Chemistry of the binary mixture of 1,10-phenanthroline and zinc perchlorate hexahydrate in methanol and gas phase. Monohydroxo species and tricoordination of zinc and water clusters

Abstract ESIMS reveals that methanol solutions of 1:1, 1:2 and 1:3 mixtures of Zn(ClO4)2 · 6H2O and 1,10-phenanthroline (phen) generate [Zn(phen)(OH)]+, [Zn(phen)(H2O)4(OH)]+, [Zn(phen)2(H2O)(OH)]+and [Zn(phen)2(H2O)4(OH)]+ ions in the gas phase. DFT calculations at the B3LYP/LanL2DZ level show that zinc is planar tricoordinate in [Zn(phen)(OH)]+ and the cis configuration is more stable than the trans one for the hexacoordinate ion [Zn(phen)2(H2O)(OH)]+. DFT calculations also show that the [Zn(phen)(H2O)4(OH)]+ and [Zn(phen)2(H2O)4(OH)]+ ions are actually [Zn(phen)(H2O)(OH)]+ · 3H2O and [Zn(phen)2(H2O)(OH)]+ · 3H2O containing extended motifs of H-bonded water clusters. The aqua species corresponding to the monohydroxo ions are acidic. Their acid dissociations are modeled collectively by equilibrium (see below) where other ligands around Zn are not specified. An attempt is then made to estimate Ka