Cyano-Bridged Bimetallic Assemblies from Hexacyanometalate, [M(CN)₆]^3- (M = Mn^III and Fe^III), and [M(N₄-macrocycle)]²⁺ (M = Fe^III, Ni^II and Zn^II) Building Blocks. Syntheses, Multidimensional Structures, and Magnetic Properties

Reactions between [M(N4-macrocycle)]2+ (M = ZnII and NiII; macrocycle ligands are either CTH = d,l-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane or cyclam = 1,4, 8, 11-tetrazaazaciclotetradecane) and [M(CN)6]3- (M = FeIII and MnIII) give rise to cyano-bridged assemblies with 1D linear chain and 2D honeycomblike structures. The magnetic measurements on the 1D linear chain complex [Fe(cyclam)][Fe(CN)6]·6H2O 1 points out its metamagnetic behavior, where the ferromagnetic interaction operates within the chain and the antiferromagnetic one between chains. The Neel temperature, TN, is 5.5 K and the critical field at 2 K is 1 T. The unexpected ferromagnetic intrachain interaction can be rationalized on the basis of the axially elongated octahedral geometry of the low spin FeIII ion of the [Fe(cyclam)]3+ unit. The isostructural substitution of [Fe(CN)6]3- by [Mn(CN)6]3- in the previously reported complex [Ni(cyclam)]3[Fe(CN)6]2·12H2O 2 leads to [Ni(cyclam)]3[Mn(CN)6]2·16 H2O 3, which exhibits a corrugated 2D honeycomblike structure and a metamagnetic behavior with TN = 16 K and a critical field of 1 T. In the ferromagnetic phase (H > 1 T) this compound shows a very important coercitive field of 2900 G at 2 K. Compound [Ni(CTH)]3[Fe(CN)6]2·13H2O 4, C60H116Fe2N24Ni3O13, monoclinic, A 2/n, a = 20.462(7), b = 16.292(4), c = 27.262(7) Å, β = 101.29(4)°, Z = 4, also has a corrugated 2D honeycomblike structure and a ferromagnetic intralayer interaction, but, in contrast to 2 and 3, does not exhibit any magnetic ordering. This fact is likely due to the increase of the interlayer separation in this compound. {[Zn(cyclam)Fe(CN)6Zn(cyclam)] [Zn(cyclam)Fe(CN)6]·22H2O·EtOH} 5, C44H122Fe2N24O23Zn3, monoclinic, A 2/n, a = 14.5474(11), b = 37.056(2), c = 14.7173(13) Å, β = 93.94(1)°, Z = 4, presents an unique structure made of anionic linear chains containing alternating [Zn(cyclam)]2+ and [Fe(CN)6]3- units and cationic trinuclear units [Zn(cyclam)Fe(CN)6Zn(cyclam)]+. Their magnetic properties agree well with those expected for two [Fe(CN)6]3- units with spin−orbit coupling effect of the low spin iron(III) ions.