Yahong Li

Wheel-like MnII6 and NiII6 complexes from the use of 2-pyridinealdoxime and carboxylates

The employment of 2-pyridinealdoxime, (py)C(H)NOH, in nickel(II) and manganese(II) carboxylate chemistry under solvothermal conditions is reported. The syntheses, crystal structures and magnetochemical characterization (for two representative compounds) are described for [Ni(6)(O(2)CMe)(6){(py)C(H)NO}(6)].H(2)O (1.H(2)O), [Ni(6)(O(2)CPh)(6){(py)C(H)NO}(6)].2EtOH (2.2EtOH), [Ni(6){(4-Cl)O(2)CPh}(6){(py)C(H)NO}(6)].2EtOH (3.2EtOH) and [Mn(6)(O(2)CMe)(6){(py)C(H)NO}(6)].H(2)O (4.H(2)O), where (4-Cl)PhCO(2)(-) is 4-chlorobenzoate. The reactions of M(O(2)CMe)(2).4H(2)O (M = Ni, Mn) with one equivalent of (py)C(H)NOH in EtOH at 120 degrees C under autogenous pressure give isostructural 1.H(2)O and 4.H(2)O. Complexes 2.2EtOH and 3.2EtOH were obtained from the 1 : 1 : 1 Ni(O(2)CMe)(2).4H(2)O/{(py)C(H)NOH/(X)PhCO(2)H reaction mixtures in EtOH under solvothermal conditions (X = H, 4-Cl). The structurally similar clusters 1-4 have a wheel-like topology with the six metal ions in a chair conformation. Each metal site is bound to four oxygen and two nitrogen atoms; the donor atoms come from two carboxylate oxygens, two oximate oxygens, one pyridyl nitrogen and one oximate nitrogen atom. The carboxylate ligands show the syn, syn eta(1):eta(1):mu mode, while the (py)C(H)NO(-) ions behave as eta(1):eta(1):eta(2):mu(3) ligands. Each metal...metal vector is bridged by one carboxylate group, one mu-O derived from a (py)C(H)NO(-) ligand and by one diatomic oximate-NO- group from an adjacent (py)C(H)NO(-) group. The IR spectra of the complexes are discussed in terms of the coordination modes of the ligands. Variable-temperature, solid-state dc magnetic susceptibility studies were carried out on polycrystalline samples of 1 and 4. The data in the 2.0-300 K range have been fit to a model with one J value revealing moderate (1) or weak (2) antiferromagnetic M(II)...M(II) exchange interactions. This work demonstrates the synthetic potential of combining (py)C(H)NOH with carboxylate ligands and the usefulness of solvothermal techniques in 3d-metal cluster chemistry.

Experimental design in the analysis of interferential effects for the determination of Sr in high Ca/Sr ratio brine by inductively coupled plasma atomic emission spectroscopy technique

The ICP-AES technique and experimental design were employed to precisely determine the content of strontium in high Ca/Sr ratio oil field brine of Qaidam basin (Qinghai province, western China). From the statistical analysis using six factor factorial, it was found that Ca2+ is the significant interfering element for the recovery of strontium. Accurate strontium content was derived by eliminating the interference contribution according to the influencing model. The experimental results indicate that, under optimal conditions, the ICP-AES method for strontium determination has low LOD and LOQ, and the precision and accuracy are good with the relatively standard deviation below 1% and recovery between 98.0%u2009∼u2009105.0%.

catena-Poly[diimidazolium [bis­(μ-pyridine-2,5-dicarboxyl­ato)bis­[diaqua­praseodymate(III)]]-bis­(μ-pyridine-2,5-dicarboxyl­ato)]

The title compound {(C3H5N2)2[Pr2(C7H3NO4)4(H2O)4]}n, has a chain structure featuring a dimeric unit consisting of two PrIII atoms within a dodecahedral environment. Each of the metal cations is coordinated by two N atoms and two O atoms from two pyridine-2,5-dicarboxylate ligands, two O atoms from another two pyridine-2,5-dicarboxylate ligands and two water O atoms. The PrIII ions are bridged by two ligands along the c axis, forming the dimeric unit, and these are connected by four ligands along the b axis, forming a chain. N—H⋯O and O—H⋯O hydrogen bonds are found in the structure.

Bis[N,N′-bis­[(1H-pyrrol-2-yl)methyl­ene]cyclo­hexane-1,2-diamine]titanium(IV) tetra­hydro­furan solvate

In the title compound, [Ti(C16H18N4)2]·C4H8O, the TiIV ion is chelated by two Schiff base dianions with a TiN8 distorted square-antiprismatic coordination geometry. The two cyclohexane rings assume the typical chair conformation. No hydrogen bonding is observed in the crystal structure.

Bis(1,5-diphenyl­carbazonato)di­methano­lcobalt(II)

The structure of the title compound, [Co(C13H11N4O)2(CH3OH)2], is a mononuclear six-coordinated octahedral cobalt(II) complex of C i molecular symmetry. The CoII ion is coordinated by two N atoms and two O atoms from two 1,5-biphenylcarbazide ligands, and two O atoms from two methanol molecules. Two diphenylcarbazidate ligands and the central CoII ion form the basal plane, with the two methanol molecules located in axial positions. The crystal packing is defined by bifurcated O—H⋯N hydrogen bonding and intramolecular N—H⋯O interactions.

Co(II) and Ni(II) complexes incorporating N-acetimidoylacetamidine ligand: Synthesis and structures

Two new square planar complexes with the formula Co(L)2 · CH3OH (1) and Ni(L)2 · CH3OH (2) (HL = HN{C(Me)=NH}2 = N-acetimidoylacetamidine) have been synthesized by solvothermal reactions in methanol/acetonitrile. N-acetimidoylacetamidine ligand was derived from the self-condensation reaction of acetonitrile, and the reaction was promoted by the cooperation of M(II) (M = Co in 1 and M = Ni in 2) with diphenylcarbazide. 1 and 2 are characterized by single crystal X-ray diffraction, elemental analysis and infrared spectrum. Both complexes crystallize in the monoclinic space group P21/c with a = 9.329(6) Å, b = 11.494(7) Å, c = 13.040(8) Å, β = 92.945(11)°, V = 1396.3(16) Å3 and Z = 4 for 1, and a = 9.323(4)Å, b = 11.512(5) Å, c = 13.020(6)Å, β = 92.819(7)°, V = 1395.7(10)Å3 and Z = 4 for 2.

Bis{2-[(4-chloro­phen­yl)imino­meth­yl]pyrrol-1-ido-κ2N,N′}bis­(dimethyl­amido-κN)titanium(IV) toluene monosolvate

The mononuclear title compound, [Ti(C11H8ClN2)2(C2H6N)2]·C7H8, was synthesized by the reaction of N-(4-chlorophenyl)-2-pyrrolylcarbaldimine with Ti(C2H6N)4. The TiIV ion is situated on a twofold rotation axis and displays a distorted octahedral geometry defined by four N atoms from two 2-[(4-chlorophenyl)iminomethyl]pyrrol-1-ide ligands and two N atoms from two dimethylamine ligands. The Ti—Npyrrole bond length [2.1041u2005(19)u2005Å] is longer than the Ti—Ndimethylamine bond length [1.9013u2005(19)u2005Å]; the imine N atom exhibits the longest Ti—N bond [2.3152u2005(17)u2005Å]. The toluene solvent molecule is located on a twofold rotation axis running through the C atom of the methyl group. Consequently, the H atoms of the latter are rotationally disordered. The compound contains no markable hydrogen-bonding interactions.

Bis[2-(benzyl­imino­meth­yl)pyrrol-1-ido-κ2N,N′]bis­(dimethyl­amido-κN)titanium(IV)

The mononuclear title complex, [Ti(C2H6N)2(C12H11N2)2], was synthesized by the reaction of 1-phenyl-N-[(pyrrol-2-yl)methylidene]methanamine with Ti(NMe2)4. The TiIV atom is coordinated in a distorted octahedral geometry by four N atoms from two derivatized methanamine ligands and two N atoms from two dimethylamide ions. The dihedral angles between the pyrrole and phenyl rings in the bidentate ligands are 62.36u2005(9) and 78.32u2005(8)°. In the crystal, a weak π–π stacking interaction [centroid–centroid distance = 3.864u2005(2)u2005Å] involving centrosymmetrically related molecules is observed.

Trichloridotris{N-[phen­yl(pyridin-2-yl)­methyl­idene]hydroxyl­amine-κ2N,N′}samarium(III)

The SmIII ion in the title compound, [SmCl3(C12H10N2O)3], shows a coordination number of nine with a slightly distorted tricapped trigonal prismatic geometry based on a Cl3N6 donor set. The molecular structure is stabilized by three intramolecular O—H⋯Cl hydrogen bonds.