On the structures and properties of Cr(DMSO)6 3+ and the coordination polymer [cis-Cr(III)(oxalate)2(DMSO)2K(DMSO)2]n

cis-Cr(III)(oxalate)2(DMSO)2K(DMSO)2 was formed by K3Cr(oxalate)3 in dimethylsulfoxide–THF mixtures. The structure is ribbon-like with cis-Cr(oxalate)2(DMSO)2 − complex ions bridged by oxalates to (DMSO)K(DMSO)2K(DMSO) units forming interconnected rings of six metal complexes. In the same type of solutions Cr(DMSO)6(NO3)3 was also formed. In this structure Cr(III) is six-coordinated by oxygens from DMSO. Cr(DMSO)6(NO3)3 is isostructural with Fe(DMSO)6(NO3)3 (J.R. Tzou et al., Acta Crystallogr., Sect. C, 51 (1995) 2249). The Cr(III)O distance shows an expected shortening of about 0.04 Å compared to the Fe(III)O bond in Fe(DMSO)6(NO3)3.