b ) Facultad de Farmacia, Universidad Alfonso X el Sabio, ES-28691 Villanueva de la Cañ ada (Madrid) c ) ICAI, Universidad Pontificia de Comillas, ES-28015 MadridWe describe the synthesis, characterization by IR and electronic spectra, magnetic susceptibility measurements, analytical data, kinetic study by differential-scanning calorimetry, and thermogravimetric analysis of the thermal decomposition under N 2 of the adducts 2 -7 with pyridine or substituted pyridines of bis(piperidine-1-carbodithioato-kS,kS')di-m-thioxodithioxoditungsten(V) (1), to which the general formula [W 2 B 2 (pipCS 2 ) 2 S 2 (m-S) 2 ] is assigned (pipCS 2 ¼ piperidine-1-carbodithioato and B ¼ pyridine (py), 3-methylpyridine (3-Mepy), 4-methylpyridine (4-Mepy), 3,5-dimethylpyridine (3,5-Me 2 py), pyridin-3-amine (3-pyNH 2 ), and pyridin-4-amine (4-pyNH 2 )). For the endothermic process of loss of the coordinated base B, we calculated activation energies with a method reported previously by us; the mechanism and pre-exponential Arrhenius factor of this reaction were also determined. A relationship between the pyridines basicity, IR and electronic spectral data, and activation energies was established.