Synthesis, crystal growth, and optical and magnetic properties of three bimetallic thiocyanates TBi(SCN)(5) T = Mn, Cd and FeBi(SCN)(6).

In this work, we report the synthesis, crystal growth, and optical and magnetic properties of two new isotypic bimetallic thiocyanates, MnBi(SCN) and CdBi(SCN). The crystal structure of MnBi(SCN) and CdBi(SCN) was determined by single-crystal X-ray diffraction. MnBi(SCN) and CdBi(SCN) crystallize in the triclinic space group 1̄ (no. 2) with unit cell parameters of = 8.0498(5) Å, = 9.2749(5) Å, = 10.7779(8) Å, = 72.752(6)°, = 68.422(6)°, = 87.908(5)° and = 8.1528(5) Å, = 9.4008(7) Å, = 10.9513(8) Å, = 73.212(6)°, = 67.963(6)°, = 87.879(6)°, respectively. The structure of MnBi(SCN) and CdBi(SCN) contains a three-dimensional (3D) network consisting of pairs of edge-sharing [TN] T = Mn, Cd octahedra linked through the thiocyanate ligand to similar pairs of edge-sharing [BiS] octahedra. A known related structure to this is that of FeBi(SCN), which features a perovskite-like structure consisting of corner-sharing [FeN] and [BiS] octahedra. In this work, the magnetic properties of MnBi(SCN) and the previously reported FeBi(SCN) were investigated, with the former being found to order antiferromagnetically with a Néel temperature around 12 K. FeBi(SCN) was found to exhibit no magnetic ordering down to 2 K, although isothermal magnetization data indicate that it may order ferromagnetically below 2 K. Density functional theory (DFT) was also employed to explore the electronic structure of MnBi(SCN), which reveals that the Bi-S and Mn-N interactions are crucial for controlling the optical properties of MnBi(SCN). MnBi(SCN) was predicted to be an indirect-gap semiconductor with a bandgap of 2.7 eV, which was reasonably consistent with the UV-vis spectrum measurement of 2.1 eV.