(C4H12N2)[CoCl4]: tetrahedrally coordinated Co2+ without the orbital degeneracy

We report on the synthesis, crystal structure and magnetic properties of a previously unreported Co(2+) S = 3/2 compound, (C4H12N2)[CoCl4], based upon a tetrahedral crystalline environment. The S = 3/2 magnetic ground state of Co(2+), measured with magnetization, implies an absence of spin-orbit coupling and orbital degeneracy. This contrasts with compounds based upon an octahedral and even known tetrahedral Co(2+) [Cotton et al. (1961). J. Am. Chem. Soc. 83, 4690] systems where a sizable spin-orbit coupling is measured. The compound is characterized with single-crystal X-ray diffraction, magnetic susceptibility, IR and UV-vis spectroscopy. Magnetic susceptibility measurements find no magnetic ordering above 2 K. The results are also compared with the previously known monoclinic hydrated analogue.