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Three Eu3+ complexes containing a neutral tripodal ligand possessing a predictable coordination mode have been obtained and studied. The trispyrazolylmethane complexes have an aqua ligand in the coordination sphere, forming both the mononuclear species [Eu(HCPz3)H2O(NO3)3] and the dimer [Eu(HCPz3)H2O(CF3SO3)3]2, having a Chinese lantern structure, whereas the use of the methylated tripod leads to the water-free complex, [Eu(HC(PzMe2)3)(NO3)3]. A qualitative analysis of the magnetic susceptibility of polycrystalline samples demonstrated that the magnetic properties can be described using a simple Van Vleck formula with spin–orbit coupling parameter (λ = 383 ÷ 406 cm−1) close to the values for free Eu3+ ions. The stereochemical analysis of the coordination environment of [Ln(HC(PzMe2)3)(NO3)3] has shown that these complexes can be used as diamagnetic model systems to obtain information on the crystal field effects in the paramagnetic monoradical complexes, [LnRad(NO3)3], since both types of compounds have the same type of coordination polyhedron (symmetry point group D3h) and very close Ln–donor atom distances. [ABSTRACT FROM AUTHOR]

A predictable type of coordination is a key property of tripodal ligands. Homo- and heteroleptic lanthanide complexes with tripodal ligands are a representative class of compounds. However, despite the fact that many of them are paramagnetic, their magnetic behavior is poorly studied. This is because their photophysical and catalytic properties are considered more attractive. In the present review, we try to summarize the available structural information and only a few examples of data on magnetic properties in order to draw some conclusions about the prospect of such ligands in the design of quantum molecular magnets involving lanthanide (Ln) ions. We would also like to catch the reader's attention to the fact that, despite the consideration of a large part of the currently known Ln compounds with tripodal ligands, this review is not exhaustive. However, our goal is to draw the attention of magnetochemists and theoreticians to a whole niche of air-stable Ln complexes that is still out of their field of vision. [ABSTRACT FROM AUTHOR]

Two novel 1D heterobimetallic compounds {[MnIII(SB2+)MIII(CN)6]·4H2O}n (SB2+ = N,N′-ethylenebis(5-trimethylammoniomethylsalicylideneiminate) based on orbitally degenerate cyanidometallates [OsIII(CN)6]3− (1) and [RuIII(CN)6]3− (2) and MnIII Schiff base complex were synthesized and characterized structurally and magnetically. Their crystal structures consist of electrically neutral, well-isolated chains composed of alternating [MIII(CN)6]3− anions and square planar [MnIII(SB2+)]3+ cations bridged by cyanide groups. These -ion magnetic anisotropy of MnIII centers. These results indicate that the presence of compounds exhibit single-chain magnet (SCM) behavior with the energy barriers of Δτ1/kB = 73 K, Δτ2/kB = 41.5 K (1) and Δτ1/kB = 51 K, Δτ2 = 27 K (2). Blocking temperatures of TB = 2.8, 2.1 K and magnetic hysteresis with coercive fields (at 1.8 K) of 8000, 1600 Oe were found for 1 and 2, respectively. Theoretical analysis of the magnetic data reveals that their single-chain magnet behavior is a product of a complicated interplay of extremely anisotropic triaxial exchange interactions in MIII(4d/5d)–CN–MnIII fragments: −JxSMxSMnx−JySMySMny−JzSMzSMnz, with opposite sign of exchange parameters Jx = −22, Jy = +28, Jz = −26 cm−1 and Jx = −18, Jy = +20, Jz = −18 cm−1 in 1 and 2, respectively) and single orbitally degenerate [OsIII(CN)6]3− and [RuIII(CN)6]3− spin units with unquenched orbital angular momentum in the chain compounds 1 and 2 leads to a peculiar regime of slow magnetic relaxation, which is beyond the scope of the conventional Glaubers's 1D Ising model and anisotropic Heisenberg model. [ABSTRACT FROM AUTHOR]

This review is devoted to an analysis of currently known heterometallic molecular magnets based on an orbitally degenerate 5d metalloligand, [ReIV(CN)7]3−. Heptacyanidometallates with a pentagonal bipyramidal structure of the coordination site and degenerate ground spin state are the source of anisotropic magnetic exchange interactions upon the formation of cyanide-bonded assemblies involving the paramagnetic complexes of the first transition series. Therefore, the development of methods for chemical design using such molecular magnetic modules is extremely important. If for the 4d congener, isoelectronic [MoIII(CN)7]3−, a family of approximately 40 heterometallic compounds, was obtained, whereas for heptacyanorhenate(IV), no more than 20 are known. However, as a result of recent studies, heterobimetallic magnetic assemblies of all dimensionalities have been synthesized, from 0D to 1D, demonstrating slow magnetization relaxation, to 2D networks and 3D frameworks possessing large magnetic hysteresis. The most anisotropic is a 2D network, PPN[{MnIII(acacen)}2ReIV(CN)7]·Solv, with a critical temperature of 20 K and magnetic hysteresis with a record coercivity for cyanide-bridged molecular materials. [ABSTRACT FROM AUTHOR]

The first neutral 2D heterometallic assemblies based on orbitally degenerate heptacyanidorhenate(IV) were prepared and structurally characterized. An analysis of the magnetic data for the polycrystalline samples of Ph4P[{Mn(acacen)}2Re(CN)7]·Solv (1) and PPN[{Mn(acacen)}2Re(CN)7]·Solv (2) have shown that both materials display slow magnetic relaxation at temperatures below 10 and 21 K for 1 and 2, respectively. Despite the presence of the same molecular magnetic modules that make up the anionic layers, the studied 2D networks differ significantly in magnetic anisotropy, having a small coercive field (0.115 T) for 1 and a large one (~2.5 T) for 2 at 2 K. In addition, for both polymers a M(H) value does not saturate at the maximum available field of 7 T, and the material 2 is a metamagnet. This intriguing difference originates from the cooperative anisotropic spin interaction in ReIV−CN−MnIII pairs and the zero field splitting (ZFS) effect of MnIII ions with a noncollinear alignment of the local magnetic axes in crystals of the compounds. [ABSTRACT FROM AUTHOR]

The first neutral 0D and 1D heterometallic assemblies based on orbitally degenerate heptacyanidorhenate(IV) were prepared and structurally characterized. An analysis of the magnetic data of polycrystalline samples showed that both compounds display slow magnetization relaxation at temperatures below 5 K. The very low temperature measurements of the magnetization on the single crystals demonstrate that for the 1D compound {[Mn(SB2+)Re(CN)7]·7H2O}n (1) and the 0D complex [Mn(SB2+)(H2O)Re(CN)7]·2H2O (2), the hysteresis loops open just below 2.2 and 1.8 K, respectively. Thus, heterometallic polymer 1 is the first single-chain magnet involving a pentagonal bipyramidal [ReIV(CN)7]3− synthon, and the binuclear complex 2 represents a single-molecule magnet. [ABSTRACT FROM AUTHOR]

A pioneering research on a self-assembly of the magneto-anisotropic module [Re(CN)7]3- with the Mn(III) complexes involving Salen type (N,N'-ethylenebis(salicylideneiminate)) Schiff base (SB) ligands was performed using the known [Mn(3MeOSalen)(H2O)2]2(ClO4)2.H2O (1) and the firstly synthesized [Mn2(5MeSalen)2OAc]PF6 (2). In the case of 1, a slow diffusion of the component solutions led to the ionic compound Ph4P[Mn(3MeOSalen)(H2O)2]2[Re(CN)7].6H2O (3). The direct mixing of the same solutions has resulted in the microcrystalline nearly insoluble solid [Mn(3MeOSalen)(H2O))4Re(CN)7]ClO4.1.5MeCN.6.5H2O, which is likely to comprise the pentanuclear clusters [(MnIII(SB)(H2O))4Re(CN)7]+. The use of 2 resulted in a 2D-network assembly of octanuclear clusters, [{(Mn(5MeSalen))6(H2O)2Re(CN)7}2Re(CN)7]Cl2(PF6).H2O (4), incorporating one Re-center in a pentagonal bipyramid coordination environment, while another has strongly distorted capped trigonal prism as a coordination polyhedron. The latter was observed for the first time for Re(IV) complexes. A synthetic challenge to obtain the 0D assemblies with Re:Mn ≥ 3 has yielded a hexanuclear complex [Mn(5MeSalen)H2O(i-PrOH)] [(Mn(5MeSalen))5H2O(i-PrOH)2Re(CN)7](PF6)2(OAc).2i-PrOH (5) being 1D chain via a bridging phenoxyl group. Owing to a low solubility of the final product, an addition of a bulk anion Ph4B- to the MeCN/MeOH solution of [Re(CN)7]3-and 1 in ratio 1:6 resulted in rhenium-free matter [Mn(3MeOSalen)(H2O)2][Mn(3MeOSalen)(H2O)MeCN](Ph4B)2.5MeCN (6). [ABSTRACT FROM AUTHOR]

The article presents a study which discusses synthesis and crystallographical evidence of pentagonal bipyramidal polyhedron of Heptacyanoosmate (IV) and mentions role of cyanide ligand in coordination chemistry.

The ligand exchange in (n-Bu4N)2OsIVCl6 (n-Bu4N = tetra-n-butylammonium) leads to the formation of the osmium(IV) heptacyanide, the first fully inorganic homoleptic complex of heptacoordinated osmium. The single-crystal X-ray diffraction (SC-XRD) study reveals the pentagonal bipyramidal molecular structure of the [Os(CN)7]3- anion. The latter being a diamagnetic analogue of the highly anisotropic paramagnetic synthon, [ReIV(CN)7]3- can be used for the synthesis of the model heterometallic coordination compounds for the detailed study and simulation of the magnetic properties of the low-dimensional molecular nanomagnets involving 5d metal heptacyanides. [ABSTRACT FROM AUTHOR]

Upon the interaction of the hydrated lanthanide(III) salts found in acetonitrile solution with a tripodal paramagnetic compound, 4,4-dimethyl-2,2-bis(pyridin-2-yl)-1,3-oxazolidine-3-oxyl (Rad), functionalized by two pyridyl groups, three neutral, structurally characterized complexes with diamagnetic polydentate ligands—[Dy(RadH)(hbpm)Cl2], [Yb2(ipapm)2(NO3)4], and [Ce2(ipapm)2(NO3)4(EtOAc)2]—were obtained. These coordination compounds are minor uncolored crystalline products, which were formed in a reaction mixture due to the Rad transformation in a lanthanide coordination sphere, wherein the processes of its simultaneous disproportionation, hydrolysis, and condensation proceed differently than in the absence of Ln ions. The latter fact was confirmed by the formation of the structurally characterized product of the oxazolidine nitroxide transformation during its crystallization in toluene solution. Such a conversion in the presence of 4f elements ions is unique since no similar phenomenon was observed during the synthesis of the 3d-metal complexes with Rad. [ABSTRACT FROM AUTHOR]

Two diradical complexes of the formula [LnRad2(CF3SO3)3] c (Ln(III) = Dy, Eu, Rad = 4,4-dimethyl-2,2-bis(pyridin-2-yl)-1,3-oxazolidine-3-oxyl) were obtained in air conditions. These are the first examples of diradical compounds of lanthanides and oxazolidine nitroxide. The complexes were characterized crystallographically and magnetically. Single crystal XRD analysis revealed that their coordination sphere is composed of three monodentate triflates and two tripodal Rad, which coordinate the central atom in a tridentate manner via two N atoms of the pyridine groups and the O atom of a nitroxide group. The LnO5N4 polyhedron represents a spherical capped square antiprism with point symmetry close to C4v. The data of static magnetic measurements are compatible with the presence of two paramagnetic ligands in the coordination sphere of the metal. [ABSTRACT FROM AUTHOR]