Yanmei Chen

Titanium and zirconium amido complexes supported by imidazole-containing ligands: syntheses, characterization and catalytic activities

A series of new titanium and zirconium amido complexes, incorporating 4,5-diphenyl-2-(2-pyridinyl)-1H-imidazole (HL1), 4,5-bis(4-chlorophenyl)-2-(2-pyridinyl)-1H-imidazole (HL2), 4,5-bis(4-methoxyphenyl)-2-(2-pyridinyl)-1H-imidazole (HL3) and 4,5-bis(2-methoxyphenyl)-2-(2-pyridinyl)-1H-imidazole) (HL4) as the ancillary ligands, have been prepared and are shown to be pre-catalysts for the hydroamination of alkynes. Treatment of Ti(NMe2)4 with 1 equivalent of HL1, HL2, HL3 and HL4, respectively, results in transamination with one dimethylamide group providing Ti(L1)(NMe2)3 (1), Ti(L2)(NMe2)3 (2), Ti(L3)(NMe2)3 (3), and Ti(L4)(NMe2)3·THF (4·THF). Reaction of Ti(NMe2)4 with 2 equivalents of HL1, HL2, HL3 and HL4, respectively, leads to production of titanium bisamido complexes Ti(L1)2(NMe2)2·THF (5·THF), Ti(L2)2(NMe2)2·THF (6·THF), Ti(L3)2(NMe2)2·THF (7·THF), and Ti(L4)2(NMe2)2 (8). Similarly, complexes Zr(L1)(NMe2)3 (9), Zr(L1)2(NMe2)2·1.5THF (10·1.5THF), Zr(L2)2(NMe2)2·0.5THF (11·0.5THF), and Zr(L3)2(NMe2)2·0.5THF (12·0.5THF) are generated by addition of 1 or 2 equivalents of the corresponding ligands to Zr(NMe2)4. All compounds have been characterized by elemental and spectroscopic analyses. The solid-state structures of compounds 2 and 6·THF have been further established by single X-ray diffraction analyses. The catalytic activities of 2 and 6·THF towards the hydroamination of alkynes were explored. Complexes 2 and 6·THF were found to be active pre-catalysts for the hydroamination reactions. Complex 2 showed higher catalytic activity and gave highly Markovnikov selective hydroamination of terminal alkynes.

Heterometallic SrII-MII (M=Co, Ni, Zn and Cu) Coordination Polymers: Synthesis, Temperature-Dependent Structural Transformation, and Luminescent and Magnetic Properties

The use of pyridine-2,4-dicarboxylic acid (H2 pydc) in the construction of Sr(II) and Sr(II) -M(II) (M=Co, Ni, Zn and Cu) coordination polymers is reported. Eight complexes, that is, [Sr(pydc)H2 O]n (1), [MSr(pydc)2 (H2 O)2 ]n (M=Co (2), Ni (3), Zn (4)), [ZnSr(pydc)2 (H2 O)7 ]n ⋅4u2009nH2 O (5), [SrCu(pydc)2 ]n (6), [SrCu(pydc)2 (H2 O)3 ]n ⋅2u2009nH2 O (7), and [Cu3 Sr2 (pydc)4 (Hpydc)2 (H2 O)2 ]n (8), have been synthesized via dexterously choosing the appropriate strontium sources and transition metal salts, and rationally controlling the temperature of the reaction systems. Complexesu20051, 2 (3, 4), 6, and 8 display four types of 3-D framework structures. Complexesu20055 and 7 exhibit a 2-D network and a 1-D chain structure, respectively. The 2-D complexu20057 can be reversibly transformed into 3-D compound 6 through temperature-induced solvent-mediated structural transformation. The luminescent property studies indicated that complexu20051 shows a strong purple luminescent emission and 4 exhibits a strong violet luminescence emission. The magnetic properties of 2, 3, and 8 were also studied. Antiferromagnetic M(II) ⋅⋅⋅M(II) interactions were determined for these complexes.

A series of tetranuclear [Ln4] clusters with defect-dicubane cores including a Dy4 single-molecule magnet

A series of tetranuclear lanthanide compounds, [Ln4(μ3-OH)2L4(NO3)2(DMF)2] (H2L = 2-(2-hydroxy-3-methoxybenzylideneamino)phenol; Ln = Dy (1); Tb (2); Er (3); and Gd (4)), have been prepared under hydrothermal conditions. X-ray crystal structure analysis reveals that 1–4 are polymorphs. The cores of the structures can be described as co-planar defect-dicubane. The solid-state luminescent properties indicate that the LnIII ions have very deep influence on the luminescence of H2L. The magnetic properties for 1–4 were studied. The Dy4 complex exhibits single-molecule magnet behavior. Graphical abstract A series of tetranuclear lanthanide compounds have been prepared. The Dy4 complex exhibits single-molecule magnet behavior.

Titanium complexes supported by imidazo[1,5-a]pyridine-containing pyrrolyl ligand as catalysts for hydroamination and polymerization reactions, and as an antitumor reagent

A new imidazo[1,5-a]pyridine-containing pyrrolyl ligand HL (HL = 3-(1H-pyrrol-2-yl)imidazo[1,5-a]pyridine) was synthesized and employed in the organometallic chemistry of titanium. The syntheses, structures, catalytic properties and antitumor activity of three titanium complexes supported by HL are reported. Reactions of Ti(NMe2)4 and Ti(NEt2)4 with 2 equivalents of HL, led to the production of titanium bisamido complexes TiL2(NMe2)2 (1) and TiL2(NEt2)2 (2), respectively. Treatment of Ti(OiPr)4 with 2 equivalents of HL resulted in the formation of TiL2(OiPr)2 (3). All complexes were characterized by elemental analyses and NMR studies. The solid-state structures of 2 and 3 were further established by single X-ray crystallography. The titanium bisamido complexes 1 and 2 are shown to be good pre-catalysts for the hydroamination of alkynes. Complex 1 was found to be an active catalyst for the ring-opening polymerization of e-caprolactone. The cytotoxicity activities of 3 towards the tumor cells HCT-116, PC3 and MCF-7 were measured. Complex 3 exhibited good antitumor properties.

A series of ZnII and CoII complexes based on 2-(imidazo[1,5-a]pyridin-3-yl)phenol: syntheses, structures, and luminescent and magnetic properties

The employment of 2-(imidazo[1,5-a]pyridin-3-yl)phenol (HIPP) in ZnII and CoII coordination chemistry is reported. A series of complexes of compositions, [Zn(HIPP)2Cl2] (1), [Zn2(IPP)4] (2), [Co2(HIPP)4(SO4)2] (3), [Co3(IPP)6] (4), and [Co2(IPP)2(CH3COO)2]n (5), have been synthesized via choosing appropriate metal salts and different solvents. Complexes of various nuclearities are obtained from mono-, di-, trinuclear complexes to 1-D chain polymer. UV–vis absorption properties have been investigated and rationalized by density functional theory and time-dependent DFT calculations. In addition, luminescence studies suggested strong emissions for 1, 2, and 3 in the solid state at room temperature. Variable temperature (2.0–300u2009K) magnetic studies for 3, 4, and 5 indicate weak antiferromagnetic coupling between the metal centers in 3 and 5, and weak ferromagnetic CoII⋯CoII exchange interactions in 4. Graphical Abstract Five coordination complexes based on 2-(imidazo[1,5-a]pyridin-3-yl)phenol were synthesized and characterized; their luminescent and magnetic properties were studied.

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.

Spatial resolution measurement of triple-GEM detector and diffraction imaging test at synchrotron radiation

A triple-GEM detector with two-dimensional readout is developed. The detector provides high position resolution for powder diffraction experiments at synchrotron radiation. Spatial resolution of the detector is measured in the lab using a 55Fe X-ray source. A resolution of about 110 μm FWHM is achieved. The energy resolution is better than 27% for 5.9 keV X-rays. The detectors validity under illumination of photons in particular energy range is verified using a Cu X-ray tube. Imaging of the head of a wire stripper with X-ray tube demonstrates its imaging ability. A diffraction imaging experiment using the sample of powder SiO2 is successfully carried out at 1W2B laboratory of Beijing Synchrotron Radiation Facility (BSRF). Different diffraction rings are clearly seen under various X-ray energies.

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.

CCDC 640234: Experimental Crystal Structure Determination

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