Synthesis and characterization of [M(DMSO)6][SnCI6] complexes (M = Fe2+, Co2+, and Ni2+) -: An old mystery solved

The synthesis of an unknown Fe(II) complex originally reported in 1973 and formulated then as [Fe(DMSO)(5)Cl][SnCl4(]) was thoroughly reproduced and the compound reformulated as the novel [Fe(DMSO)(6)][SnCl6] double complex salt. Current elemental analysis and IR and Mossbauer spectroscopy matched the original 1973 data, and Raman spectroscopy and single crystal X-ray diffraction provided additional confirmation of our reformulation. [Fe(DMSO)(6)][SnCl6] (1) crystalizes in the trigonal space group R (3) over bar with octahedral [Fe(DMSO)(6)](2+) and [SnCl6](2+) complex ions with an Fe-O bond length of 2.121(3) angstrom. The same synthesis was extended to Co(II) and Ni(II) to generate the novel [Co(DMSO)(6)][SnCl6] (2), which crystallizes in the triclinic space group P (1) over bar with a Co-O bond length of 2.093(4)-2.113(5) angstrom, and [Ni(DMSO)(6)][SnCl6] (3), which crystallized in the trigonal R (3) over bar space group and has a NiO bond length of 2.062(2) angstrom. The Sn-Cl bond length in all three complexes ranged from 2.421(2) to 2.448(2) angstrom.