Crystal and supramolecular structures of dioxomolybdenum(VI) and dioxotungsten(VI) complexes of dihydroxybenzoic acids

The tetramethylammonium salts (NMe4)2[MO2(2,3-Hdhb)2]·2H2O and (NMe4)2[MO2(3,4-Hdhb)2]·6H2O (M = Mo, W; Hdhb = monoprotonated form of 2,3- or 3,4-dihydroxybenzoic acid, 2,3-H3dhb or 3,4-H3dhb) were prepared and their crystal structures determined. The structure of [Mg(H2O)6](NMe4)4[MoO2(3,4-dhb)(3,4-Hdhb)]2·13H2O, obtained by the recrystallization of (NMe4)2[MoO2(3,4-Hdhb)2] in the presence of magnesium ions, is also reported. The supramolecular interactions of the five structures are discussed in detail concerning the hydrogen bonding patterns involving complexes and water molecules of crystallization.

Graphical abstractThe synthesis, detailed crystallization procedures, crystal and molecular structures of five mononuclear molybdenum/tungsten complexes of 2,3- and 3,4-dihydroxybenzoic acids are described. Each structure contains only one of the three possible geometric isomers. The supramolecular hydrogen-bonded networks promoted by the complexes and co-crystallized molecular species have been examined in detail.Figure optionsDownload full-size imageDownload as PowerPoint slide