Liao Daizheng

Synthesis and X-ray crystal structure of μ-terephthalato nickel(II) binuclear complex [Ni2(TPHA)(bpy)4](ClO4)2

Abstract The X-ray crystal structure of the complex [Ni2(TPHA)(bpy)4](ClO4)2 (TPHA = terephthalato, bpy = 2,2′-bipyridine) has been determined. Its structure consists of a terephthalato bridged nickel(II) binuclear cation and non-coordinated perchlorate anions. In the complex the TPHA bridges are in a bis bidentate configuration. The environment of the nickel(II) ion is distorted octahedral.

Crystal structure and magnetic properties of binuclear copper(II) complexes of 2,6-diformyl-4-tert-butylphenol di(benzoylhydrazone)

Abstract The crystal structure and magnetic properties of copper(II) binuclear complexes are reported. The binucleating ligand (L) is 2,6-diformyl-4-tert-butylphenol di(benzoyl-hydrazone). The small exogenous bridging anions are OR− and Br− for complexes 1 and 2, respectively. The magnetic coupling parameters are consistent with antiferromagnetic exchange between the two copper(II) centres and fits of the data with binuclear magnetic exchange models give antiferromagnetic coupling parameters of 2J = −309 and −47.8 cm−1 for complexes 1 and 2, respectively. Crystal data for complex 1 [Cu2L(C2H5O) (CH3OH)](ClO4)2, Mr = 844.59 g mol−1, space group P 1 , a = 10.552(1), b = 13.271(2), c = 14.4184(4) A, α = 72.53(1), β = 78.46(2), γ = 72.83(1)°, V = 1826.2 A3, Z = 2, Dx = 1.534 g cm−3 λ(Mo-Kα) = 0.71037 A, μ = 13.78 cm−1, F(000) = 864, R = 5.2%, Rw = 6.3% with 1992 observed unique reflections.

Synthesis and crystal structure of a binuclear zinc(II) complex of 2,6-diformylpyridine N--oxide bis(benzoylhydrazone)

Abstract The binuclear zinc(II) complex [Zn 2 L(O 2 CCH 3 ) 2 ] · CH 3 CCH 2 OOH was synthesized by a template reaction in alcohol. The crystal and molecular structure of this complex has been determined by X-ray analysis. The binucleating ligand L, 2,6-diformylpyridine TV-oxide bis(benzoylhydrazone), is in doubly deprotonated form. All the coordinated atoms in the bis-Schiff base ligand and two zinc atoms in the complex molecule are coplanar, and the N -oxide oxygen atom bridges two zinc atoms with the same bond length of 2.24(1) A. The two acetate ions act as bidentate ligands linking two zinc atoms, both being in a distorted trigonal-bipyramidal environment.

SYNTHESIS, CRYSTAL STRUCTURE AND MAGNETIC PROPERTIES OF DIBROMO(1,13-DIOXA-4,7,10,16,19,22-HEXAAZACYCLOTETRACOSANE)DICOPPER(II) BROMIDE

Abstract A new dinuclear copper(II) complex with the macrocyclic ligand (1,13-dioxa-4,7,10,16,19,22-hexaazacyclotetracosane), [24]-N6O2, has been prepared and its crystal structure has been determined. The two copper ions are contained inside the molecular cavity and are bound to the NNN chelating subunits situated at the two poles of the macrocycles. Each copper(II) centre displays square-pyramidal coordination. The CuIICuII distance is 5.16 A, and the macrocycle has an S-type conformation. The molecule has a symmetry centre. The temperature dependence of the magnetic susceptibility for the title complex was studied in the range 4-300 K, giving an exchange integral of J = 19.1 cm−1. This indicates a ferromagnetic interaction between the metal ions. The ESR spectra are also discussed.

Crystal structure and ferromagnetic behavior of a μ-acetato-bridged one-dimensional linear-chain copper(II) complex

Abstract A μ-acetato-bridged copper(II) complex, CuBr(CH 3 COO)·2H 2 O, was synthesized and its structure refined by X-ray single crystal structure analysis to R = 0.071. The crystals are orthorhombic, of space group Pnma , with cell constants a = 8.980(2), b = 7.569(2), c = 10.393(3) A , and Z = 4 . The copper(II) ions are bridged by acetate ions to form a one-dimensional linear-chain structure. Magnetic measurements in the range 4–250 K and subsequent calculations based upon Bakers equation suggest intrachain ferromagnetic coupling between the copper(II) ions with J = 3.8 cm −1 .

Synthesis, structure, magnetic properties and molecular mechanics study on the dinuclear copper (II) with biradical

Dinuclear copper complex with biradicals [Cu(hfac)2]2PhBNM(PhBNM = 2,5-bimethyl-1,4-bis (4,4,5,5-tetramethyllimidazoline-1-oxyl-3-oxide)phenyl,hfac=hexafluoroacetylacetonate) has been synthesized and characterized. It crystallized in the monoclinic system, with space groupC2/c,a=1.9012(4),b=1.3718(3),c=2.1620(4) nm, s=97.55(3)°,Z=4. The X-ray structure analysis shows that the molecular structure consists of two kinds of conformations. The ratio of them is 7:3. The energy of two conformations, calculated with molecular mechanics, are different,E1=740 kJ/mol, andE2=771 kJ · mol−1. The CNDO/k results on the complex indicate that the orbital energy of low spin state is lower than that of high spin state, which correspond with the results of magnetic measurement.

Progress in magnetic couple system of nitroxidemetal complexes

Metal-radical method is an effective approach to synthesizing magnetic molecular materials. With the development in decades, the study of nitroxide-metal complexes has made great progress in model, theoretical treatment and design of molecules. Several mechanisms of the metal-radical magnetic coupling are discussed. Molecular magnetic project of nitroxide-metal mmplutes has made fruitful achievements, but crystal magnetic project is difficult to be controlled, and it is a challenge to chemists. The studies on nitronyl nitroxide-metal complexes are summarized. At present, there are three major approaches to increasing theTc of the metal-radical compounds: (i) Searching for nitronyl nitroxide ligands that can yield 3-D ferroor femmagnetic structures; (II) decorating the structure of radicals with the aim to enhance the coordinate capability of radicals; (III) grafting polynitmxide radicals as a versatile bridge. The third approach, namely searching for polynitroxide ligand, will serve as a hopeful strategy for exploring higherTc radical molecule-based magnets.

Novel dioximato-bridged chromium(III)-copper(II)-chromium(III) trinuclear complexes with ferromagnetic exchange interactions

SummaryTwo new dioximato-bridged trinuclear CrII-CuII-CrIII complexes, [Cr(salen)-Cu(α-BD)2-Cr(salen)] (1) and [Cr(salen)-Cu(α-FD)2-Cr(salen)]-H2O (2), have been prepared and characterized [salen2− = N,N′-ethylene-bis (salicylideneiminate), (α-BD)2− = α-benzyldioximato and (α-FD)2− = α-furildioximato]. Magnetic susceptibility measurements in the 4.2–300 K range demonstrated the operation of a ferromagnetic interaction between the adjacent CrIII and CuII ions through oximato bridges in both (1) and (2). Based on spin Hamiltonians Ĥ=−2J(Ŝ1Ŝ2+Ŝ2Ŝ3)(S1=S3=3/2,S2=1/2) the exchange integrals (J) were evaluated as 3.19 and 5.38 cm−1 for (1) and (2), respectively.

Synthesis and magnetic properties of binuclear copper(II) complexes with alkoxide bridges

Abstract Five binuclear Cu II complexes [Cu 2 L(μ-N 3 )](ClO 4 ) 2 · 1 2 C 2 H 5 OH · 2H 2 O ( 1 ), [Cu 2 L(μ-C 7 H 5 O) 2 ](ClO 4 ) 2 ( 2 ), [Cu 2 L(μ-C 3 N 2 H) 3 ](ClO 4 ) 2 · 3 2 C 2 H 5 OH ( 3 , [Cu 2 L(μ-Br)]Br 2 · H 2 O ( 4 ), [Cu 2 L(μ-OH)](ClO 4 ) 2 · 3H 2 O ( 5 ) were synthesized (where HL are 1:2 Schiff bases derived from 1,3-diamino-2-hydroxypropane and picolinaldehyde N -oxide). Based on the IR spectra, elemental analyses and conductivity measurements, these complexes are proposed to have an endogenous bridge (alkoxide) and an exogenous bridge (it may be an anion). The complexes were characterized by variable temperature magnetic susceptibility (4–300 K) and the data were fitted by least-squares to a susceptibility equation derived from the spin Hamiltonian, H = −2 JS 1 · S 2 . The exchange integral J was found to be −321.5 cm −1 for 1 , −95.3 cm −1 for 2 , −26.5 cm −1 ( 3 ), −5.6 cm −1 ( 4 ) and −5.5 cm −1 ( 5 ). It was observed that − J decreases in the order N 3 − > − O 2 CC 6 H 5 > Im − > OH − ≈ Br − .

Synthesis and properties of one-dimensional Ni(II) and Ni(II)Cu(II) complexes linked by hydrogen bond

Four dithiooxalato (Dto) bridged one-dimensional Ni(ll) and Ni(ll)Cu(ll) complexes (Me6[14]dieneN4)Ni2(Dto)2) (1), (Me6[14]dieneN4)CuNi(Dto)2 (2), (Me6[14]aneN4)Ni2(Dto)2 (3), and (Me6[14]aneN4)CuNi(Dto)2 (4), were synthesized. These complexes have been characterized by elemental analysis, IR, UV and ESR spectra. The crystal structure of complex3 was determined. It crystallizes in the monoclinic system, space group C2/c with a = 2. 2425(4) nm,b = 1.0088(2) nm,c= 1.4665(3) nm, β= 125.32(3)δ Z = 4;R = 0.076, Rw = 0.079. In the complex, Ni(1) coordinates four sulphur atoms of two Dto ligands in plane square environment. Ni(2) lies in the center of macrocyclic ligand. For Dto ligand, two sulphur atoms coordinate Ni(1), and O(1) coordinates Ni(2) and forms weak coordination bond. O(2) is linked to N(2) of macrocyclic ligand through hydrogen bond.