Synthesis and Crystal Structure of (L)2W(CO)4·CH3COCH3 (L = 1-Phenacylimidazole)

The reaction of 1-phenacylimidazole with W(CO)6 in a 1:1 molar ratio under irra- diation with a high-pressure Hg lamp mainly yielded the title compound (C29H26N4O7W, Mr = 726.39), which is of orthorhombic, space group Pbca with a = 27.665(4), b = 7.7807(12), c = 27.803(4) (A), V = 5984.8(16) (A)3, Z = 8, Dc = 1.612 g/cm3, λ(MoKα) = 0.71073 (A), μ = .3.911 mm-1, F(000) = 2864, R = 0.0583 and wR = 0.1502 for 3356 observed reflections (I > 2σ(I)). The crystal structural analysis indicates that in the coordination geometry of tungsten, 1-phenacylimidazole acts as a monodentate ligand and two imidazole ligands locate in a cis-position.     

Synthesis and crystal structure of [UO2(L)(OH)], (CN3H6)2[(UO2)2CrO4(L)4 · 2H2O and [UO2(H2O)5][(UO2)2Cr2O7(L)4] (where L is picolinate ion)

[[UO₂(L)(OH)] (I), (CN₃H₆)₂[(UO₂)₂CrO₄(L)₄] · 2H₂O (II), and [UO₂(H₂O)₅][(UO₂)₂Cr₂O₇(L)₄] (III) crystals, where L is picolinate ion C₅H₄NCOO^?, have been synthesized and studied by X-ray diffraction and IR spectroscopy. Complex I crystallizes in triclinic system with the unit cell parameters a = 6.2858(5) Å, b = 7.9522(5) Å, c = 8.3598(6) Å, α = 79.527(6)°, β = 87.760(6)°, γ = 79.126(6)°, space group P $\bar 1$ , Z = 2, R = 0.0306, and complexes II and III crystalize in monoclinic system with a = 8.8630(9) Å, b = 13.4540(13) Å, c = 31.266(3) Å, β = 93.118(3)°, space group C2/c, Z = 4, R = 0.0187 (II), and a = 7.3172(4) Å, b = 15.4719(8) Å, c = 16.6534(10) Å, β = 98.943(4)°, space group P2₁/m, Z = 2, R = 0.0588 (III). The structure of complex I is built of electronegative [UO₂(L)(OH)] chains, which belong to the AT¹¹M² crystallochemical group (A = UO ₂ ²⁺ , T¹¹ = L, M² = OH^?) of uranyl complexes. The structure of complexes II and III contains [(UO₂)₂(L′)(L)₄]^2? dimers (L′ = CrO ₄ ^2? or Cr₂O ₇ ^2? ), which belong to the A₂B²B ₄ ⁰¹ group (A = UO ₂ ²⁺ ,B² = L′, B⁰¹ = L). The specifics of intermolecular interactions in the structures of complexes I–III and some their analogues have been considered using molecular Voronoi-Dirichlet polyhedra.     

Synthesis and Crystal Structure of (L)_2W(CO)_4·CH_3COCH_3 (L=1-Phenacylimidazole)

1 INTRODUCTION Due to their variability in binding modes, five- membered heterocyclic ligands such as pyrazole[1] and 1,2,4-triazole[2] have been drawn much attention. Consequently, there are numerous reports on their derivatives. Imidazoles resemble pyrazoles, and they are isomeric five-membered heterocyclic molecules containing two nitrogen atoms. Furthermore, imida- zole is also a ring component of adenine and purine, one of the most versatile binding sites in biological systems, so th…     

Syntheses and structures of p-HOOCC6F4COOH · H2O (H2L · H2O) and luminescent coordination polymers [Tb2(H2O)4(L)3 · 2H2O] n and Tb2(Phen)2(L)3 · 2H2O

Compounds p-HOOCC₆F₄COOH · H₂O (H₂L · H₂O), [Tb₂(H₂O)₄(L)₃ · 2H₂O] _n (I), and Tb₂(Phen)₂(L)₃ · 2H₂O (II) are synthesized. According to the X-ray structure analysis data, the crystal structure of H₂L · H₂O is built of centrosymmetric molecules H₂L and molecules of water of crystallization. The crystal structure of compound I is built of layers of coordination 2D polymer [Tb₂(H₂O)₄(L)₃] _n and molecules of water of crystallization. The ligands are the L^2? anions performing both the tetradentate bridging and pentadentate bridging-chelating functions. The coordination polyhedron TbO₉ is a distorted three-capped trigonal prism. Acid H₂L manifests photoluminescence in the UV region (??_max = 368 nm). Compounds I and II have the green luminescence characteristic of the Tb³⁺ ions, and the band with ??_max = 545 nm (transition ⁵ D ₄?? ⁷ F ₅) is maximum in intensity. The photoluminescence intensity of compound II is higher than that for compound I.     

Ab initio study of Eu3+–L (L=H2O,H2S,NH2CH3, S(CH3)2, imidazole) complexes

The ground states and binding energies of Eu³⁺–L (L=H₂O,H₂S,NH₂CH₃,S(CH₃)₂, imidazole) complexes has been determined using ab initio techniques. The binding is mostly electrostatic as expected. The empty f orbital is different for the S compounds, being a π-like orbital, while for the O and N containing ligands it is a σ-like orbital. However, the range in the binding energies for the different f holes is small.     

Co(III) and Cr(III) complexes of diphosphadithia ligands and the crystal structure of [CoCl2(L3)]PF6·CH2Cl2 (L3=Ph2P(CH2)2S(o-C6H4)S(CH2)2PPh2)

[CrX₃(thf)₃] (X=Cl or Br) reacts with L (L=L¹–L³ or Ph₂[14]aneP₂S₂) (L¹=Ph₂P(CH₂)₂S(CH₂)₂S(CH₂)₂PPh₂, L²=Ph₂P(CH₂)₂S(CH₂)₃S(CH₂)₂PPh₂, L³=Ph₂P(CH₂)₂S(o-C₆H₄)S(CH₂)₂PPh₂, Ph₂[14]aneP₂S₂=4,8-diphenyl-1,11-dithia-4,8-diphosphacyclotetradecane) and TlPF₆ in MeNO₂ solution to yield the distorted octahedral complexes [CrX₂(L)]PF₆ as green coloured solids in high yield. UV/visible spectroscopy suggests that these are cis-dihalo species and they have also been characterised by IR spectroscopy, electrospray mass spectrometry and microanalyses. The Co(III) analogues [CoX₂(L)]⁺ are readily prepared in a two-stage reaction, involving treatment of CoX₂·6H₂O with L (L=L¹–L³) and NH₄PF₆ in EtOH solution to give a green/brown solid, followed by halogen oxidation of this product in CH₂Cl₂ solution using X₂/CCl₄, to give the final products as brown coloured solids. A mixture of PF₆⁻ and [CoX₄]²⁻ anions are present in the final Co(III) compounds in varying ratios. Crystal structures of [CoCl₂(L²)]₂[CoCl₄]·4H₂O and [CoCl₂(L³)]PF₆·CH₂Cl₂ confirm tetradentate P₂S₂ coordination of L in each case, with mutually cis halogens completing the distorted octahedral geometry. In both cases the complex cation adopts the cis-α form in the solid state and this is also consistent with the solution ³¹P{¹H} NMR spectroscopic data. ⁵⁹Co NMR spectroscopy reveals a very broad single resonance at ≈3200 ppm for these species.     

Complexes [Cu(H2L)](NO3)2 and [Cu(H2L)Cl]2[CuCl2]Cl · 0.5H2O (H2L is chiral bis(menthane) propylenediaminodioxime): Synthesis and structure

The synthesis of the [Cu(H₂L)](NO₃)₂ complex (I) and of a mixed-valent complex [Cu(H₂L)Cl]₂[CuCl₂]Cl·0.5H₂O (II), where L is chiral bis(menthane) propylenediaminodioxime. According to the data of single-crystal X-ray diffraction analysis, compounds I and II have ionic structures. In complex cations, the Cu²⁺ ion coordinates four N atoms of tetradentate chelate ligand, namely, the H₂L molecule. The coordination surrounding of the Cu atom in I is a distorted square CuN₄, while in II, it is a distorted square pyramid CuN₄Cl. The complex anion [CuCl₂]^? in II has linear structure. The mutual arrangement of oxime groups in H₂L corresponds to amphi-configuration of a ligand and therefore, intramolecular hydrogen bond O...H-O are formed in H₂L. The complex cations in compound II are joined in dimers through hydrogen bonds Cl...H-O. The values μ_eff for I and II are equal to 1.82 and 2.82 μ_B, respectively.     

The all non-metal homodinuclear and heterodinuclear sandwich-like compounds C2(η3-L3)2 and BN(η3-L3)2 (L = BCO, BNN and CBO)

Density functional theory studies on the all non-metal homodinuclear and heterodinuclear sandwich-like compounds C(2)(η(3)-L(3))(2) and BN(η(3)-L(3))(2) (L = BCO, BNN and CBO) have been performed. The staggered conformations of both C(2)(η(3)-L(3))(2) and BN(η(3)-L(3))(2) are predicted to be stable. The non-metal direct C-C and B-N bonds are covalent with σ interactions, which are formed by the interactions of s and p(z) orbitals of the center atoms. Different from the ionic metal-ligand bond in the traditional metal center sandwich-like compounds, the C-L, B-L, and N-L bonds are covalent in these all non-metal sandwich-like compounds. The NICS values indicate that the ligands of C(2)(η(3)-L(3))(2) and BN(η(3)-L(3))(2), as well as their bare rings, display multiple aromaticity (σ and π aromaticity). Both σ and π aromaticity of the ring ligands towards the center atoms become stronger after complexation with the center atoms, while the π aromaticity against the center atoms is reduced. The π aromaticity of the ligands bonded to different center atoms follows a trend of B > C > N, and the (CBO)(3)(+) ligands bonded to B possess the strongest π aromaticity. The dissociation reactions and possible synthetic reactions analysis show that these all non-metal sandwich-like compounds are stable, and the homodinuclear species are more stable than the heterodinuclear ones. These all non-metal binuclear sandwich-like compounds can be regarded as potential synthetic targets according to the highly negative free energies of the possible synthetic reactions. The isomerization reactions demonstrate that the CBO-based compounds should be more possible to synthesize in experiments than their BCO-based isomers.     

[Fe(L)3](ClO4)3(L=bpy,phen)与Na2S2O3在室温下的固相氧化还原反应

本文研究室温下[Fe(bpy)3](ClO4)3.3H2O和[Fe(phen)3](ClO4)3.H2O分别与Na2S2O3.5H2O发生的固-固相氧化还原反应。用Mossbauer谱、XRD、IR、UV漫反射谱、元素分析、TG-DTA和磁化率测定等手段表征了反应24h后的固相产物,报道了[Fe(bpy)3](ClO4)2的结晶学数据。结果表明, 室温下反应速度快, 反应进行完全。     

Electrochemical studies of the bis (triphenyl phosphine) ruthenium(II) complex,cis -[RuCl2(L)(PPh3)2], with L = 2-(2′-pyridyl)quinoxaline

Electrochemical studies of the newly synthesized bis(triphenyl phosphine) ruthenium(II) complex, cis-[RuCl₂(L)(PPh₃)₂] (1, with L = 2-(2′-pyridyl)quinoxaline, C₁₃N₃H₉), were performed in acetonitrile (ACN). For this purpose, cyclic voltammograms (CVs) as well as electrochemical impedance spectra (EIS) were recorded on either glassy carbon (GC), platinum (Pt), gold (Au), or multi-walled carbon nanotube (MWCNT) electrodes. Qualitative examination of solutions of 1 in ACN was performed on the basis of conductivity measurements and electrospray ionization mass spectrometry (ESI–MS). The conductivity data suggest that 1 is a 1 : 1 type electrolyte in ACN. The ESI spectra further demonstrate that upon dissolution of 1 in ACN progressive replacement of chloro- and PPh₃-ligands by ACN occurs, leading to formation of [RuCl(L)(PPh₃)(CH₃CN)₂]⁺Cl^?, [2 ⁺ Cl ^? ]. The CVs recorded for [2 ⁺ Cl ^? ] on various working electrodes demonstrate that the reversibility of the redox couple 2^{2 +/+} enhances with the order: Au < Pt < MWCNT < GC. The EI spectra verify that GC and MWCNT electrodes provide insignificant barrier for interfacial electron transfer since they afford less charge-transfer resistance.     

Crystal and molecular structure of dicopper bis-(3-amino-5-methylisoxazole)tetraacetate [Cu2(μ-OCOCH3)2L2]

It was established by X-ray diffraction analysis that in the dimer complex of 3-amino-5-methylisoxazole (L) [ Cu₂(μ-OCOCH₃)₄L₂ ] the coordination bond is localized at the endocyclic pyridine type N atom. Arguments are given against other possible types of coordination in aminoisoxazole complexes conjectured from IR spectroscopy data in a number of publications. The dimer structure of the complex agrees with antiferromagnetic data (2J = -280 cm^-1 ). Translated fromZhurnal Strukturnoi Khimii, Vol. 41, No. 3, pp. 572-580, May–June, 2000.     

A self assembled 3-D network propagated by coordination polymerization and H-bonding: synthesis and X-ray crystal structure of [{Co(L)2(H2O)2}(ClO4)2(CH3COCH3)2(H2O)2] n,where L = N,N-diisopropylisonicotinamide

Reaction of Co(ClO₄)₂?·?6H₂O with N,N-diisopropylisonicotinamide (L) has yielded a 1-D coordination polymer [{Co(L)₂(H₂O)₂}(ClO₄)₂(CH₃COCH₃)₂(H₂O)₂] _n (1). Complex 1 has been characterized by infrared (IR) and UV-Vis spectroscopies, thermal analysis, and single crystal X-ray diffraction techniques. The structure has alternate arrangement of parallel 1-D cationic metal-ligand chains and H-bonded anionic chains containing perchlorate, acetone and water in the lattice. Further hydrogen bonding among both chains leads to formation of 2-D networks along almost perpendicular planes. Interpenetrations of such perpendicular 2-D sheets create a 3-D supramolecular structure.     

Ru3(CO)9(PPh3)3: a convenient starting material for the synthesis of binuclear ruthenium(I) complexes. Crystal structure of Ru2(μ-L2)(CO)4(PPh3)2 (H2L2 = 1,8-diaminonaphthalene)

The thermal reaction of Ru₃(CO)₉(PPh₃)₃ with precursors (HL) of binucleating anionic ligands affords the ruthenium(I) dimers Ru₂(μ-L)₂(CO)₄(PPh₃)₂ (3), t-butylmercaptane (4); H₂L₂ = 1,8-diaminonaphthalenene (5)]. The crystal structure of complex 5 shows that each nitrogen of the 1,8-diiminonaphthalene ligand bridges the two ruthenium atoms, leading to a vary distorted, octahedral arrangement of the ligands and a very short RuRu distance, 2.5788(3) Å.     

The quadruply bondedbis-carboxylatescis-Re2(μ-O2CCH3)2X4L2 (X = halide;L = neutral donor) as synthons in dirhenium chemistry

The reactions of the quadruply bonded dirhenium(III) carboxylatescis-Re₂(-O₂CR)₂X₄L₂ (X=CI or Br; L=a monodentate donor) with monodentate, bidentate, and tridentate phosphine donors result in several types of redox behavior, usually involving partial or complete reductive decarboxylation of the dirhenium unit. Examples of dirhenium(VI, II), dirhenium(IV, II), dirhenium(III, II), and dirhenium(II, II) complexes, in which Re-Re bond orders of 4, 3.5, 3, l, or zero are encountered, have been isolated and repre-sentative examples structurally characterized. The course of these reactions is dependent upon the nature of the phosphine. The scope of this remarkably rich chemistry is discussed.     

Synthesis,crystal structures and magnetism of lanthanide(III) binuclear complexes [Ln2(μ1 ,3-CH3CO2)2(SCN−)4L2(H2O)6] (Ln = Gd(III) and Eu(III), L = 4-methylpyridine N-oxide)

Two lanthanide(III) binuclear complexes have been synthesized with acetate as bridging ligand and 4-methylpyridine N-oxide (L), SCN^? and H₂O as terminal ligands and structurally determined by X-ray crystallography. Both crystals [Gd₂(μ_1,3-CH₃CO₂)₂(SCN^?)₄(L)₂(H₂O₆) (1) and [Eu₂(μ_1,3-CH₃CO₂)₂(SCN^?)₄(L)₂(H₂O)₆] (2) belong to monoclinic with space group P2₁/n. The relevant cell parameters are as follows: a?=?9.0034(12)?Å, b?=?15.998(2)?Å, c?=?12.1277(17)?Å, β?=?100.625(2)° for complex 1; and a?=?9.0168(18)?Å, b?=?15.990(3)?Å, c?=?12.142(2)?Å, β?=?100.734(3)° for complex 2; The two lanthanide(III) ions are bridged by two acetate anions forming a binuclear unit, in which L, SCN^? and H₂O as unidentate terminal ligands take part in the coordination. The variable-temperature magnetic susceptibility of 1 was measured in the 4–300?K range; fitting for the susceptibility data reveals that there is no magnetic interaction between the bridged Gd(III) ions.     

Tansition metal complexes with 2-(1-(carboxymethyl)-2-methyl-1H-benzimidazol-3-ium-3-yl)acetate (HL): Synthesis and crystal structure of [Co(L)2(H2O)4] · 6H2O and [Cu(L)2(H2O)2] · 4H2O

Transition metal complexes of 2-(1-(carboxymethyl)-2-methyl-1H-benzimidazol-3-ium-3-yl)acetate (HL), namely [Co(L)₂(H₂O)₄] · 6H₂O (I) and [Cu(L)₂(H₂O)₂] · 4H₂O (II), have been synthesized by a hydrothermal procedure and characterized by X-ray crystallography, CIF files CCDC nos. 1007524 (I), 1007525 (II). Both I and II are mononuclear molecules. In I, the Co²⁺ ion is in octahedral coordiantion environment and surrounded by four O atoms from water molecules and two carboxylate O atoms of two deprotonated ligand (L^?) occupied six culmination. While in II, the Cu²⁺ ion is located in a square-planar geometry, bounded to two aqua O atoms and two carboxylate O atoms from L^?.     

Dinuclear copper(II) complexes with ferromagnetic and antiferromagnetic interactions mediated by a bridging oxalato group: structures and magnetic properties of [Cu2L4(μ-C2O4)](PF6)2(H2O)2 and [Cu2L2(μ-C2O4)(NO3)2((CH3)2NCOH)2] (L = di-2-pyridylamine)

Two dinuclear Cu^II complexes of formula [Cu₂(dpyam)₄(μ-C₂O₄)](PF₆)₂(H₂O)₂ (1) and [Cu₂(dpyam)₂(μ-C₂O₄)(NO₃)₂(DMF)₂] (2) (dpyam=di-2-pyridylamine) have been synthesized and their spectroscopic and magnetic properties characterized. Complex (1) crystallizes in the non-centrosymmetric monoclinic space group Pc, while (2) crystallizes in the non-centrosymmetric triclinic space group P1. Compound (1) involves the compressed octahedral Cu^II environment, whereas (2) exhibits an elongated octahedral Cu^II geometry. Both complexes contain six-coordinate metal centers bridged by planar bis-didentate oxalate group. The geometry, spectroscopic properties and the effective magnetic moment of (1) are very close to those of the recently published [Cu₂(dpyam)₄ (μ-C₂O₄)](ClO₄)₂(H₂O)₃ and [Cu₂(dpyam)₄(μ-C₂O₄)](BF₄)₂(H₂O)₃. Thus (1) is expected to exhibit a very weak ferromagnetic interaction between the Cu^II centers which is confirmed by EPR spectrum. Those of (2) are comparable to those of the recently published [Cu₂(dpyam)₂(μ-C₂O₄)(NO₃)₂(DMSO)₂]. Therefore a strong antiferomagnetic interaction is expected. The effective magnetic moment at room temperature of (1) was measured to be 2.55 BM/dimer, which agrees with the spin only value of Cu^II, 2.45BM calculated for two uncoupled spin=1/2 centers. In (2) the room temperature effective magnetic moment of 2.16 BM/dimer indicates the partial spin paring by antiferromagnetic coupling. This is confirmed by the e.p.r. spectrum and is explained as a result of the magnetic interaction between the coplanar ${\rm d}_{x^2-y^2}$ orbitals on the two copper atoms.     

The coordination chemistry of mono and bis(di-2-pyridylamine)copper(II) complexes: preparation,characterization and crystal structures of [Cu(L)(NO2)2], [Cu(L)(H2O)2(SO4)], [Cu(L)2(NCS)](SCN)·0.5DMSO and [Cu(L)2(SCN)2]

The crystal structures of two mono(dpyam)copper(II) complexes, [Cu(dpyam)(NO₂)₂] (1) and [Cu(dpyam)(H₂O)₂(SO₄)] (2) and two dithiocyanate compounds containing bis(dpyam)copper(II) units, [Cu(dpyam)₂(NCS)](SCN)·0.5DMSO (3) and [Cu(dpyam)₂(SCN)₂] (4) have been determined by X-ray crystallography. The second orthorhombic form of the monomeric Cu(II) complex 1 was obtained by the reaction of di-2-pyridylamine (dpyam) with CuCl and NaNO₂ in water–methanol solution. Each copper(II) ion in 1 exhibits a tetrahedrally-distorted square base of the CuN₂O₂ chromophore, with off-the-z-axis coordinated nitrito groups weakly bound in approximately axial positions. Complex 2 is an example of a polymeric copper(II) derivative containing the bidentate bridging sulfate ligand in the long-bonded axial positions. Each copper(II) ion in 2 shows an elongated tetragonal octahedral stereochemistry. The CuN₄N′ chromophore of 3 involves a square-based pyramidal structure, slightly distorted towards a trigonal bipyramidal stereochemistry, τ=0.13. One of the SCN⁻ anions is bonded to the copper(II) ion via the N atom in the axial position of the square pyramid. Complex 4 is centrosymmetric and octahedrally elongated, with the SCN⁻ anions coordinating in axial positions via the S atom. The structures of complexes 1–4 and their ESR and electronic reflectance spectra are compared with those of related complexes.     

1,2,4-Triphospholyl gold(I) and copper(I) complexes: synthesis,crystal and molecular structures of [Cu(PMe3)2(μ-P3C2tBu2)(μ-I)Cu(PMe3)2], [Cu(PMe3)2(μ-P3C2tBu2)2Cu(PMe3)2] and [Au(η1-P3C2tBu2)2][Au(PEt3)2]

Treatment of K(P₃C₂^tBu₂) with Cu₂I₂ and PMe₃ gave the binuclear complex [Cu(PMe₃)₂(μ-P₃C₂^tBu₂)₂Cu(PMe₃)₂] via the isolated intermediate compound [Cu(PMe₃)₂(μ-P₃C₂^tBu₂)(μ-I)Cu(PMe₃)₂]. The reaction of K(P₃C₂^tBu₂) with [AuCl(PEt₃)] on the otherhand gave the cation:anion complex [Au(PEt₃)₂][Au(η¹-P₃C₂^tBu₂)₂]. All complexes were fully characterised by multinuclear spectroscopy and single crystal X-ray diffraction studies.