Syntheses, Structures, and Magnetic Properties of Three Manganese(II)-Octacyanotungstate(V) Bimetallic Compounds with Linear Ligands

Abstract

Three manganese(II)-octacyanotungstate(V) bimetallic compounds, [Mn(H 2 O) 2 (dpe)] 3 [W(CN) 8 ] 2 ·2dpe·7H 2 O (dpe = trans-1,2-di(4-pyridyl)ethene) (1), [Mn(H 2 O) 2 (azpy)] 3 [W(CN) 8 ] 2 ·3azpy·4H 2 O (azpy = 4,4′-azopyridine) (2), and [Mn(H 2 O) 3 (azpy)] 2 [Mn(CH 3 CN) 2 (azpy)][W-(CN) 8 ] 2 ·5azpy·2H 2 O (3) were prepared by in situ or secondary assembly methods. Compounds 1 and 2 show three-dimensional (3D) networks through the cross-link of one-dimensional (1D) infinite 3,2-chains or ropeladder chains with linear ligands (dpe, azpy), while compound 3 adopts a 1D ribbon-like structure by the connection of pentanuclear repeating units with azpy linkers. Magnetic studies reveal that compounds 1−3 show intramolecular antiferromagnetic coupling between Mn(II) and W(V) centers, which produce the typical ferrimagnetic chain behaviors for compounds 1 and 2 but paramagnetic properties for compound 3. Notably, field-induced metamagnetic behavior was detected for compound 2, indicating it undergoes a transition from the antiferromagnetic ground state to ferrimagnetic phase above critical dc field. ■ INTRODUCTIONIn the past few years, the design and synthesis of coordination compounds have attracted much attention because of their intriguing topologies and fascinating potential applications. 1 Especially, considerable efforts into crystal engineering have been devoted to the design and construction of octacyanometallates [M(CN) 8 ] 3−/4− (M = Mo, W, and Nb)-based magnets. 2,3 Octacyanometallates as versatile building blocks not only can mediate strong coupling interactions between metal centers but also adopt three different spatial configurations depending on the external environment (square antiprism, dodecahedron, and bicapped trigonal prism). The combination of [M(CN) 8 ] units as carriers of unpaired spin with 3d metal ions has produced various dimensional molecular structures ranging from zero-dimensional (0D) clusters to three-dimensional (3D) networks, and the resulting materials displayed rich magnetic properties such as high T c values, 4−6 photo-/guest-induced magnetism, 7−10 single molecule or single chain magnets, 11,12 and spin crossover magnetism. 13,14 From the synthesis point of view, the chelated ligands have been usually used to control the coordination number and spatial arrangement around metal centers for cyanide-bridging, thus resulting in low-dimensional octacyanometallate-based structures rather than extended frameworks, while longer bridging ligands (e.g., polypyridines, pyridyl N-oxides) were used to construct high-dimensional structures. 2 Notably, spacer ligands have been applied in the construction of extended networks from preorganized Mn 9 W 6 clusters; for example, {Mn 9 W 6 } clusters could be connected by 4,4′-bipyridine (4,4′-bpy) and trans-1,2-di(4-pyridyl)ethene (dpe) linkers into 2D and 3D hybrid networks, respectively. 15,16 Meanwhile, {Co 9 W 6 } clusters were combined with 4,4′-bipyridine-N,N′-dioxide (4,4′-bpdo) linkers, forming H-bonded supramolecular chains and 1D nanowir...

The Temperature Effect on the Structural Features of Bidentate Ligand‐Decorated Cyanide‐Bridged MnII‐MoV Compounds

“…The equatorial plane and apical sites are all occupied by water molecules with Mn–O distances of 2.100–2.391 Å. The coordinated arrangement and parameters of Mn2 were relatively common in the M V/IV (CN) 8 ‐Mn II compounds , . Subsequently, the central Mo1 and Mn1 atoms are linked alternatively by CN groups, generating a 2D waved grid‐like layer (Figure b, Figure c), as found in (tetrenH 2 ) 0.5 [Mn II (H 2 O) 2 ][Mo V (CN) 8 ] · 2H 2 O and {(tetrenH 5 ) 0.8 Cu II 4 [W V (CN) 8 ] 4 · 7.2H2O} n .…”

Magnetism in Heterobimetallic and Heterotrimetallic Chains Based on the Use of [WV(bipy)(CN)6]– as a Metalloligand

“…Previous magneto‐structural investigations on the single cyanido‐bridged Mn II ‐octacyanotungstate(V) pathway revealed the occurrence of antiferromagnetic interactions up to –39 cm –1 ,, , the spin Hamiltonian being defined as H = – J S W S Mn . It was found that the magnetic coupling in this system depends on the structural parameters such as the type of coordination polyhedron of the [W(CN) 8 ] 3– metalloligand and parameters within the cyanide‐bridged linkage (Mn–N bond length, Mn–N–C bond angle and Mn ··· W separation) .…”

“…Classic examples are the systems containing Cu II and Mn II bridged by oxamato or oxamido ligands , . Since the first report on a ferrimagnetic chain in the early '80s by Verdaguer, the ferrimagnetic strategy was applied and developed for other examples of bimetallic monodimensional complexes , . Examples of d–d and d–f ferrimagnetic heterobimetallic chains based on cyanido metalloligands are still limited.…”

“…Examples of d–d and d–f ferrimagnetic heterobimetallic chains based on cyanido metalloligands are still limited. Several examples of ferrimagnetic chains are the 3d–3d′ systems {Mn III (salcy)Cr III (Tp)(CN) 3 } n , {[Fe III (bpca)(µ‐CN) 3 Mn II (H 2 O) 3 ][Fe III (bpca)(CN) 3 ]}, {[Fe III (pzcq)(CN) 3 ][Mn III (salen)]}, [Mn III (salhd)(µ‐CN)Fe III /Cr III (CN) 3 (bpym)(H 2 O) 2 ] n and {[Fe III (dmbpy)(CN) 4 ] 2 Mn II (H 2 O) 2 } n , the 3d–4/5d compounds {[Mn II 2 (tptz) 2 (MeOH) 3 W V (CN) 8 ][Mn II (tptz)(MeOH)W V (CN) 8 ]}, {[Mn II 2 (tptz) 2 (MeOH) 3 (OAc)][W V (CN) 8 ]}, {[Mn II 2 (H 2 O) 2 (CH 3 COO)][Mo V (CN) 8 ] · 2H 2 O} n , {[Mn II (H 2 O) 2 (dpe/azpy)] 3 [W V (CN) 8 ] 2 }, [Mn III (5‐Cl/Brsalen)(H 2 O)(MeOH)] {[Mn III (5‐Cl/Brsalen)(H 2 O)][Mn III (5‐Cl/Brsalen)Mo V (CN) 8 ]} and {[Mn III (L2)][W V (CN) 6 (bpy)]} and the 3d–4f complexes {Gd III (pzam) 3 (H 2 O)M V (CN) 8 } · H 2 O (M = Mo, W), {Gd III (DMA) 5/6 [W V (CN) 8 ]} [ R , R ‐salcy and S , S ‐salcy = N , N′ ‐(1,2‐cyclohexanediylethylene)bis(salicylideneiminate) dianion, pzcq = 8‐(pyrazine‐2‐carboxamido)quinolone anion, H 2 salhd = 1,2‐bis(salicylidenimine)cyclohexane, tptz = 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine, dpe = trans ‐1,2‐di(4‐pyridyl)ethene, azpy = 4,4′‐azopyridine, 5‐Cl/Brsalen = N , N′ ‐ethylenebis(5‐chloro/bromosalicylideneiminato) dianion, H 2 L2 = N , N′ ‐bis(2‐hydroxynaphthalene‐1‐carbaldehydene)‐ trans ‐diaminocyclohexane, pzam = pyrazine‐2‐carboxamide and DMA = dimethylacetamide].…”

Mixed-Ligand Architected Unique Topological Heterometallic Sodium/Cobalt-Based Metal–Organic Framework for High-Performance Supercapacitors

“…In light of the above challenges, herein, we have synthesized a new heterometallic Na/Co-based MOF ( 1 ), [Na 2 Co­(SDCA)­( μ 2 -OH) 2 ( μ 2 -H 2 O) 2 (Azopy)] n , by a facile mixed ligand strategy using 2,5′-thiophenedicarboxylic acid (H 2 SDCA) and 4,4′-azopyridine (Azopy) by slow-diffusion technique at room temperature. It is well-known that multicarboxylate linkers are repeatedly preferred due to their multi coordination manners through the complete/partial deprotonation of −COOH groups in the construction of MOFs. − Here, SDCA is chosen due to its multicoordination ability with metal center through the −COO – group to deliver unique structure with fascinating properties and also its derivatives are widely employed as electrode materials , while the auxiliary pillared Azopy linkers embody the 4-pyridyl building elements, are usually employed as pillars for the extension of frameworks with good flexibility/stability, and the presence of delocalized π-electrons in the pyridyl rings are also accomplished to encourage the electrical conductivity in the resulting MOFs. − Therefore, 1 was expected to give a synergistically enhanced supercapacitor performance with excellent cycling stability, which is also a central idea of the present work.…”