Various Structural Types of Cyanide-Bridged FeIII–MnIII Bimetallic Coordination Polymers (CPs) and Polynuclear Clusters Based-on A New mer-Tricyanoiron(III)Building Block: Synthesis, Crystal Structures, and Magnetic Properties

Abstract

Four cyanide-bridged FeIII–MnIII complexes {[Fe(qxcq)(CN)3][Mn(L1)(H2O)]}[Mn(L1)(H2O)(CH3OH)](ClO4)·1.5MeOH·0.5H2O (L1 = N,N′-bis(3-methoxy-5-bromosalicylideneiminate) (2), {[Fe(qxcq)(CN)3][Mn(L2)]}2·0.5H2O (L2 = N,N′-ethylene-bis(3-ethoxysalicylideneiminate)) (3), [Fe(qxcq)(CN)3][Mn(L3)] (L3 = bis(acetylacetonato)ethylenediimine) (4), [Fe(qxcq)(CN)3][Mn(L4)]·1.5MeOH·0.5CH3CN·0.25H2O (L4 = N,N′-(1,1,2,2-tetramethylethylene)bis(salicylideneiminate)) (5), were prepared by assembling a new structurally characterized mer-tricyanoiron(III) molecular precursor (Ph4P)[Fe(qxcq)(CN)3]·0.5H2O (qxcq− = 8-(2-quinoxaline-2-carboxamido)quinoline anion) (1) and the corresponding manganese(III) Schiff base compound. Complexes 2and 3containa cyanide-bridged heterobimetallic dinuclear entity, which can be further dimerized by self-complementary H-bond interactions through the coordinated water molecule from one complex and the free O4unit from the adjacent complex. Complexes 4 and 5 area one-dimensional coordination polymer (CP) comprised of the repeated [Mn(Schiffbase)-Fe(qxcq)(CN)3] units. Complex 4 shows a linear-chain conformation with two trans-located cyano groups bridgingthe neighboring Mn units, while complex 5 is a zigzag-like 1D CP, where the two cyano groups in cis configurationfunction as bridges. In bothcomplexes 4 and 5, the inter-chain π–πstack interactions within the aromaticrings of cyanide precursor extend the 1D chain into the supermolecular 2D networks. The magnetic property has been experimentally studied and theoretically fitted over the four Fe(III)-Mn(III) complexes, revealing the antiferromagnetic interaction in complexes 2 and 4 and the unusual ferromagnetic coupling in complexes 3 and 5 between the Fe(III) ion and the Mn(III) ion bridged by the cyano group. Furthermore, the different magnetic coupling nature has been analyzed on the basis of the magneto-structure correlation of the mer-tricyanometallate-based Fe(III)-Mn(III) magnetic system.

Cyanide-Bridged Polynuclear and One-Dimensional FeIII-MnIII/II Bimetallic Complexes Based-on Pentacyanoferrite(III) Building Block: Synthesis, Crystal Structures, and Magnetic Properties

“…All the theoretical fitting results are comparable to those found in the previously reported cyanide-bridged Fe III -Mn III/II complexes. [42][43][44]48 The field-dependent magnetizations measured up to 50 kOe at 2 K for complexes 2 and 3 are shown in Figure 6 and the inset of Figure 7, respectively. The field-dependent magnetization curve for complex 2 has a sigmoid shape, implying maybe the metamagnetic behavior: The magnetization first increases slowly with increasing magnetic field until 20 kOe because of the relatively strong intermolecular hydrogen bond interaction, then increases abruptly for a phase transition at about 20 kOe, and finally attains the highest value about 7.45 Nb , which is slightly higher than the saturated value for three Mn(III) ion (S = 2) and one low spin Fe(III) ion (S = 1/2).…”

Syntheses, Structures, and Properties of Mono- and Dinuclear Acetylacetonato Ruthenium(III) Complexes with Chlorido or Thiocyanato Ligands

“…Acetylacetone (Hacac) is well known as one of useful bidentate ligands, which can form chelate complexes, such as [M II (acac) 2 ], [M III (acac) 3 ] and [M III (acac) 2 X 2 ] − , through reactions with various transition metal ions [1-28]. The complexes have been widely investigated, for example, as building blocks for magnetic materials [29][30][31], NMR shift reagents and paramagnetic relaxation reagents [32][33][34][35] and catalysts [36,37]. The trans-[Ru III (acac) 2 (CN) 2 ] − anion has an unpaired electron and has been reported to work as a paramagnetic linker in combination with Mn 2+ and [Fe III salen] + to produce ferri-or ferromagnetic compounds {Mn II [Ru III (acac) 2 (CN) 2 ] 2 } n and [{Fe III (salen)}{Ru III (acac) 2 (CN) 2 }] − with two-and one-dimensional structures, respectively [38,39].…”

Field-Induced Single Molecule Magnetic Behavior of Mononuclear Cobalt(II) Schiff Base Complex Derived from 5-Bromo Vanillin

“…The design of SIMs and SMMs is still a big challenge concerning the fundamental understanding of the origin of magnetic anisotropy and dynamic relaxation. Magnetic anisotropy achieved by strict regulation of geometry is the most critical factor for high-performance SMMs and SIMs [27], which is dependent on axial anisotropy (D), along with spin ground state (S) [28]. Designing the Schiff base ligand-field, which can preserve strict axial symmetry around the metal ion, is one of the best approaches to increase the zero-field splitting in d-metal mononuclear magnets.…”