Compounds with symmetrical tricobalt chains wrapped by dipyridylamide ligands and cyanide or isothiocyanate ions as terminal ligands

Three new linear compounds of the type Co-3(dpa)(4)X-2, where dpa is the an ion of di(2-pyridyl)amine and X is NCS- (5), CN- (6), and N(CN)(2)(-) (7), have been prepared, and their structures and magnetic behavior have been st udied. In all of them, including three different solvates of 5, the Co3 cha ins are symmetrical with Co-Co distances of ca. 2.31-2.32 Angstrom. The app earance of four lines in the H-1 NMR spectra of the three compounds is also consistent with a symmetrical structure in solution. For all compounds, th e magnetic behavior is quite similar with mu (eff) of ca. 1.9-2.0 mu (B) at temperatures between 1.8 and 200 K. As the temperature increases, the effe ctive moments increase gradually, but since saturation is not reached, even at 400 K, the high-spin state cannot be assigned.