Yuan-Zhu Zhang

Reversible Thermally and Photoinduced Electron Transfer in a Cyano‐Bridged {Fe2Co2} Square Complex

Flip to be square: Structural, spectroscopic, magnetic, and photomagnetic studies conclusively demonstrate that a tetranuclear cyanometalate {Fe2Co2} complex undergoes reversible thermally and light-induced changes in optical and magnetic properties. This instability is induced by an intramolecular electron transfer, as oberved in three-dimensional Co/Fe Prussian blue compounds (see picture).

First Fe(II)-based cyano-bridged single molecule magnet [CrIIIFeII2] with a large anisotropy

The first Fe(ii)-based cyanometalate single molecule magnet [Cr(III)Fe(II)(2)] exhibits fully visible, frequency-dependent ac susceptibilities above 2 K.

A Cyano-Bridged CrIIICoII Ferromagnet with a Chiral Nanotubular Structure Constituted of Interlocked Single and Double Helices

We have synthesized an unprecedented 3D cyano-bridged Cr(III)-Co(II) compound that self-assembles into a periodically ordered, homochiral interlocking structure composed of left-handed single helices and right-handed double-helical strands. It displays four-connected 6(4)8(2) chiral networks and exhibits ferromagnetic order below 12 K. The formation of the helical structure results in the creation of helical tubular channels in the crystal.

Linking cyano-bridged ladders by azide to form a layered metamagnetElectronic supplementary information (ESI) available: crystal structure plots, more magnetic data and plots for 1 and 2. See http://www.rsc.org/suppdata/cc/b4/b405167j/

Cyano-bridged corrugated ladder-like chains are connected by mu(1,1)-N(3) (end-on, EO) bridges to form a layered coordination polymer, [Mn(N(3))(CH(3)OH)[Cr(phen)(CN)(4)].CH(3)OH (2), which is the first mixed cyano-azide bridged compound, and shows metamagnetism below 21.8 K, a temperature much higher than that (3.4 K) of the crossed double chain [Cr(phen)(CN)(4)](2) [Mn(H(2)O)(2)].4H(2)O (1) based on the same building block [Cr(phen)(CN)(4)](-).

Structures and magnetism of cyano-bridged grid-like two-dimensional 4f–3d arrays

With the introduction of 4,4′-bipyridine N,N′-dioxide (bpdo) ligands, six novel cyano/bpdo mixed-bridged heterometallic 4f–3d compounds {{Ln(III)(bpdo)(H2O)2M(III)(CN)6}·2H2O}n (Ln = Nd(1), Sm(2), Gd(3), Tb(4) with M = Fe; Ln = Nd(5), Sm(6) with M = Co) have been prepared. X-Ray crystallography revealed that they have the same two-dimensional molecular structures, where each [M(CN)6]3− unit uses four co-planar cyanide groups to connect with four square anti-prism Ln3+ ions and, accordingly, each Ln3+ ion links four [M(CN)6]3− units, giving a corrugated grid-like layer and, simultaneously, the next nearest Ln3+ ions are bridged by bpdo in the diagonal direction. Magnetic studies showed that the Ln3+–Fe3+ interaction is ferromagnetic for NdFe (1), antiferromagnetic for SmFe (2) and GdFe (3), while negligible for TbFe (4). Especially, 2 and 3 exhibited ferrimagnetic orderings below 2.9 and 1.9 K, respectively, with a coercive field of 40 Oe at 1.8 K for 2. Additionally, 5 showed an unusual field-induced magnetization relaxation.

A cyano-based octanuclear {Fe(III)(4)Ni(II)(4)} single-molecule magnet.

A new low symmetry octanuclear cyano-based {Fe(III)(4)Ni(II)(4)} single-molecule magnet (SMM) is described. This SMM exhibits the highest energy barrier (Delta/k(B) approximately 33 K) for magnetization reversal seen for any first-row cyanide-based complex. The importance of anisotropy axes alignment and their impact on SMM properties are illustrated when cubic {Fe(III)(4)Ni(II)(4)} boxes are compared to octanuclear complexes of lower overall symmetry.

Pyrazolylborates and Their Importance in Tuning Single-Molecule Magnet Properties of {FeIII2NiII} Complexes

A new tricyanoferrate(III) building block and a trinuclear single-molecule magnet derivative are described. The treatment of a 2:1 ratio of [NEt(4)][(Tp*(Bn))Fe(III)(CN)(3)]·H(2)O·MeOH [1; Tp*(Bn) = tris(3,5-dimethyl-4-benzyl)pyrazolylborate] with nickel(II) trifluoromethanesulfonate gives {[(Tp*(Bn))Fe(III)(CN)(3)](2)[Ni(II)(DMF)(4)]}·2DMF (2; DMF = N,N-dimethylformamide). The symmetry-equivalent Fe(III)(LS) ions lead to a favorable alignment of anisotropy tensors (i.e., Fe···B axes) in 2, and an energy barrier of Δ(eff)/k(B) = 16.7 K is found for the S(T) = 2 complex.

Two-dimensional rare earth coordination polymers involving different coordination modes of thiodiglycolic acid

Two coordination polymers ½La2ðtdgaÞ3ðH2OÞ2� n (1) and f½Pr2ðtdgaÞ3ðH2OÞ2 �� H2Ogn (2) were obtained by the reaction between LnðOHÞ3 (Ln ¼ La, Pr) and thiodiglycolic acid ðH2tdga ¼ H2SðCH2CO2Þ2Þ, which have a novel double-layered and a single-layered structure, respectively. In the complexes, new coordination modes of the ligand were observed. 2002 Elsevier Science B.V. All rights reserved.

Synthesis and Characterization of Di- and Trivalent Pyrazolylborate β-Diketonates and Cyanometalates

The syntheses, structures, and magnetic properties of a series of di- and trivalent hydridotris(3,5-dimethylpyrazol-1-yl)borate (Tp*) cyanomanganates are described. Treatment of tris(acetylacetonate)manganese(III) [Mn(acac)(3)] with KTp* and tetra(ethyl)ammonium cyanide affords [NEt(4)][(Tp*)Mn(II)(κ(2)-acac)(CN)] (1), as the first monocyanomanganate(II) complex; attempted oxidation of 1 with iodine affords {(Tp*)Mn(II)(κ(2)-acac(3-CN))}(n) (2) as a one-dimensional chain and bimetallic {[NEt(4)][(Tp*)Mn(II)(κ(2)-acac(3-CN))](2)(μ-CN) (3) as the major and minor products, respectively. A fourth complex, [NEt(4)][(Tp*)Mn(II)(η(2)-acac(3-CN))(η(1)-NC-acac)] (4), is obtained via treatment of Mn(acac(3-CN))(3) with KTp* and [NEt(4)]CN, while [NEt(4)](2)[Mn(II)(CN)(4)] (5) was prepared from manganese(II) trifluoromethanesulfonate and excess [NEt(4)]CN. Tricyanomanganate(III) complexes, [cat][(Tp*)Mn(III)(CN)(3)] [cat = NEt(4)(+), 7; PPN(+), 8], are prepared via sequential treatment of Mn(acac(3-CN))(3) with KTp*, followed by [NEt(4)]CN, or [cat](3)[Mn(III)(CN)(6)] with (Tp*)SnBu(2)Cl. Magnetic measurements indicate that 1, 2, and 4 contain isotropic Mn(II) (S = (5)/(2); g = 2.00) centers, and no long-range magnetic ordering is found above 1.8 K. Compounds 7 and 8 contain S = 1 Mn(III) centers that adopt singly degenerate spin ground states without orbital contributions to their magnetic moments.