Azido-Cyanide Mixed-Bridged Fe^III–Ni^II Complexes

Abstract

The successful introduction of azide ions as secondary bridges into the FeIII–NiII cyanide system afforded two clusters and one unique 4(3),2-ribbon chain: [(bpzpy)2Ni2(μ2-1,1-N3)2{(pzTp)­Fe­(CN)3}2]·3H2O [1; bpzpy = 2,6-bis­(pyrazol-1-yl)­pyridine, and pzTp = tetrakis­(pyrazolyl)­borate], [(L1)2Ni4(μ3-1,1,1-OCH3)2(μ2-1,1-N3)2(H2O)2{(Tp)­Fe­(CN)3}2]·2CH3OH·H2O [2; Tp = hydrotris­(pyrazolyl)­borate, and HL1 = 2,6-bis­{(2-hydroxypropylimino)­methyl}-4-methylphenol], and [(L2)2Ni3(μ2-1,1-N3)4{(pzTp)­Fe­(CN)3}2] n (3; L2 = 2-{[phenyl­(pyridin-2-yl)­methylene]­amino}­ethan-1-amine). Both 1 and 2 feature the centrosymmetric {FeIII–NiII 2–FeIII} and {FeIII–NiII 4–FeIII} rodlike structures in which the two peripheral [(TpR)­Fe­(CN)3]− anions act as monodentate ligands via one cyanide group to link the central azide-bridged [Ni2] and [Ni4] subunit, respectively, while 3 displays an extended structure of the double-zigzag (4,2-ribbon) chain in which the double end-on azide-bridged trinuclear [Ni3] subunits serve as the 4-connected nodes. Magnetic study revealed that intramolecular ferromagnetic coupling is dominated by the azide or cyanide bridges in all of the complexes. Remarkably, complex 1 behaves as a single-molecule magnet with an effective energy barrier of 16.5 cm–1 at zero dc field, while complex 3 exhibits metamagnetism with a hidden spin canting property below 12 K.

Light actuated single-chain magnet with magnetic coercivity

“…The bridging cyanide bands shifted to the position with higher wavenumbers as compared with the free cyanide stretching modes, which can be observed in other cyanide-bridged transition metal complexes. 69 Therefore, the two absorption bands can be attributed to the bridging cyanide stretching of the {Fe III LS (μ-CN)Co II HS } unit and the terminal cyanide stretching of the [( Pz Tp)Fe III (CN) 3 ] − unit. When cooling the sample, three new bands appeared.…”

“…The bridging cyanide bands shifted to the position with higher wavenumbers as compared with the free cyanide stretching modes, which can be observed in other cyanidebridged transition metal complexes. 69 The temperature-dependent susceptibilities of 1 and 2 were collected under a DC field of 1000 Oe. As shown in Fig.…”

Thermo- and photo-induced electron transfer in a series of [Fe2Co2] capsules

“…To avoid overparameterization, g Fe is fixed as 2.6 based on the previous related literature. 35 Given the significant π–π stackings, zj ′ corresponding to the intermolecular interactions has also been included, the best fitting gave the values listed in Table 3.…”

“…To avoid overparameterization, g Fe is fixed as 2.6 based on the previous related literature. 35 Given the significant π-π stackings, zj′ corresponding to the intermolecular interactions has also been included, the best fitting gave the values listed in Table 3. The zfs fitting parameters for 1-3 are comparable to those reported for high-spin Co(II) in a distorted octahedral coordination environment.…”

Polyoxometalate-Assisted Assembly of Pearl-Chain-Like Cyanide-Bridged Single-Chain Magnets

“…Most recently, our group succeeded in incorporating some selected azido-bridged Ni­(II) clusters into such a cyanide system, with one exhibiting a novel 4,2-ribbon chain. However, this compound did not show SCM behavior despite the fact that all of the B···Fe vectors are parallel, likely due to the counteracting effect between the anisotropic Fe­(III) and Ni­(II) ions …”