Kristallzucht und Neubestimmung der Kristallstruktur von μ-Pyrazino-kobalt(II)-chlorid, CoCl2(pyz)2

Single crystals of CoCl 2 (pyz) 2 were prepared for the first time by sol-gel technique using pyrazine in tetramethoxysilane (TMOS) as the gel-forming reagent. The red polymeric Co(II) complex crystallizes in the orthorhombic space group Ccca with lattice parameters a= 10.100(1)A, b= 10.672(1)A, c= 10.136(1)A and Z = 4 formula units, which is in contrast to its former structural description in the tetragonal system. The structure consists of infinite Co(pyz) 2 layers parallel (010) with a square planar Co-N 4 coordination completed to a nearly undistorted square bipyramide by the two chloro ligands.