(C${}_4$H${}_{12}$N${}_2$)[CoCl${}_4$] -tetrahedrally coordinated Co${}^{2+}$ without the orbital degeneracy

Abstract

We report on the synthesis, crystal structure, and magnetic properties of a previously unreported Co${}^{2+}$ $S=\frac{3}{2}$ compound, (C${}_4$H${}_{12}$N${}_2$)[CoCl${}_4$], based upon a tetrahedral crystalline environment. The $S=\frac{3}{2}$ 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 octrahedral and even known tetrahedral Co${}^{2+}$ based systems where a sizable spin-orbit coupling is measured. The compound is characterized with single crystal x-ray diffraction, magnetic susceptibility, infrared, and ultraviolet/visible spectroscopy. Magnetic susceptibility measurements find no magnetic ordering above 2 K. The results are also compared with the previously known monoclinic hydrated analogue.

(5 pages, 4 figures)