Synthesis and Characterization of New 2D Coordination Polymers based on Mn(NCS)2 and Ni(NCS)2 with 1, 2‐Bis(4‐pyridyl)‐ethane as Co‐Ligand

Abstract

AbstractReaction of manganese(II) and nickel(II) thiocyanate with 1, 2‐bis(4‐pyridyl)‐ethane (bpa) leads to the formation of literature known compounds of composition M(NCS)2(bpa)2 with M = Mn (1‐Mn) and Ni (1‐Ni). On heating 1‐Mn and 1‐Ni transform into new compounds of composition M(NCS)2(bpa) with M = Mn (2‐Mn) and Ni (2‐Ni). These compounds can also be prepared in solution. In both synthetic routes only microcrystalline powders are obtained with crystals too small for single‐crystal X‐ray diffraction. Therefore, the structures of both compounds were solved and refined from X‐ray powder data. In the crystal structure the transition metal cations are coordinated by two bpa co‐ligands and four thiocyanato anions within slightly distorted octahedra. The metal cations are linked by μ‐1, 3‐bridging thiocyanato anions into chains, that are further connected into layers by the bpa ligands. Magnetic measurements on 2‐Ni shows only Curie‐Weiss paramagnetism. In contrast, for 2‐Mn an antiferromagnetic ordering is observed but on further cooling the susceptibility curves increase indicating for canted antiferromagnetism. Further measurements prove that the increase at lower temperatures can be traced back to a small contamination with 1‐Mn, which is always present independent if this compound is prepared by thermal decomposition or by crystallization from solution. In the course of the crystallization experiments a few single crystals of two additional compounds of composition Mn(NCS)2(bpa)(H2O)2 (3‐Mn) and [Mn(NCS)2]2(bpa)3(CH3OH)2 (4‐Mn) were accidently obtained and characterized by single crystal structure analysis. The results of the magnetic measurements are compared with those for related compounds with different neutral N‐donor ligands.