[Fe(bpb)(CN)₂]^-as a Versatile Building Block for the Design of Novel Low-Dimensional Heterobimetallic Systems:  Synthesis, Crystal Structures, and Magnetic Properties of Cyano-Bridged Fe^III−Ni^IIComplexes [(bpb)^2-= 1,2-Bis(pyridine-2-carboxamido)benzenate]

Abstract

A dicyano-containing [Fe(bpb)(CN)2]- building block has been employed for the synthesis of cyano-bridged heterometallic Ni(II)-Fe(III) complexes. The presence of steric bpb(2-) ligand around the iron ion results in the formation of low-dimensional species: five are neutral NiFe2 trimers and three are one-dimensional (1D). The structure of the 1D complexes consists of alternating [NiL]2+ and [Fe(bpb)(CN)2]- generating a cyano-bridged cationic polymeric chain and the perchlorate as the counteranion. In all complexes, the coordination geometry of the nickel ions is approximately octahedral with the cyano nitrogen atoms at the trans positions. Magnetic studies of seven complexes show the presence of ferromagnetic interaction between the metal ions through the cyano bridges. Variable temperature magnetic susceptibility investigations of the trimeric complexes yield the following J(NiFe) values (based on the spin exchange Hamiltonian H = -2J(NiFe) S(Ni) (S(Fe(1)) + S(Fe(2))): J(NiFe) = 6.40(5), 7.8(1), 8.9(2), and 6.03(4) cm(-1), respectively. The study of the magneto-structural correlation reveals that the cyanide-bridging bond angle is related to the strength of magnetic exchange coupling: the larger the Ni-N[triple bond]C bond angle, the stronger the Ni- - -Fe magnetic interaction. One 1D complex exhibits long-range antiferromagnetic ordering with T(N) = 3.5 K. Below T(N) (1.82 K), a metamagnetic behavior was observed with the critical field of approximately 6 kOe. The present research shows that the [Fe(bpb)(CN)2]- building block is a good candidate for the construction of low-dimensional magnetic materials.

Syntheses and crystal structures of four cyanide-bridged trinuclear iron(III)–copper(II)–iron(III) complexes exhibiting abnormal antiferromagnetic coupling

“…Based on the above magneto-structural correlation for cyanide-bridged Fe I -Cu II systems, one can draw the conclusion that the critical angle between ferromagnetic and antiferromagnetic is 144.1°, which agrees well with the experimental results. This result is also comparable to that of cyanide-bridged Fe I -Ni II , Cr I -Ni II and Cr IMn II systems reported by our group previously [19][20][21].…”

“…Therefore, a large number of cyanide-bridged M I -M 0 (M = Fe, Cr, Ru and Mn; M 0 = Cu II , Ni II , Mn II , Mn I , etc.) compounds with different molecular topological structures and interesting physical properties have been reported [13][14][15][16][17][18][19][20][21]. In addition, the magneto-structural correlation is one of the most basic scientific problems in the field of molecular magnetism.…”

A series of trinuclear sandwich-like cyanide-bridged iron(III)-manganese(II) complexes: synthesis, crystal structures, and magnetic properties

“…The two trans cyanide groups are predisposed to act as mono-or bidentate ligands toward other metal centers. The results reported by our group further illustrate that they are suitable building blocks for the assembly of low-dimensional heterometallic cyanide-bridged magnetic complexes with various topologies, including binuclear and arc-like tetranuclear clusters, 1D chains, and nanosized molecular wheels [17][18][19][20]. To throw further light on the systems based on pyridinecarboxamide trans-dicyanidemetalate building blocks (Scheme 1), we investigated the reactions of these types of cyanide precursors with the manganese(III) compound [Mn(acac) 2 ]Cl (acac = acetylacetate) In this paper, we present our recent work that concerns the synthesis, crystal structures, and magnetic properties of four trinuclear sandwich-like heterometallic cyanide-bridged…”

“…In our recent works [17][18][19][20]23], pyridinecarboxamide trans-dicyanidemetalate building blocks have been successfully employed to construct cyanide-bridged heterometallic complexes with interesting magnetic properties by using Mn(III) compounds of salen-type Schiff base ligands, seven-coordinate macrocyclic manganese(II) compounds, or polyaza-Ni(II) complexes as assembling segments, indicating that these types of cyanide precursors are good candidates for the synthesis of low-dimensional cyanidebridged complexes. In the present study, Table 2, the Fe-C:N bond angles in the realm of 174.0(4)°-179.9(8)°clearly indicate that the three atoms are in a very good linear configuration.…”

Synthesis, crystal structures and magnetic properties of cyanide-bridged macrocyclic complexes

“…Very recently, our group developed trans- [Fe Ⅲ (bpb)(CN) 2 ] − (H 2 bpb = 1,2-bis(pyridine-2-carboxamido)-benzene) as the starting reactant to assemble cyanide-bridged binuclear, trinuclear and one-dimensional complexes [13][14][15] . A series of novel Mn 6 Fe 6 dodecanuclear macrocyclic complexes have been synthesized based on trans- [Fe Ⅲ (bpmb)(CN) 2 ] -(H 2 bpmb = 1,2-bis(pyridine-2-carboxamido)-4-methylbenzene) and Mn(Ⅲ)-Schiff base compounds ([Mn(SB)] + ), one of which has been shown to be a SMM [16,17] .…”