydrogen. Moreover, Ni has been found to be the natural choice for the dihydrogen binding.
authors.affiliation: Theoretical & Computational Chemistry Laboratory, School of Chemistry, Bharathidasan University, Tiruchirappalli 24, India. venuvanalingam@yahoo.com.
authors.forename: Swaminathan Angeline
authors.initials: SA
authors.lastname: Vedha
authors.forename: Rajadurai Vijay
authors.initials: RV
authors.lastname: Solomon
authors.forename: Ponnambalam
authors.initials: P
authors.lastname: Venuvanalingam
mesh_terms: D001665:Binding Sites; D002248:Carbon Monoxide / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry* / Q000378:metabolism; D006864:Hydrogenase / Q000737:chemistry* / Q000378:metabolism; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D009532:Nickel / Q000737:chemistry* / Q000378:metabolism; D011789:Quantum Theory
chemical_list: D009532:Nickel; D002248:Carbon Monoxide; D006859:Hydrogen; D007501:Iron; C043296:nickel-iron hydrogenase; D006864:Hydrogenase