First Row Transition Metal(II) Thiocyanate Complexes, and Formation of 1-, 2-, and 3-Dimensional Extended Network Structures of M(NCS)2(Solvent)2 (M = Cr, Mn, Co) Composition

The reaction of first row transition M-II ions with KSCN in various solvents form tetrahedral (NMe4)(2)[M-II(NCS)(4)] (M = Fe, Co), octahedral trans-M-II(NCS)(2)(Sol)(4) (M = Fe, V, Ni; Sol = MeCN, THF), and K-4[M-II(NCS)(6)] (M = V, Ni). The reaction of M(NCS)(2)(OCMe2)(2) (M = Cr, Mn) in MeCN and [Co(NCMe)(6)](BF4)(2) and KSCN in acetone and after diffusion of diethyl ether form M(NCS)(2)(Sol)(2) that structurally differ as they form one-dimensional (1-D) (M = Co; Sol = THF), two-dimensional (2-D) (M = Mn; Sol = MeCN), and three-dimensional (3-D) (M = Cr; Sol = MeCN) extended structures. 1-D Co(NCS)(2)(THF)(2) has trans-THFs, while the acetonitriles have a cis geometry for 2- and 3-D M(NCS)(2)(NCMe)(2) (M = Cr, Mn). 2-D Mn(NCS)(2)(NCMe)(2) is best described as Mn-II(mu(N,N)-NCS)(mu(N,S)-NCS)(NCMe)(2) [= Mn-2(mu(N,N)-NCS)(2)(mu(N,S)-NCS)(2)(NCMe)(4)] with the latter mu(N,S)-NCS providing the 2-D connectivity. In addition, the reaction of Fe(NCS)(2)(OCMe2)(2) and 7,7,8,8-tetracyanoquinop-p-dimethane (TCNQ) forms 2-D structured Fe-II(NCS)(2)TCNQ The magnetic behavior of 1-D Co(NCS)(2)(THF)(2) can be modeled by a 1-D Fisher expression (H = 2JS(i).S-j) with g = 2.4 and J/k(B) = 0.68 K (0.47 cm(-1)) and exhibit weak ferromagnetic coupling. Cr(NCS)(2)(NCMe)(2) and Fe-II(NCS)(2)TCNQ magnetically order as antiferromagnets with T-c's of 37 and 29 K, respectively, while Mn(NCS)(2)(NCMe)(2) exhibits strong antiferromagnetic coupling. M(NCS)(2)(THF)(4) and K-4[M(NCS)(6)] (M = V, Ni) are paramagnets with weak coupling between the octahedral metal centers.