Preparation and study of cyclic polynuclear ferrocenes derived from (C6H5)2PCH2CH2Si(CH3)2C5H4Li as a bridging ligand

The synthesis of the potential bridging ligand (C₆H₅)₂PCH₂CH₂Si(CH₃)₂C₅H₄ (3) is described. The ferrocene (6 derived from 3 has been found to form macrocyclic complexes with metal fragments NiCl₂, NiBr₂, and Co₂(CO)₆. Although monomeric, bimetallic products might have been expected based upon the reduced steric demands of ligand 3 relative to an analogous ligand, (C₆H₅)₂PCH₂Si(CH)₃)₂C₅H₄ (1), it appears that the increased flexibility in 3 is the overriding factor leading to a preference for inter- rather than intramolecular coordination of the second phosphine function in 6.     

Ligand close packing and the geometries of A(XY)4 and some related molecules

Molecules of the type A(OX)₄, A(NX₂)₄ and A(CY₂X)₄ are not regularly tetrahedral about the central atom A. Two of the angles about this central atom are smaller than tetrahedral and four are larger, or four are smaller and two larger. By considering that the ligand atom (O, N or C) that is bonded to the central atom A has three intramolecular ligand radii and minimising the number of ligand–ligand contact distances, as described in the theory of ligand close packing, we are able to account for the S₄ and D_2d geometries observed for C(OCH₃)₄, C(OPh)₄ and CEE₄ and related molecules. The ligand close packing model also rationalises the C₂ geometries of SO₂(OR)₂ molecules and the differences in O–C–R angles and C–R bond lengths in R₃COX molecules. The lengths of these interligand radii can be determined either by calculating the molecular geometry or by deriving them from experimental geometries. The radii depend on the charge of the ligand, the sizes of the Y and Z groups and the angle A–X–Z. The relative sizes of these radii determine the preference for D_2d or S₄ geometries and the degree of distortion of the bond angles from the ideal tetrahedral angle.     

Dinuclear transition metal compounds of a decadentate pyrazole-containing chelating ligand. X-ray crystal structure of Co2(tthd)(ClO4)4(H2O)2(MeOH)1.75

A potentially decadentate ligand, 1,1,4,7,10,10-hexakis(3,5-dimethyl-1-pyrazolylmethyl)-1,4,7,10-tetraazadecane (tthd), has been synthesized from the reaction of tri-ethylenetetramine with six equivalents of N-hydroxymethyl-3,5-dimethylpyrazole. The tthd ligand forms coordination compounds, M₂(tthd)(ClO₄)₄(H₂O)_x, when M is Co, Ni, Cu, Zn and Cd and x = 4–8; and M₂(tthd)(A)₂(ClO₄)₂(H₂O)_x when M is Co and Ni, A is NCS or Cl, and x = 4–8. The cobalt compound, Co₂(tthd)(ClO₄)₂(H₂O)₂(MeOH)_1.75, crystallizes in the triclinic space group P1, a = 1.959(2), b = 1.5657(3), c = 2.1244(3) nm, = 105.5(1), β = 96.9(1), γ = 112.1(1). Due to severe disorder of the anions the structure could only be refined to an R_w, value of 0.099. The ligand acts as a decadentate, dinucleating ligand. The cobalt ions are distorted octahedrally surrounded by five N-atoms of the tthd ligand and an O-atom of water occupying the sixth coordination place. The other perchlorate compounds have very similar structures, as can be concluded from spectroscopic data.

In the thiocyanate and chloride compounds the anions have replaced the coordinated water molecules, resulting in octahedral Ni compounds. With Co thiocyanate, however, tthd acts as an octadentate ligand, resulting only in five-coordinated compounds.     

Complex formations of silver(I) trifluoroacetate and trifluoromethanesulfonate with benzene and cyclohexene

An apparatus for measurements of equilibrium ligand vapor pressure has been applied in order to determine the stoichiometry of benzene and cyclohexene complexes of silver(I) trifluoroacetate (AgCF₃CO₂) and silver(I) trifluoromethanesulfonate (silver(I) triflate, AgCF₃SO₃) in the solid state. It has been found that the equilibrium leads the formation of such complexes as: (AgCF₃CO₂)₂(C₆H₆), (AgCF₃CO₂)₂(C₆H₁₀), (AgCF₃CO₂)₂(C₆H₁₀)₃, (AgCF₃SO₃)₂(C₆H₆), (AgCF₃SO₃)(C₆H₆), (AgCF₃SO₃)(C₆H₁₀) and (AgCF₃SO₃)(C₆H₁₀)₂. The temperature dependence of the gas-solid equilibrium ligand pressure has also been examined for these complexes, and the enthalpy and entropy changes according to the following complex dissociation reactions were estimated: (AgCF₃CO₂)L_m (s) AgCF₃CO₂ (s)+mL (g): and (AgCF₃SO₃)L_n (s) AgCF₃SO₃ (s)+nL (g), where L's are benzene and cyclohexene. On the basis of the thermodynamic data obtained, the effects of the counter anion as well as the ligand on the complex stability are discussed.     

A new dirbenium complex with an unsupported bridging hydride ligand

The reaction of Re₂(CO)₈(μ-H)2 with CH₂(NMe₂)₂ in chloroform at 25°C yielded the new compound Re₂(CO)₈(NHMe₂)(Cl)(μ-H) (1) in 31% yield. Compound 1 was characterized by IR, ¹H NMR and a single-crystal X-ray diffraction analysis. Crystal data: orthorhombic, Pbca, a = 13.787(4), b = 19.884(5), c = 12.296(2) Å. Solution by direct methods (MITHRIL), R = 0.035 for 1800 reflections. The complex contains two rhenium atoms linked by an unsupported hydride bridge, Re Re = 3.362(1) Å, Re(1)---H = 1.8(1) Å and Re(2)---H = 2.0(1) Å. A chloride ligand abstracted from the solvent is terminally bonded to Re(1), and a dimethylamine ligand abstracted from the CH₂(NMe₂)₂ is coordinated to Re(2). When heated to 68°C, the dimethylamine ligand was eliminated and the chloride ligand became a bridge in the new compound Re₂(CO)₈(μ-H)(μ-Cl) (2), yield 76%.     

三核铁苯甲酸配合物[Fe3O(OBz)6(CH3OH)3](NO3)(CH3OH)2的电子光谱及其理论分析

测定了三核苯甲酸铁配合物[Fe₃O(OBz)₆(CH₃OH)₃](NO₃)(CH₃OH)₂(OBz^-=苯甲酸根)的电子光谱,应用配体场理论和T-S图求得配体场参数10Dq=12457cm^-1.用CNDO/2方法对其简化模型进行了计算。     

Dimethylaluminum and gallium amino alkoxides

An S,S′-thioether—thioester chelating ligand [7,8-μ-SCH₂C(O)S-7,8-C₂B₉H₁₀]⁻ (L₁), incorporating the unit [—(C)₂B₉H₁₀]⁻ has been synthesized. Reactions have been conducted with RhCl(PPh₃)₃ and PdCl₂(PPh₃)₂ complexes in ethanol. With Rh, L₁ maintains its original cyclic nature and most probably chelation via thioether—thioester takes place. The carborane negative charge may stabilize this original thioether—thioester complex. The other two Rh positions are occupied by two PPh₃ ancillary ligands forming [Rh(L₁)(PPh₃)₂]. The reaction of L₁ with Pd induces ligand modifications and the cyclic nature of L₁ is lost. A transesterification process leading to a dianionic ligand L₂, [7-S-8-SCH₂C(O)OCH₂CH₃−7,8-C₂B₉H₁₀]²⁻ has taken place. In this way L₂ is capable of compensating the dipositive Pd charge. The other two Pd positions are occupied by two PPh₃. This reaction has been extended to methanol and isopropanol solvents. The crystal structure of [Pd(L₂)(PPh₃)₂] has been determined.     

Synthesis and structure of ansa-cyclopentadienyl pyrrolyl titanium complexes: [(η-C5H4)CH2(2-C4H3N)]Ti(NMe2)2 and [1,3-{CH2(2-C4H3N)}2(η-C5H3)]Ti(NMe2)

Reaction of ansa-cyclopentadienyl pyrrolyl ligand (C₅H₅)CH₂(2-C₄H₃NH) (2) with Ti(NMe₂)₄ affords bis(dimethylamido)titanium complex [(η⁵-C₅H₄)CH₂(2-C₄H₃N)]Ti(NMe₂)₂ (3) via amine elimination. A cyclopentadiene ligand with two pendant pyrrolyl arms, a mixture of 1,3- and 1,4-{CH₂(2-C₄H₃NH)}₂C₅H₄ (4), undergoes an analogous reaction with Ti(NMe₂)₄ to give [1,3-{CH₂(2-C₄H₃N)}₂(η⁵-C₅H₃)]Ti(NMe₂) (5). Molecular structures of 3 and 5 have been determined by single crystal X-ray diffraction studies.     

Übergangsmetall-Carbin-Komplexe LXXXVII. Synthese neuer, thermisch stabiler, kationischer Diethylaminocarbin-Komplexes des wolframs

trans-I(CO)₂L₂WCNEt₂ complexes (L₂ = 2,2′-bipyridyl (2,2′-bipy); 1,10-phenanthroline (ophen)) react with PR₃ (R = Me, Et) and thus undergo substitution of the iodine ligand by the phosphine to yield the new, thermostable, cationic carbyne complexes, [(PR₃)(CO)₂L₂WCNEt₂]⁺ I⁻. The ionic character of the compounds has been established from electrical conductivity studies of their solutions. Spectroscopic investigations of the complexes, whose composition has been determined by elemental analysis, indicate that in this reaction the halogen ligand in the trans position has been displaced by the chelate ligand, while the phosphine ligand occupies a cis coordination site, relative to carbyne moiety.     

Reaction of the tetrasulphidomolybdenum(IV) complex LMo(NCS)(S4) with dicarbomethoxyacetylene: X-ray structure of LMo(NCS){S2C2(CO2Me)2} [L = hydrotris(3,5-dimethylpyrazolyl)borate]

The reaction of {HB(Me₂pz)₃}Mo(NCS)(S₄) [HB(Me₂pz)₃⁻ = hydrotris(3,5-dimethylpyrazolyl)borate anion] with dicarbomethoxyacetylene in refluxing toluene results in the formation of the brown, diamagnetic complex {HB(Me₂pz)₃}Mo(NCS){S₂C₂(CO₂Me)₂} (1) (the reactants above also yield 1 upon prolonged reaction in dichloromethane at 25°C), which has been characterized by X-ray crystallography. The mononuclear pseudo-octahedral complex contains a facially tridentate HB(Me₂pz)₃⁻ ligand, a monodentate N-bound NCS⁻ ligand, and a bidentate S₂C₂(CO₂Me)₂²⁻ ligand having a near planar MoS₂C₄ fragment and a SC=CS bond distance of 1.342(15) Å. Solutions of 1 are unstable in air and decompose to produce {HB(Me₂pz)₃}MoO₂(NCS) and {HB(Me₂pz)₃}MoO(NCS)₂.     

Synthesis and Bioactivity of a Novel Bismuthoxide Schiff-base Complex Derived from Salen-like Ligand and Bismuth(Ⅲ) Nitrate

In this paper, a novel bismuthoxide Schiff-base complex [Bi₉O₈(vanen)₃(NO₃)₂(CH₃OH)₂(H₂O)·3NO₃·5.5H₂O](abbreviated as Bivanen) was synthesized with Salen-like ligand H₂vanen[H₂vanen=N,N'-ethylene bis(3-methoxysalicylideneimine)] and bismuth(Ⅲ) nitrate. Its structure was characterized by IR spectra, NMR spectra and X-ray diffraction. In particular, the biology activities of the ligand and the complex against Schizosaccharomyces pombe(S. pombe) were studied using biological microcalorimetry. The metabolic thermogenic curves of S. pombe were measured at 32.00℃. Then, some quantitative thermokinetic parameters of growth metabolism of S. pombe including the rate constant(k), inhibition ratio(I) and half inhibition concentration(IC₅₀) were calculated. Experimental results showed that the k values of S. pombe decreased while I values of S. pombe increased with the increase of concentrations of the ligand and the complex. The IC₅₀ of the ligand and the complex were found to be 0.067 and 0.037 mmol/L, respectively.     

Structural tuning of coordination polymers by 4-connecting metal node and secondary building process

Due to variation in ligand's conformation, metal node's connecting geometry, and secondary building process by anions, bat-like, dumbell-like, diamondoid, or pillar-layer topologies are achieved.     

A new route to complexes containing the tetracarbon (C4) ligand

Pyrolysis of a solution of {Ru₃(CO)₁₁}₂(μ-bdpp) (bdpp = bis(diphenylphosphino)butadiyne) yielded the complex {Ru₃(μ-PPh₂)(CO)₉}₂(μ₆-C₄), which contains a μ₆-C₄ ligand symmetrically bridging two Ru₃(μ-PPh₂)(CO)₉ clusters. When the complex {Fe(CO)₄}₂(μ-bdpp) was heated in the presence of Fe₂(CO)₉ another example of a C₄ complex, {Fe₂(μ-PPh₂)(CO)₆}₂(μ-C₄), was obtained. Both complexes were characterised by X-ray structure determinations; the C₄ ligand behaves as a buta-1,3-diyne-1,4-diyl system.     

The electrochemical reduction of CP2TiCl2 in the presence of trimethylphosphine

The electrochemistry of the complexes Cp₂TiCl_x(PMe₃)_2-x in anhydrous THF has been studied. The most stable complexes at the three oxidation states of titanium are Cp₂TiCl₂, Cp₂TiCl(PMe₃) and Cp₂Ti(PMe₃)₂, and each of these species is readily formed by electrolysis. It has also been demonstrated that oxidation/reduction of these species is followed by facile and rapid ligand exchange to form the preferred species in the new oxidation state provided a stoichiometric concentration of the required ligand is present. The consequences of this redox and ligand exchange chemistry for the synthetic reactions catalyzed by lower oxidation states of Ti are discussed. Finally, the voltammetry of a titanocycle is reported, and it is shown that the corresponding Ti^III metallocycle is stable.     

噻吩醛缩乙二胺席夫碱及其配合物的合成与光催化性能

基于TiO₂光催化性能的染料敏化改性,采用2-噻吩甲醛缩合乙二胺合成了席夫碱配体L,并与金属配合得到了金属配合物[ZnLCl₂](1),[NiL'(NO₃)₂](2)(L'为单噻吩醛缩乙二胺),对配体L、配合物1 和2进行了X射线单晶衍射结构分析。 用合成的配体和配合物修饰TiO₂得到相应的复合光催化剂L-TiO₂、1-TiO₂和2-TiO₂,并进行了红外光谱、紫外-可见漫反射光谱、粉末X射线衍射图谱等表征,研究了这3种光催化剂降解水中有机污染物4-硝基酚(4-NP)和罗丹明B(RhB)的催化活性。 结果表明,1-TiO₂、2-TiO₂可以有效的降解4-NP和RhB,降解率可达90%以上。     

Crystal structure and luminescence property of ternary terbium p-aminobenzoic acid complexes with different second ligands

Ternary terbium complexes with p-aminobenzoic acid (HL), [TbL₃(DMSO)(H₂O)]₂ (1), [TbL₃(DMF)(H₂O)]₂ (2) and [TbL₃(Bpy)(H₂O)]₂·2H₂O (3) (DMSO=dimethyl sulfoxide, DMF=N, N- dimethylformamide, Bpy=2, 2′- bipyridyl) have been synthesized, and their crystal structures determined. The luminescence properties of these complexes, including both the emission quantum yield and the fluorescence lifetime, have been investigated. The effect of a second ligand on the crystal structure and luminescence property of the ternary terbium p-aminobenzoic acid complexes, and the relationship between luminescence properties and crystal structure, including coordination mode of the L⁻ ligand and the characteristics of a second ligand, are discussed.     

有机膦溴化钯(Ⅱ)配合物的合成、结构及其催化偶联反应活性

以PdBr2为起始原料,分别选择二叔丁基苯基膦((t-Bu)2PPh)、二叔丁基-(4-二甲基氨基苯基)膦(Amphos)、4,5-双二苯基膦-9,9-二甲基氧杂蒽(Xantphos)为有机膦配体,通过溶剂的配位加成和有机膦的配位取代,合成出3种溴化钯配合物,以寻找性能更佳的偶联催化剂.借助元素分析仪、核磁共振仪及单晶...     

Multiple ligand transfer reaction between [CpRu(L)(AN)2][PF6] (L=AN, CO, P(OMe)3; AN=acetonitrile) and CpFe(CO)L′X (L′=CO, PMe3, PMe2Ph, PMePh2, PPh3, P(OPh)3; X=Cl, Br, I)

Treatment of ruthenium complexes [CpRu(AN)₃][PF₆] (1a) (AN=acetonitrile) with iron complexes CpFe(CO)₂X (2a–2c) (X=Cl, Br, I) and CpFe(CO)L′X (6a–6g) (L′=PMe₃, PMe₂Ph, PMePh₂, PPh₃, P(OPh)₃; X=Cl, Br, I) in refluxing CH₂Cl₂ for 3 h results in a triple ligand transfer reaction from iron to ruthenium to give stable ruthenium complexes CpRu(CO)₂X (3a–3c) (X=Cl, Br, I) and CpRu(CO)L′X (7a–7g) (L′=PMe₃, PMe₂Ph, PMePh₂, PPh₃, P(OPh)₃; X=Br, I), respectively. Similar reaction of [CpRu(L)(AN)₂][PF₆] (1b: L=CO, 1c: P(OMe)₃) causes double ligand transfer to yield complexes 3a–3c and 7a–7h. Halide on iron, CO on iron or ruthenium, and two acetonitrile ligands on ruthenium are essential for the present ligand transfer reaction. The dinuclear ruthenium complex 11a [CpRu(CO)(μ-I)]₂ was isolated from the reaction of 1a with 6a at 0°C. Complex 11a slowly decomposes in CH₂Cl₂ at room temperature to give 3a, and transforms into 7a by the reaction with PMe₃.     

Oxidative addition reactions in cluster complexes of osmium: Intracluster reactions of benzyne and a novel 'phenyl' complex

The structures of HOs₃(CO)₇(PPh₂)(PPh₃)(C₆H₄), HOs₃(CO)₈(PPh₃)(PPh₂C₆H₄) and HOs₃(CO)₇(PPh₂)(PPh₂C₆H₄C₆H₃) are described, the latter illustrating an intracluster reaction of the coordinated benzyne ligand.     

利用还原取代反应合成双核铜(Ⅰ)配合物及其晶体结构研究

铜(Ⅰ)配合物由于其变化奇异的结构、性质及配位数而引起化学工作者的广泛兴趣.四电子供体双二苯基膦甲烷(dppm)适宜在近距离内与2个金属原子同时配位,容易形成八元环的二聚体M₂P₄C₂,因而是桥联2个低氧化态过渡金属的最佳选择.