Chi Zhang

Syntheses and NLO properties of 1D heterothiometallic anionic W/S/Ag clusters possessing solvento-ytterbium cation-directed isomeric skeletons

The sequential addition to [WS4]2− of different solvent-coordinated ytterbium cations as templates and silver iodide as Ag+ source afforded the heterothiometallic clusters {[Yb(DMSO)7][Yb(DMSO)8][W6S24Ag6]}n1 (DMSO = dimethyl sulfoxide), {[Yb(DMF)8][W3S12Ag3]}n2 (DMF = N,N′-dimethylformamide) and {[Yb(HMP)4(NO3)2][WS4Ag]}n3 (HMP = hexamethylphosphoramide) with isomeric anionic skeletons and in high yields. 1–3 have been fully characterized by elemental analysis, IR and UV-vis spectroscopies, and single-crystal X-ray crystallographic studies. 1 possesses a 1D anionic helical chain with unusual hexavalent repeat units, a structure directed by the combination of seven- and eight-coordinated ytterbium cations, 2 exhibits an unusual 1D anionic zigzag chain, while 3 contains a 1D anionic linear chain. Z-scan studies (532 nm, 8 ns pulses) reveal that 1 and 2 possess strong third-order nonlinear optical properties. Density functional theory and time-dependent density functional theory calculations at the B3LYP/LanL2DZf+6-31G* level were performed on 1–3 to rationalize their experimental absorption spectra.

Microstructure and mechanical properties of surface layer of M50NiL steel plasma nitrided

Abstract The quenched M50NiL steel specimens have been plasma nitrided at temperatures from 460 to 590°C for 4 h under a constant mixture gaseous supply of 0·05N2–0·4H2 L min−1. The effects of the treatment temperature on the microstructure, microhardness and wear resistance of the surface nitrided layers are studied. The results show that the plasma nitrided layer includes only the diffusion layer without conventional compound layer. The surface hardness is significantly enhanced. α′-Fe and γ′-Fe4N phases in surface layer are formed at relatively low nitriding temperatures (460–560°C), while a low nitrogen phase FeN0·076 forms when the nitriding temperature exceeds 575°C. With the increase in nitriding temperature, the nitrided layer thickness increases, whereas both the surface and core microhardness of the nitrided specimens decreases. The wear resistance of specimens can also be improved significantly by plasma nitriding.

Tris(2,2′-bipyridine-κ2N,N′)cobalt(III) octa­cyanido­tungstate(V)

In the title compound, [Co(C10H8N2)3][W(CN)8], the Co atom (..2 site symmetry) is coordinated by six N atoms from three 2,2′-bipyridine ligands in an octahedral geometry; the Co—N bond distances range from 1.926u2005(2) to 1.939u2005(2)u2005Å. The W (..2 site symmetry) metal center is coordinated by eight cyanide ligands, resulting in a dodecahedral conformation with W—C distances in the range 1.165u2005(3)–2.176u2005(3)u2005Å. The cations and anions are linked into a three-demensional structure by weak C—H⋯N hydrogen bonds.

μ(3)-Iodo-tri-μ(3)-sulfido-sulfidotris[tris-(4-methoxy-phen-yl)phosphine-κP]tri-copper(I)tungsten(VI) N,N-dimethyl-formide solvate.

A new W/S/Cu cluster, [Cu3WIS4(C21H21O3P)3]·C3H7NO, was formed by the reaction of ammonium tetrathiotungstate(VI), cuprous iodide and tris(4-methoxyphenyl)phosphine in N,N-dimethylformamide. The title compound exhibits a heavily distorted cubane-like skeleton in which the average Cu—I, Cu—S and W—μ3-S distances are 2.934, 2.302 and 2.249u2005Å, respectively. The W atom exhibits tetrahedral geometry, formed by three μ3-S and one terminal S atom; the W—S(terminal) bond length is 2.1426u2005(13)u2005Å. Each Cu atom is coordinated by one P atom from a tris(4-methoxyphenyl)phosphine (mop), two μ3-S and one μ3-I atom, forming a distorted tetrahedral coordination geometry. Some of the mop ligand methyl groups have large librations. Together with the three neutral mop ligands, the title compound is neutral; this contrasts with the all-halogen-coordinated Mo/S/Ag clusters with the same structure, which carry negative charge.

Metal-Cation-Directed Assembly of Two M–I (M = Cu, Ag) Clusters: Structures, Thermal Behaviors, Theoretical Studies, and Luminescence Properties

Two new M–I (Mxa0=xa0Cu, Ag) clusters, {[Ce(DMF)8][Cu8I11]·C2H5OH}n (1) (DMFxa0=xa0dimethylfomamide) and {[Co(DMF)6]4[Ag7I11]2} (2), were synthesized with the direction of solvent-associated metal cations ([Ce(DMF)8]3+ in 1 and [Co(DMF)6]2+ for 2). Clusters 1 and 2 have been well-characterized by elemental analysis, infrared spectroscopy, ultraviolet/visible spectroscopies, single-crystal X-ray diffraction and thermogravimetric analysis. 1 contains the eight-coordinated cations [Ce(DMF)8]3+ and 1D polymeric anionic chain {[Cu8I11]3−}n, which is constructed from [Cu8I11]3− clusters connected with each other through µ3-I bridges and exhibits an interesting wavy chain structure. Cluster 2 consists of the six-coordinated cations [Co(DMF)6]2+ and the dimeric anionic cluster {[Ag7I11]2}8−, which is fabricated by a pair of heptanuclear butterfly-like clusters connected by two Ag–I bridges. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations at the B3LYP/LanL2DZ*+6-31G* level were performed on clusters 1 and 2 to rationalize their experimental absorption spectra. Solid-state luminescence properties of clusters 1 and 2 have also been investigated at room temperature.

A twofold interwoven two-dimensional→two-dimensional (2-D→2-D) cluster-organic network based on the [Cu2I2] cluster and the 4,4'-(diazenediyl)dipyridine ligand: poly[[μ2-4,4'-(diazenediyl)dipyridine]-μ2-iodido-copper(I)].

In the polymeric title compound, [CuI(C(10)H(8)N(4))](n), the Cu(I) atom is in a four-coordinated tetrahedral geometry, formed by two I atoms and two pyridine N atoms from two different 4,4-(diazenediyl)dipyridine (4,4-azpy) ligands. Two μ(2)-I atoms link two Cu(I) atoms to form a planar rhomboid [Cu(2)I(2)] cluster located on an inversion centre, where the distance between two Cu(I) atoms is 2.7781 (15) Å and the Cu-I bond lengths are 2.6290 (13) and 2.7495 (15) Å. The bridging 4,4-azpy ligands connect the [Cu(2)I(2)] clusters into a two-dimensional (2-D) double-layered grid-like network [parallel to the (10-2) plane], with a (4,4)-connected topology. Two 2-D grid-like networks interweave each other by long 4,4-azpy bridging ligands to form a dense 2-D double-layered network. To the best of our knowledge, this interwoven 2-D→2-D network is observed for the first time in [Cu(2)I(2)]-organic compounds.

Metalloligand-induced Synthesis of Two Cu(I)–M (M=Ni, Co) Heterobimetallic Coordination Polymers: Structures, Thermal and Luminescence Properties

Two interesting heterobimetallic coordination polymers (CPs), {[Ni(4-pytpy)2]2[Cu4(N(CN)2)7](NO3)(DMF)(DMSO)(H2O)4}n (1) and {[Co(4-pytpy)(N(CN)2)]2[Cu2(N(CN)2)4]}n (2), have been synthesized based on different metalloligands [M(4-pytpy)2]2+ (M=Ni 1, Co 2) (4-pytpyxa0=xa04′-(4-pyridyl)-2,2′:6′,2″-terpyridine). CPs 1 and 2 have been well characterized by elemental analysis, IR spectroscopy, thermal analysis and single-crystal X-ray diffraction. Both CPs 1 and 2 crystallize in the triclinic crystal system with the P-1 space group but feature different structures. CP 1 exhibits a unique one dimensional double-chain structure, while CP 2 possesses an infinite 2D network structure. It is interesting to note that the metalloligand [Co(4-pytpy)2]2+ in CP 2 was decomposed into [Co(4-pytpy)]2+. Thermal analysis indicates that the chain structure of CP 1 begins to collapse after about 360xa0°C, while CP 2 can be stable up to 300xa0°C. The solid-state luminescence properties of CPs 1 and 2 have also been investigated.

Bis[tris­(ethane-1,2-diamine)nickel(II)] octa­cyanidomolybdate(IV) penta­hydrate

In the title compound, [Ni(C2H8N2)3]2[Mo(CN)8]·5H2O, the NiII ion is coordinated by six N atoms from three ethane-1,2-diamine ligands in a distorted octahedral geometry, while the MoIV atom is coordianted by eight cyanide ligands. The Ni—N bond distances range from 2.1061u2005(18) to 2.1425u2005(18)u2005Å. The Mo—C and C—N distances in the [Mo(CN)8] unit range from 2.154u2005(2) to 2.174u2005(2)u2005Å and 1.149u2005(3) to 1.156u2005(3)u2005Å, respectively. The complex ions and water molecules are linked by weak N—H⋯N/O and O—H⋯N/O hydrogen bonds into a three-demensional structure.

Two Ag(I)–Ni(II) Heterobimetallic Coordination Polymers Based on Metalloligand and Bridging Ligands: Syntheses, Structures and Luminescence Properties

Two new one-dimensional heterobimetallic coordination polymers, {[Ni(2-pytpy)2][Ag2(SCN)4]}n (2-pytpyxa0=xa04′-(4-pyridyl)-2,2′:6′,2′′-terpyridine) and {[Ni(2-pytpy)2][Ag2(N(CN)2)3(NO3)DMSO]}n (DMSOxa0=xa0dimethyl sulfoxide), were synthesized from the reaction of metalloligand [Ni(2-pytpy)2]2+ and Ag+ with bridging ligands (SCN− for 1, N(CN)2− for 2). 1 and 2 were well characterized by elemental analysis, Fourier-transform infrared spectroscopy, thermal analysis and single-crystal X-ray diffraction. The single-crystal X-ray analysis reveals that both 1 and 2 possess one-dimensional (1D) chain structures, which are constructed from metalloligands [Ni(2-pytpy)2]2+ and dinuclear silver structural units ([Ag2(SCN)4] for 1, [Ag2(N(CN)2)3(NO3)DMSO] for 2). These 1D chains are further constructed into 3D supramolecular structures through the intermolecular hydrogen bonds. The solid-state luminescence properties of 1 and 2 were also investigated.

Ligand-Assisted Conformation of Three Interesting Ni–M (M = Ag, Cu) Heterobimetallic Coordination Polymers: Syntheses, Structures, Thermal and Luminescence Properties

Three new heterobimetallic coordination polymers (CPs), {[Ni(4-pytpy)2][Ag(CH3CN)(NO3)](NO3)2(H2O)2}n1 (4-pytpyxa0=xa04′-(4-pyridyl)- 2,2′:6′,2′′-terpyridine), {[Ni(4-pytpy)2][Ag2(4,4′-bipy)](NO3)4(DMSO)4}n2 (4,4′-bipyxa0=xa04,4′-bipyridine), and {[Ni(4-pytpy)2][Cu3(SCN)5](CH3CN)(DMF)(H2O)0.5}n3, were synthesized from metalloligand [Ni(4-pytpy)2]2+ with transition metals and different bridging ligands. All three compounds were characterized by elemental analysis, Fourier-transform infrared spectroscopy, thermal analysis and single-crystal X-ray diffraction analysis. Both CPs 1 and 2 display one-dimensional (1D) chain structures, which are further extended to 3D supramolecular structures through hydrogen bonds. CP-3 features a 2D network, which is constructed from 1D double chain cluster structure {[Cu3(SCN)5]2−}n linked by metalloligands [Ni(4-pytpy)2]2+ and exhibits an unusual (3,3,4)-connected 3-nodal topology. Thermal analysis indicates that the dehydrated structures of 1 and 3 can be stable up to 310xa0°C. The solid-state luminescence properties of compounds 1–3 were also investigated.