Xiaoming Ren

Peculiar magnetic behavior in ion-pair complex [1-(4′-fluorobenzyl)pyridinium][Ni(mnt)2] (mnt2− = maleonitriledithiolate)

An ion-pair complex [FBzPy][Ni(mnt)2], where [FBzPy]+ = 1-(4-fluorobenzyl)pyridinium and mnt2- = maleonitriledithiolate, forms a discrete stacking column and shows a peculiar magnetic transition from paramagnetic to diamagnetic around 90 K.

Spontaneous magnetization in [1-(4-cyanobenzyl)pyridinium][Pt(mnt)2]: synthesis, crystal structure and magnetic property

Abstract A new complex [1-(4-cyanobenzyl)pyridinium][Pt(mnt) 2 ] ( 1 ), in which mnt 2− xa0=xa0maleonitriledithiolate, has been prepared and characterized. In the solid state, anions and cations of 1 form completely segregated stacking column, and the [Pt(mnt) 2 ] − anion column behaves as one-dimensional (1-D) spaced magnetic chains. 1 spontaneously magnetizes at low temperature, which may arises from spin canting.

Synthesis, crystal structure and magnetic properties of a novel one-dimensional nickel(III) chain complex showing ferromagnetic ordering at low temperature

A novel ferromagnetic complex [BrFBzPy][Ni(mnt)2], where [BrFBzPy]+ n= 1-(4′-bromo-2′-fluorobenzyl)pyridinium and mnt2− n= maleonitriledithiolate, has been prepared and characterized. In the crystal structure the most prominent feature is that the [Ni(mnt)2]− anions and [BrFBzPy]+ cations form a well-separated stacking column along the c-axis, within which the [Ni(mnt)2]− anions are uniformly spaced to give a one-dimensional (1-D) chain structure. The magnetic properties of this complex have been investigated in the temperature range 1.8–300 K and its magnetization studies show there exists ferromagnetically coupled interactions within the [Ni(mnt)2]− anion chain (J n= 42.2 cm−1), and antiferromagnetically coupled interactions between [Ni(mnt)2]− nanion chains (Jeff n= n−4.78cm−1). The temperature dependences of the ac susceptibility revealed that this 1-D chain system is ferromagnetically ordered around 2 K and χac measurements performed at different magnetic fields and frequencies suggest that there may coexist a degree of spin glass behaviour at low temperature.

Unambiguous cis-coordination of mono- and bi-dentate Lewis bases to Ni(SN)2 Schiff-base complexes derived from S-alkyl dithiocarbazate

The bidentate Schiff-base ligand, HL1, prepared by condensation of equivalent molar amount of o-nitrobenzaldehyde with S-benzyl dithiocarbazate, yielded the neutral square-planar complex, NiL12 (1) in the presence of Ni(OAc)2·4H2O. Addition of pyridine to (1) and phenanthroline (phen) to NiL (3) afforded the adducts NiL12(py)2·1.5H2O (2) and NiL(phen) (4), respectively, where H2L is a known quadridentate (NS)2 ligand. Single crystal X-ray analysis of (2) and (4) showed that the pyridine rings and phen occupy cis-positions in the octahedral adducts. In both cases, one N–Ni bond in the parent Ni(NS)2 complexes is severely perturbed, thus facilitating cis-addition of the Lewis bases. The present results together with those reported previously show that cis-addition is preferred in the addition reaction of Ni(NS)2 Schiff-base complexes derived from S-alkyl dithiocarbazate. Addition of pyridine and 2,2′-bipyridine to NiL (3) is also discussed.

Synthesis, spectroscopic characterization and X-ray crystal structure of vanadylpolymolybdophosphates with monocapped Keggin polyanion [PMo5V7O40(VO)]7−

Abstract The preparation of the heteropolyoxometalates K6[HPMo5V7O40(VO)]·16H2O (1), (n-Bu4N)4[H3PMo5V7O40(VO)] (2) and (CN3H6)6[HPMo5V7O40(VO)]·4H2O (3) is described. Compounds 2 and 3 have been characterized by X-ray diffraction methods. Both compounds contain a monocapped Keggin anion. For compound 2 the capping Vue605O group is disordered in six sites, while there are two types of sites for the capping Vue605O group for compound 3. The IR spectra have been investigated.

Synthesis, crystal structure and magnetic properties of [RBzPy] [Fe(mnt)2] complexes ([RBzPy]+ = 1-(4′-R-benzyl)pyridinium, R = NO2 and CL; mnt2− = maleonitriledithiolate)

Ion-pair complexes consisting of the [Fe(mnt)2]− anion and [RBzPy]+ cations [R = NO2(1) or Cl (2)] have been prepared and characterized by elemental analysis and i.r. spectroscopy. The single crystal structure of (1) shows that the [Fe(mnt)2]− anions are dimeric, and that the coordination geometry of each Fe atom is square pyramidal. The most significant structural feature of (1) is that anions and cations form completely separate columns and π–π interactions occur within the cation columns. Thermal variations of χmT for the complexes indicated antiferromagnetic coupling within the dimer.

The Inclusion Complex of Ferrocene with a Dithiolene Functionalized β-Cyclodextrin

A new βcyclodextrin derivative with the anion side-arm, mono[6-deoxy-6-(2-sodium thio-1,2-dicyane ethylenylthio)]-βcyclodextrin (6-mnt-βCD), and its inclusion complex with ferrocene (6-mnt-βCD/Fc), have been prepared and characterized by elemental analysis, IR spectroscopy, UV spectroscopy, mass spectrometry, 13C-NMR spectroscopy, thermogravimetry, and cyclic voltammetry (CV). Thermogravimetry analysis of the compound shows that the thermal stabilities of both the host and the guest in the inclusion complex have been greatly improved due to an additional interaction between the side-arm of the host and the guest. The interplay between the guest and the host with side-arm in the complex resulted in smaller positive potential shifts in CV compared to that in the inclusion complex βCD/Fc.

Di­chloro­(di­methyl­form­amide)[2-hydroxy-5-nitro-N-(8-quinolyl)­salicyl­aldiminato]­iron(III)

In the title complex, [FeCl2(C16H10N3O3)(C3H7NO)], the FeIII ion is in an octahedral environment, with the equatorial plane being defined by the two N and one O atoms of the tridentate ligand 2-hydroxy-5-nitro-N-(8-quinolyl)xadsalicylxadaldxadimine, and a chlorine, the octahedron being completed by the other chlorine and a dixadmethylxadformxadamide (DMF) O atom in axial positions. Non-classical hydrogen bonds between 8-aminoxadquinolyl C—H groups and nitro O and Cl atoms of neighbouring molxadecules generate a layered hydrogen-bonded network.

Solvothermal synthesis, crystal structure and magnetic properties of the one-dimensional coordination polymer Ni(DMBDIZ)(OOCMe)2 (DMBDIZ = 2,6-dimethylbenzo[1,2-d:4,5-d′]diimidazole)

The solvothermal synthesis and crystal structure of the one-dimensional coordination polymer Ni(DMBDIZ) (OOCMe)2 (DMBDIZ = 2,6-dimethyl-benzo[1,2-d:4,5-d′]diimidazole) are described. Each nickel ion is located in pseudo-octahedral geometry formed by four oxygen atoms from two bidentate acetate anions and two trans-related tertiary nitrogen donors from two different DMBDIZ ligands. The DMBDIZ entity acts as a trans exo-bidentate ligand and bridges the nickel ions to form a uniform linear chain with Ni···Ni separation = 8.703 Å. The hydrogen bonding between the acetate anions and the ligands contributes to the enhancement of the structural dimensionality. Variable-temperature magnetic susceptibility measurements (2.0–300 K) reveal the presence of a very weak ferromagnetic interaction between the magnetic centers.

Syntheses and crystal structures of two maleonitriledithiolate complexes containing the 1-(R-benzyl)pyrazinium cation (R = 4′-nitro or 4′-bromo)

The complexes [NO2BzPz]2[Ni(mnt)2] (1) and [BrBzPz]2[Pd(mnt)2] (2) have been prepared by reaction of Na2mnt, NiCl2·6H2O or PdCl2, and the corresponding 1-(R-benzyl)pyrazinium bromide salt (R = 4′-nitro, R = 4′-bromo). Crystallographic data for 1: monoclinic, P21/n, a = 7.3494(15), b = 15.223(3), c = 15.054(3)u2009Å, β = 102.42(3)°, V = 1644.8(6)u2009Å3, Z = 2. Data for 2: monoclinic, P21/n, a = 7.399(2), b = 19.024(4), c = 12.224(2)u2009Å, β = 94.62(3)°, V = 1715.0(7)u2009Å3, Z = 4. In both complexes, the [M(mnt)2]2− anion has a centre of symmetry at the metal atom and two cations are related to each other by the symmetry centre. The [M(mnt)2]2− anion exhibits a quasi-planar structure in both complexes, which show similar crystal packing.