Zhaoping Ni

Observation of magnetic bistability in polymorphs of the [Ni(dmit)(2)](-) complexes.

Four ion-pair complexes of [Ni(dmit)(2)](-) with [NO(2)bzql](+) have been obtained, which belong to two kinds of polymorph forms, [NO(2)bzql][Ni(dmit)(2)] (1alpha and 1beta) and [NO(2)bzql][Ni(dmit)(2)].CH(3)COCH(3) (2alpha and 2beta) (where dmit = 2-thioxo-1,3-dithiole-4,5-dithiolate and [NO(2)bzql](+) = 1-(4-nitrobenzyl)quinolinium). Though 1alpha, 2alpha, and 2beta all show anionic dimerization structures at room temperature, they have different anionic and cationic arrangement fashions, which give rise to different magnetic behaviors for these polymorphs or pseudo-polymorphs. Compounds 1alpha, 1beta, and 2alpha exhibit magnetic bistabilities. In particular, 1alpha has a hysteretic loop at approximately 55 K, while 2beta does not display a spin transition in the 2-300 K range. On the basis of the crystal structure data of 2alpha in high- and low-temperature phases, the magnetic coupling feature within the [Ni(dmit)(2)](-) spin dimer was explored with the broken-symmetry approach at the UBPW91/LANL2DZ level; combined with the experimental data and theoretical analyses, the relationship between the magnetic coupling nature and the stacking pattern of [Ni(dmit)(2)](-) anions as well as the origin of the phase interconversion are discussed.

Syntheses and crystal structures of two new nickel 1,2,5-thiadiazole-3, 4-dithiolate complexes as benzylpyridinium salts

Two new complexes, [BrBzPy]2[Ni(tdas)2] (1) and [BrFBzPy]2[Ni(tdas)2] (2), have been prepared by reaction of disodium 1,2,5-thiadiazole-3,4-dithiolate (Na2tdas), NiCl2·6H2O and 1-(4′-bromobenzyl) pyridinium bromide (BrBzPyBr) or 1-(4′-bromo-2′-fluorobenzyl)pyridinium) bromide (BrFBzPyBr). Crystallographic data for 1: monoclinic, P21 /c, a = 11.333(1), b = 12.602(1), c = 12.267(1) Å, β = 115.65(1)°, V = 1579.4(18) Å3, Z = 4. Data for 2: triclinic, , a = 7.437(2), b = 10.382(2), c = 11.330(2) Å, α = 110.07(3), β = 92.58(3), γ = 93.32(3)°, V = 818.5(2) Å3, Z = 1. In the complexes, the [Ni(tdas)2]2− anion exhibits a quasi-planar structure. The topology of the countercation results in different stacks of molecules in the complexes.

Synthesis and crystal structure of metal complexes of Schiff bases derived from Glycylglycine and Salicylaldehyde [Ni(H2O)6(Ml)2]·nH2O (M = Cu, Ni; L = C11H9N2O4)

Complexes [Ni(H2O)6(ML)2]·nH2O (M = Cu, Ni; L = Schiff base derived from glycylglycine and salicylaldehyde, C11H9N2O4) were synthesized and characterized. The [Ni(H2O)6(CuL)2]·10H2O complex 1 crystallized in the space group , with a = 7.217(1), b = 11.674(1), c = 12.678(1) Å, α = 66.56(1), β = 76.60(1), γ = 80.46(1)°, and Z = 1. The [Ni(H2O)6(NiL)2]·2H2O complex 2 crystallized in the group P2(1)/c, with a = 10.564(2), b = 20.246(4), c = 6.965(2) Å, β = 103.14(1)°, and Z = 2. Hydrogen bonding involving [ML]−, Ni(H2O)6 2+ and molecular water forms a three-dimensional (3D) supermolecule. The determination of variable-temperature magnetic susceptibilities indicates an antiferromagnetic interaction between the metallic atoms of 1, and a corresponding ferromagnetic interaction for 2.

Intramolecular photo-substitution in the inclusion compound of mono[6-deoxy-6-(2-aminoethyl thio-1,2-dicyane ethylenylthio)]-β-cyclodextrin with cyclopentadienyl manganese tricarbonyl in DMF solution

Abstract A novel host of β-cyclodextrin (β-CD) derivative, mono[6-deoxy-6-(2-aminoethyl thio-1,2-dicyane ethylenylthio)]-β-CD ( 3 ), and its inclusion compound 4 with cyclopentadienyl manganese tricarbonyl (CpMn I (CO) 3 ) have been prepared and characterized by spectroscopic methods. It is experimentally evident that the inclusion complexation stabilized the guest extremely when complex 4 was heated. Upon irradiation of inclusion compound 4 in DMF solution, an interesting intramolecular photo-substitution resulting in the formation of a self-stabilized compound mono[6-deoxy-6-(2-aminoethyl thio-1,2-dicyane ethylenylthio)]-β-CDMn II Cp(DMF) 2 ( 7 ) was observed. Based upon a double-recognition between the host and the organometallic guest, compound 7 became very stable in DMF solution.

Crystal structure and spectroscopic properties of a new syn-anti carboxylate-bridged polymeric chain copper(II)–glycylglycine complex

A new polymer complex of copper(II)–glycylglycine {[Cu(glygly)(H2O)][Cu(glygly)(H2O)2]} n ·5nH2O (1) is reported. It crystallizes in the P21/c space group, with a = 14.669(2), b = 9.8480(10), c = 14.053(2) Å, β = 102.730(10)° and Z = 4. Compound 1 consists of [Cu(glygly)(H2O)] n 1D carboxylate-bridged polymeric chains, monomer Cu(glygly)(H2O)2 molecules which form hydrogen-bonded chains and uncoordinated water molecules. In all cases, the geometry around copper(II) is a slightly distorted square pyramid with the water oxygen at the apex of the pyramid. The ESR, UV-Vis and IR spectroscopy of the compound were also studied.

Synthesis and characterization of a dipeptide–copper(II)– 2-aminomethylbenzimidazole ternary complex

A new ternary complex [Cu(glygly)(AMBZ)(H2O)]Cl·H2O (1) (glygly = glycylglycine anion, AMBZ =  2-aminomethylbenzimidazole) has been prepared and characterized by single-crystal X-ray diffractometry and ESR, electronic and IR spectroscopy. The copper(II) ion has a slightly distorted square-pyramidal coordination, being equatorially coordinated by the bidentate 2-aminomethylbenzimidazole and the bidentate glycylglycine anion and axially by a water molecule. The individual complex molecules are hydrogen bonded to their neighbors, forming a polymeric hydrogen-bonded lattice. Spectroscopic data are in accordance with the crystal structure.

Synthesis, crystal structure and magnetic properties of [1-(2′,4′-dichlorobenzyl)-3-methylpyridinium] [Ni(mnt)2] complex (mnt2− = maleonitriledithiolate)

A new ion-pair complex, [DiClBzMePy][Ni(mnt)2] (1) ([DiClBzMePy]+ = 1−(2′4′-dichlorobenzyl)-3-methylpyridinium; mnt2− = maleonitriledithiolate), has been prepared. The anion and [DiClBzMePy]+ cations of Complex 1 stack into well-segregated columns in the solid state, and the Ni(III) ions form a 1D zigzag chain within a anion through Ni···S, S···S and Ni···S···Ni interactions. The anion–anion, anion–cation and cation–cation contacts may play important roles in the crystal packing. Variable temperature magnetic susceptibilities measured at 75–300 K reveal that Complex 1 exhibits antiferromagnetic behavior.

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) Å, β = 102.42(3)°, V = 1644.8(6) Å3, Z = 2. Data for 2: monoclinic, P21/n, a = 7.399(2), b = 19.024(4), c = 12.224(2) Å, β = 94.62(3)°, V = 1715.0(7) Å3, 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.

Preparation, crystal structure and magnetic properties of a maleonitriledithiolate salt of the 1-methyl-3-benzylimidazolium cation with a novel structural motif

A new ion-pair complex, 1-methyl-3-benzylimidazolium bis(maleonitriledithiolato)nickelate(III), has been synthesized and characterized by IR spectroscopy and X-ray crystallography. The compound crystallizes in the triclinic space group P with a = 13.280(1), b = 14.906(1), c = 17.949 (2) Å, α = 108.02(1), β = 101.55(1), γ = 90.51(1)° and Z = 6. There are three inequivalent [Ni(mnt)2]− anions in the structure of the complex, two of them are stacked along the b axis with an AACC-type repeat unit, the other lies approximately orthogonal to the stack. Anions form three kinds of dimers with short Ni···Ni distances, leading to such strong spin coupling interactions that the complex is diamagnetic.

Synthesis, crystal structure and magnetic properties of [1-(4′-bromobenzyl)-4-methylquinolinium] [Ni(mnt)2] complex (mnt2 − =maleonitriledithiolate)

A new ion-pair complex, [BrBzMeQl][Ni(mnt)2] (1) ([BrBzMeQl]+ = 1-(4′-bromobenzyl)-2-methylquinolinium; mnt2− = maleonitriledithiolate), has been prepared and characterized. X-ray diffraction analysis shows that the Ni(mnt)2 anion and [BrBzMeQl]+ cations of 1 form completely segregated stacking columns, with the Ni ··· Ni distances alternating between 3.717 and 4.466 Å in the Ni(mnt)2 stacking column. The variable-temperature magnetic susceptibilities of 1 have been measured over the range 75–300 K and the results reveal that the complex exhibits antiferromagnetic behavior.