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The potentially terdentate ligand 1-(S-methyldithio)-3,5-dimethyl-3-(S-methyldithiocarbazato)pyrazoline (H2mdp) was prepared by the reaction of S-methyldithiocarbazate with acetylacetone in an acidic ethanol solution. The neutral complex [TcOCl(mdp)](1) was formed by the reaction of (n-Bu4N)[TcOCl4] with H2mdp in ethanol at room temperature. Compound 1 has a square-pyramidal geometry with the thiolate, thiocarbonyl and amide donor atoms of the terdentate chelate mdp and chloride forming a square plane, with the oxo oxygen in the apical position.

The neutral complex [TcOCl(hdc)] (1) (hdc = S-methyl-β-N-(2-hydroxyphenylethylidene)dithiocarbazate) was prepared by reaction of (n-Bu4N)[TcOCl4] with an equimolar amount of H2hdc in ethanol/dichloromethane at room temperature. With a fourfold mol excess of H2hdc in methanol/acetone, the ‘3 + 2’ complex [TcO(hdc)(adc)] (2) (adc = S-methyl-β-N-(prop-2-ylidene)dithiocarbazate) was isolated. Adc was formed by ketone exchange between solvent acetone and the hydroxyacetophenone fragment of hdc. Compounds 1 and 2 were characterized by infrared spectroscopy, 1H NMR spectrometry, elemental analysis and single-crystal X-ray crystallography. Complex 1 has square-pyramidal geometry with the SNO-donor atoms of the tridentate chelate hdc and chloride forming a square plane, with the oxo oxygen atom in the apical position. Complex 2 has a distorted octahedral geometry, with an S2N2 donor set in the equatorial plane and the oxo and phenolate oxygen atoms in trans apical positions.