Extended Network Thiocyanate- and Tetracyanoethanide-Based First-Row Transition Metal Complexes

Linear chain thiocyanate complexes of M­(NCS)2(OCMe2)2 (M = Fe, Mn, Cr) composition have been prepared and structurally, chemically, and magnetically characterized. Fe­(NCS)2(OCMe2)2 exhibits metamagnetic-like behavior, and orders as an antiferromagnet at 6 K. The Mn and Cr compounds are antiferromagnets with Tc of 30 and 50 K, respectively, with J/kB = −3.5 (−2.4 cm–1) and −9.9 K (−6.9 cm–1), respectively, when fit to one-dimensional (1-D) Fisher chain model (H = −2JSi·Sj). Co­(NCS)2 was prepared by a new synthetic route, and powder diffraction was used to determine its structure to be a two-dimensional (2-D) layer with μN,S,S-NCS motif, and it is an antiferromagnet (Tc = 22 K; θ = −33 K for T > 25 K). M­(NCS)2(OCMe2)2 (M = Fe, Mn) and Co­(NCS)2 react with (NBu4)­(TCNE) in dichloromethane to form M­(TCNE)­[C4(CN)8]1/2, and in acetone to form M­[C4(CN)8]­(OCMe2)2 (M = Fe, Mn, Co). These materials possess μ4-[C4(CN)8]2– that form 2-D layered structural motifs, which exhibit weak antiferromagnetic coupling. Co­(TCNE)­[C4(CN)8]1/2 behaves as a paramagnet with strong antiferromagnetic coupling (θ = −50 K).