Structural, spectroscopic and computational studies of the HgL2Cl2 complex (L=3,5-dimethyl-1-thiocarboxamide pyrazole) and the crystal structure of L

In the present paper we report the synthesis as well as the structural and vibrational characterisation of the HgL2Cl2 complex ( L = 3,5-dimethyl-1-thiocarboxamide). The crystal and molecular structures of both L and the HgL2Cl2 complex were determined by single-crystal X-ray diffraction. The coordination propensity of L to HgCl2 was explored by quantum chemical calculations. We found the preference of the monodentate coordination of L to HgCl2 through the sulfur atom ( instead of the "pyridine'' nitrogen) to be in agreement with Pearson's acid - base character of the atoms involved and the steric effects. The vibrational properties of HgL2Cl2 were evaluated by a joint FT-IR and quantum chemical analysis. In addition, the thermal decomposition of the complex and ligand is reported

Probing intermetallic coupling in dinuclear N-heterocyclic carbene ruthenium(II) complexes

A series of bimetallic N-heterocyclic carbene (NHC) ruthenium(II) complexes were synthesized, which comprise two [RuCl₂(cymene)(NHC)] units that are interlinked via the NHC nitrogens by alkyl chains of different length. Electrochemical characterization revealed two mutually dependent oxidation processes for the complex with a methylene linker, indicating moderate intramolecular electronic coupling of the two metal centers (class II system). The degree of coupling decreases rapidly upon increasing the number of CH₂ units in the linker and provides essentially decoupled class I species when propylene or butylene linkers are used. Electrochemical analyses combined with structural investigations suggest a through-bond electronic coupling. Replacement of the alkyl linker with a p-phenylene group afforded cyclometalated complexes, which were considerably less stable. The electronic coupling in the methylene-linked complex and the relatively robust NHC–ruthenium bond may provide access to species that are switchable on the molecular scale