Hui-Zhong Kou

A dinuclear cyano-bridged complex based on hexacyanoferrate(III) and samarium(III) nitrate : Synthesis and crystal structure

A new complex, [Sm(DMF)4(H2O)4Fe(CN)6]·H2O (DMF = N, N-dimethylformamide), has been synthesized and characterized by X-ray single crystal structure and thermogravimetric analyses. The complex crystallizes in the P21/n space group, with lattice parameters a = 17.583(4) Å, b = 8.870(2) Å, c = 19.845(6) Å, β = 95.98(3)°, V = 3078(1) Å3, Dx = 1.679 Mg m−3, Dm = 1.65(1) Mg m−3, Z = 4. The molecular structure shows that a cyano-bridged bimetallic structure is obtained. The Sm atom is coordinated by eight oxygen atoms of four water molecules and four DMF molecules and one nitrogen atom of the bridging cyanide ligand. The iron atom assumes approximately an octahedral environment surrounded by six CN ligands. The hydrate water molecule is hydrogen-bonded to one of the O atoms bound to Sm. Each terminal CN ligand of the Fe(CN)63− entity is hydrogen-bonded to some O atoms of water molecules. An infrared spectrum is also reported.

Two Ferromagnetic One-Dimensional Nickel(II) Complexes Containing the Diamagnetic [Ni(CN)4]2− Group

A cyano-bridged nickel(II) compound, [NiL][Ni(CN)4]·4H2O (L = 3,10-diethyl-1,3,5,8,10,12-hexaazacyclotetradecane), was prepared and characterized. Single crystal X-ray analysis reveals that the compound assumes a cyano-bridged chain structure in which one nickel(II) ion is coordinated by four cyanide ligands and the other is coordinated by four nitrogen atoms of the macrocyclic ligand and two nitrogen atoms of the bridging cyanide ligands. The six-coordinate nickel(II) centres display an axially elongated octahedron, whereas the four-coordinate nickel(II) centres assume planar geometry. Magnetic investigations on [NiL][Ni(CN)4]·4H2O and a similar chain-like compound [Ni(TIM)][Ni(CN)4] show the presence of weak intrachain ferromagnetic interactions between the paramagnetic nickel(II) ions through the diamagnetic [Ni(CN)4]2− anions.

Synthesis, structure and magnetic properties of a quasi-one-dimensional copper(II) compound. An unusual oxalato-bridged copper dimer

Abstract A new compound [Cu(Him)2(ox)]2[Cu(Him)2(H2O)]2 (Him=imidazole, ox=dianion of oxalic acid) has been prepared and structurally determined. The structure consists of quasi-one-dimensional chains built from two different neutral [Cu(Him)2(ox)]2 and [Cu(Him)2(H2O)(ox)]2 units linked by hydrogen bonds. Two centrosymmetrically related copper ions in the former unit are five-coordinated by two nitrogen atoms from the imidazole ligands and two oxygen atoms from the oxalate anion occupying the basal plane and the oxygen atom of another chelating oxalate situated at the apical position with a weak contact of 2.837(2) A. The coordination environment of the other two copper ions connected by O–H · · · O hydrogen bonds in the other unit can be described as a distorted square pyramid, with two oxygen atoms of the oxalate ion and two nitrogen atoms from the imidazole ligands in the basal plane and one oxygen atom of the coordinated water molecule in the apical position. The (Him)N–H · · · O(ox) hydrogen bonds connect the adjacent units to give rise to a quasi-one-dimensional structure. The room-temperature ESR study gives a g↑ value of 2.07 and a g∥ value of 2.23. From magnetic susceptibility measurements the compound was found to exhibit a weak antiferromagnetic interaction (J=−2.64 cm−1) between the copper(II) ions through the Cu–O–Cu pathways.

Crystal structure and magnetic behaviour of a two-dimensionalstep-shaped cyano-bridged complex[Cu(dien)]3[Fe(CN)6]2·6H2O (dien = diethylenetriamin)

A bimetallic compound [Cu(dien)] 3 [Fe(CN) 6 ] 2 · 6H 2 O (dien = diethylenetriamine) has been prepared and its crystal structure determined: space group P2 1 /a, a = 14.896(3), b = 14.128(5), c = 20.267(6) A, β = 96.31(3)° and Z = 4. The structure consists of a one-dimensional chain of {[Cu(dien)] 2 [Fe(CN) 6 ]} + cations and binuclear {[Cu(dien)(H 2 O)][Fe(CN) 6 ]} - moieties bridged by one CN - ligand of the [Fe(CN) 6 ] 3- anion. The chains are linked by hydrogen bonds giving rise to a unique step-shaped two-dimensional network. In the crystal all the copper(II) ions have a distorted square-based-pyramidal geometry. From magnetic susceptibility measurements the complex was found to exhibit a weak ferromagnetic interaction between the copper(II) and iron(III) atoms.

Synthesis and Magnetic Properties of the First (μ-End-To-End-Azido)Gadolinium(III) Compound: Gd2(phen)4(N3)6(H2O)

Abstract A new Gd(III)-Gd(III) binuclear complex with the formula Gd2(phen)4−(N3)6(H2O) has been synthesized and characterized, where phen is 1,10-phcnanthroline. It has an extended azido-bridged structure consisting of two gadolinium(III) ions in a distorted square antiprismatic environment. The temperature dependence of the magnetic susceptibility of the title complex has been studied resulting in the exchange integral J = −0.23 cm−1 and g = 1.99. This indicates a weak antiferromagnetic interaction between the metal ions.

Reactions of chromium(III) complexes with ferricyanide. Magnetism of K2[Cr(salen)(H2O)][Fe(CN)6]·H2O and the crystal structure of [trans-Cr(tn)2Cl2]3[Fe(CN)6]·6H2O [salen2− = N,N′-ethylenebis(salicylideneaminato) dianion, tn = 1,3-diaminopropane]

Two CrIII–FeIII complexes, K2[Cr(salen)(H2O)][Fe(CN)6]·H2O (1) and [trans-Cr(tn)2Cl2]3[Fe(CN)6]·6H2O (2), have been prepared. Crystal structure determination shows that complex (2) possesses an ionic salt structure. General physical measurements and magnetic studies indicate that (1) assumes a cyanide-bridged dinuclear structure, and that the CrIII–FeIII magnetic coupling through the cyanide bridge is antiferromagnetic, which can be rationalized by the overlap of magnetic orbitals of the same symmetry.

Synthesis and Magnetism of Binuclear Gd(III), Dy(III) and Nd(III) Complexes with Bromanilate Dianion as Bridging Ligand

Abstract Three new binuclear lanthanide(III) complexes, Ln2(phen)4(BA)(ClO4)4·nH2O (Ln = Nd and Dy, n = 3; Ln = Gd, n = 1; phen = 1,10-phenanthroline; BA2- = bromanilate dianion), have been synthesized and characterized. The variable-temperature magnetic susceptibilities of Gd2(phen)4(BA)(ClO4)4·H2O were measured over the temperature range 4–300 K. The observed susceptibility data were best-fit to those from the theoretical magnetic equation by a least-squares method, giving the following parameters: J = -0.10 cm−1, g = 1.95, R = 7.9×10−3.