Reactivity of benzil bis(4-methyl-3-thiosemicarbazone) with cadmium nitrate. Crystal structure of [Cd(LMe2H4)(NO3)2][Cd(LMe2H4)(NO3)(H2O)]NO3 · H2O

The reaction between cadmium nitrate dihydrate and benzil bis(4-methyl-3-thiosemicarbazone), LMe2H4, depends on the working conditions. In methanol the reaction gives the novel complex [Cd(LMe2H4)(NO3)2][Cd(LMe2H4)(NO3)(H2O)]NO3 · H2O (1). Its crystal structure shows the presence of two cadmium atoms with different coordination numbers, seven and eight, and the ligands acting as N2S2 neutral molecules. One cadmium has the coordination sphere completed by a bidentate nitrato group and a water molecule, whereas the other one is bonded to two bidentate nitrato groups. Both molecules are joined to one nitrate ion and to an additional water molecule by hydrogen bonds. In the presence of lithium hydroxide, the reaction leads to a binuclear complex with the ligand doubly deprotonated [Cd(LMe2H2)]2 (2). The complexes were characterized by elemental analysis, mass spectrometry, 13C and 113Cd CP/MAS NMR and, in the case of complex 1, by X-ray diffraction.

Graphical abstractBenzil bis(4-methyl-3-thiosemicarbazone) and cadmium nitrate form, depending on the pH, two new complexes: [Cd(LMe2H4)(NO3)2][Cd(LMe2H4)(NO3)(H2O)]NO3 · H2O (1) and [Cd(LMe2H4)]2 (2). Complex 1 contains two different types of Cd(II) ions. The Cd(1) atom is seven-coordinate with a S2N2O3 coordination sphere, but the coordination number of the Cd(2) atom expands to eight by an additional oxygen atom. Both units are linked by hydrogen bonds.Figure optionsDownload full-size imageDownload as PowerPoint slide