title: Apparent or real water exchange reactions on [Zn(H2O)4(L)](2+)·2H2O (L = sp-nitrogen donor ligands)? A quantum chemical investigation.
abstract: The exchange of a second coordination sphere water molecule in [Zn(H(2)O)(4)(L)](2+)·2H(2)O (L = HN(3), HCN, FCN, ClCN, BrCN, CH(3)CN, (C(4)H(3))CN, PhCN, (CH(3))(3)CCN, CF(3)CN, CCl(3)CN, CHCl(2)CN, and CH(2)ClCN) against a coordinated water molecule was studied by quantum chemical calculations (RB3LYP/6-311+G**). The complete reaction consists of an associative binding of one H(2)O from the second coordination sphere leading to a six-coordinate intermediate [Zn(H(2)O)(5)(L)](2+)·H(2)O, followed by the dissociation of a water molecule to reach the product state [Zn(H(2)O)(4)(L)](2+)·2H(2)O. For a real water exchange reaction to occur two different transition states have to be included, otherwise only an apparent water exchange reaction takes place. For the water exchange reaction in [Zn(H(2)O)(4)(L)](2+)·2H(2)O, nearly iso-energetic cis- and trans-orientated transition states are crossed. The gas-phase proton affinity of L shows instructive correlations with structural parameters and energy gaps for the investigated reactions.
authors.affiliation: Inorganic Chemistry, Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, Egerlandstr. 1, 91058 Erlangen, Germany.
authors.forename: Basam M
authors.initials: BM
authors.lastname: Alzoubi
authors.forename: Markus
authors.initials: M
authors.lastname: Walther
authors.forename: Ralph
authors.initials: R
authors.lastname: Puchta
authors.forename: Rudi
authors.initials: R
authors.lastname: van Eldik
mesh_terms: D008024:Ligands; D009584:Nitrogen / Q000737:chemistry*; D011789:Quantum Theory; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: D008024:Ligands; D014867:Water; D015032:Zinc; D009584:Nitrogen