Crystal structure and ferromagnetism of (n-C₃H₇)₄N[Co^IIFe^III(dto) ₃] (dto = C₂O₂S₂)

Recently, we have discovered a new type of first order phase transition around 120K for (n-C₃H₇)₄N[Fe^IIFe^III(dto) ₃] (dto = C₂O₂S₂), where the charge transfer transition between Fe^II and Fe^III occurs reversibly. In order to elucidate the origin of this peculiar first order phase transition. Detailed information about the crystal structure is indispensable. We have synthesized the single crystal of (n-C₃H₇)₄N[Co^IIFe^III(dto) ₃] whose crystal structure is isomorphous to that of (n-C₃H₇)₄N[Fe^IIFe^III(dto) ₃], and determined its detailed crystal structure. Crystal data: space group P6₃, a = b = 10.044(2) Å, c = 15.960(6)Å, α = β = 90°, γ = 120°, Z = 2 (C₁₈H₂₈NS₆O₆FeCo). In this complex, we found a ferromagnetic transition at T_c = 3.5 K. Moreover, on the basis of the crystal data of (n-C₃H₇)₄N[Co^IIFe^III(dto) ₃], we determined the crystal structure of (n-C₃H₇)₄N[Fe^IIFe^III(dto) ₃] by simulation of powder X-ray diffraction results.