One 3D and one 2D μ1,5-dicyanamide bridged NiII complexes having molecular formula [Ni(L1)(dca)2] (1) and [Ni2(L2)2(dca)4] · 0.5H2O (2) (L1 = 4-(2-aminoethyl)-morpholine, L2 = 1-(2-aminoethyl)-piperidine and dca = dicyanamide dianion) have been synthesized. X-ray single crystal analyses and low temperature magnetic measurements were used to characterize the complexes. Complex 1 represents a 3D structure where each metal ion is chelated by morpholine ligand (L1) and connected by four μ1,5-dca. Whereas complex 2 shows an undulated 2D structure with grid of (4,4) topology having two crystallographically independent NiII centers in similar octahedral environment where each metal center is chelated by one piperidine ligand (L2) and coordinated by four μ1,5-dca. Magnetic measurements of both the complexes indicate weak antiferromagnetic interactions through the μ-1,5-dca bridging ligands. 相似文献
Two hexacoordinated dinuclear compounds [Mn(L1)(dca)]2(ClO4/PF6)2·CH3OH (1/2) and two heptacoordinated coordination polymers [Mn(L2)(dca)]n(ClO4/PF6)n (3/4) [L1 = N,N′-(bis-(pyridin-2-yl)benzylidene)-1,3-propanediamine; L2 = N,N′-(bis-(pyridin-2-yl)benzylidene)diethylenetriamine; dca = dicyanamide] are synthesized and characterized. Structures of 1-3 have been solved by X-ray diffraction measurements. Each manganese(II) center in 1/2 is located in a distorted octahedral environment with an MnN6 chromophore coordinated by the four N atoms of L1 and two nitrile N atoms of bibridged μ1,5 dca. Interestingly, the coordination polymer 3 forms a 1D chain through single Mn-(NCNCN)-Mn units in which each manganese(II) center adopts a pentagonal bipyramidal geometry with an MnN7 chromophore occupied with five N atoms of L2 and two nitrile N atoms of monobridged μ1,5 dca. Magnetic susceptibility measurements of 1-3 in the 2-300 K temperature range reveal weak antiferromagnetic interactions. 相似文献
A topological analysis based on density functional electronic and spin densities of the bonding characteristics in a series of Fe, Ru, Os, Tc and Rh dimers and trimers bridged, respectively, by μ-1,8-naphthyridine (nap) and μ-2,2′-dipyridylamine (dpa) is presented. By this simple qualitative analysis, we were able to determine the electronic ground state and correlated bonding order for a number of complexes potentially involved in extended metal atom chains (EMAC). Furthermore, we showed in the Ru dimer that it was possible to control the spin state simply by changing the bonded counter-anion.
The thermal reaction of Ru3(CO)12 with the biologically active acids acetyl salicylic acid (Aspirin), α-methyl-4-(isobutyl)phenylacetic acid (Ibuprofen) and 3α,7α,12α-trihydroxy-5β-cholanic acid (cholic acid) in refluxing tetrahydrofuran, followed by addition of triphenylphosphine, gives the dinuclear complexes Ru2(CO)4(OOCR)2(PPh3)2 (1: R = C6H4-2-OCOMe, 2: R = CHMe-C6H4-4-Bui, 3: C23H39O3). The single-crystal structural analysis of 1 and 2 reveals a dinuclear Ru2(CO)4 sawhorse structure, the diruthenium backbone being bridged by the carboxylato ligands, while the two phosphine ligands occupy the axial positions at the ruthenium atoms. However, chiral carbon atoms in the carboxylic acid undergo racemisation during the thermal reaction. 相似文献
The cationic carbyne complex [Cp(CO)2MnCC6H5]BBr4 (1) reacts with PPN[Rh(CO)4] (2) to give the title cluster [(μ3-CC6H5)(μ-CC6H5) Rh2Mn2Cp2(μ-CO)3(CO)3] (3) whose structure has been determined by X-ray diffraction. The electrochemical properties of 3 have been investigated using cyclic voltammetric method. At 60 °C and 2.0 MPa of initial total CO/H2 (1:1) pressure, the catalytic activity of 3 towards hydroformylation of styrene has also been checked. 相似文献
The one pot aqueous reaction of M(ClO4)2 (M = Cu2+ or Ni2+) with N-methylbis[2-(2-pyridylethyl)]amine (MeDEPA) and N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)ethylenediamine (bpmen) and 1,4,7,10-tetraazacyclododecane (cyclen) in presence of sodium dicyanamide (Nadca) yielded dicyanamido-bridged polynuclear complex {[Cu(MeDEPA)(μ-1,5-dca)]ClO4}n (1), and two dinuclear complexes [Cu2(bpmen)2(μ-1,5-dca)]2(ClO4)5dca (2) and [Ni(cyclen)(μ-1,5-dca)]2(ClO4)2 (3). These complexes were characterized by IR and UV-Vis spectroscopy. Room temperature single-crystal X-ray studies have confirmed that the Cu(II) centers in 1 and 2 adopt geometries that are more close to trigonal bipyramidal (TBP) in 1 and close to square pyramidal (SP) in 2, whereas in 3, the Ni(II) centers are located in octahedral environment with doubly bridged μ-1,5-dca bonding mode. The intermolecular M···M distances in these complexes are in the range of 7.3-8.6 Å. Variable temperature magnetic susceptibility studies have confirmed that the dca-bridges mediate very weak antiferromagnetic interaction between the M(II) centers with J values of −0.35, −0.18 and −0.43 cm−1 for 1, 2 and 3, respectively. The results are compared and discussed in the light of other related bridged μ-1,5-dca Cu(II) and Ni(II) complexes. 相似文献
Two new Zn(II) complexes, [Zn(dap)Cl2] (1) and [Zn(dap)2Cl2] (2) (dap stands for 2,3-diaminopyridine), were prepared and spectroscopically and crystallographically characterized. In both compounds, the zinc(II) atom has a pseudo-tetrahedral ZnN2Cl2 coordination environment. Compound 1 adopts a three-dimensional structure built up from [Zn(dap)Cl2]n zig-zag chains, which are linked by N-H?Cl hydrogen bonds. In compound 2 the dap is monodentate coordinating via the pyridine nitrogen; the mononuclear tetrahedral [Zn(dap)2Cl2] units are linked into two-dimensional sheets through extensive N-H?Cl hydrogen bonding. Inter-sheet π-π interactions connect them into a three-dimensional network. 相似文献
The synthesis and characterization of the pyrazine-bridged tweezer complex [{[Ti](CCSiMe3)2}Ag(OClO3)]2pz (4) and bimetallic {[Ti](CCSiMe3)2}Ag(OClO3)(pz) (3) {[Ti]=(η5-C5H4SiMe3)2-Ti; pz=1,4-pyrazine, C4H4N2} is discussed. The solid-state structure of 4 is reported. The structure of 4 consists of two heterobimetallic titanium-silver tweezer fragments of type {[Ti](μ-σ, π-CCSiMe3)2}Ag(OClO3) which are spanned by pyrazine. Each silver(I) ion is thereby tetra-coordinated by two π-coordinated alkynes and the datively bound pyrazine and OClO3 moieties. Cyclic voltammetric studies of 3 and 4 are reported. 相似文献
A novel tetranuclear μ3,η3- Cu(II) complex with a new coordination mode of a hydrogenphosphato bridge, [Cu4(di-2-pyridylamine)4(μ3,η3-HPO4)2(H2O)2(NO3)2](NO3)2(H2O)2 has been synthesised and characterised structurally, spectroscopically and magnetically. The geometry around the Cu(II) ions is distorted square pyramidal for Cu(1) and an intermediate between square pyramidal and trigonal pyramidal. The magnetic susceptibility measurements have been fit for a weak antiferromagnetic interaction of J = −10.3(1) cm−1 between outer Cu ions and J = −5.3(2) cm−1 between inner Cu atoms. 相似文献
The novel polynuclear [{Ru3O(CH3COO)6(py)2}2(BPEB)](PF6)2 species containing the linear bridging trans-1,4-bis[2-(4-pyridyl)ethenyl]-benzene ligand (BPEB) was synthesized and its structural characterization carried out by means of positive ion electrospray (ESI-MS) and tandem mass (ESI-MS/MS) spectrometry, as well as by 1H NMR spectroscopy. The doubly charged cation [{Ru3O(CH3COO)6(py)2}2(BPEB)]2+ was detected in the ESI-MS mass spectrum as a multiple-component isotopomeric ionic cluster centered at m/z 974, which ion abundance and m/z distribution matched perfectly the isotopic pattern calculated for this multiple isotope Ru3-containing ion. The tandem mass spectrum of [{Ru3O(CH3COO)6(py)2}2(BPEB)]2+ provided a structural diagnostic dissociation behavior, on the basis of the characteristic charge splitting and sequential ligand loss steps. The cyclic voltammograms of the complex exhibited a quasi-reversible multistep redox behavior, displaying three waves at 1.14, 0.08, and −1.21 V ascribed to the [Ru3O]2+/1+/0/1− processes and two waves at −1.56 and −1.78 V ascribed to the BPEB0/1−/2− redox processes which are also observed in the free ligand, at −1.48 and 1.61 V, respectively. In spite of the conducting nature of the bridging ligand, the electrochemical and spectroelectrochemical results indicated a weak electronic coupling between the triangular cluster centers. 相似文献
Reactions of [Pt2(μ-S)2(PPh3)4] with the diarylthallium(III) bromides Ar2TlBr [Ar = Ph and p-ClC6H4] in methanol gave good yields of the thallium(III) adducts [Pt2(μ-S)2(PPh3)4TlAr2]+, isolated as their salts. The corresponding selenide complex [Pt2(μ-Se)2(PPh3)4TlPh2]BPh4 was similarly synthesised from [Pt2(μ-Se)2(PPh3)4], Ph2TlBr and NaBPh4. The reaction of [Pt2(μ-S)2(PPh3)4] with PhTlBr2 gave [Pt2(μ-S)2(PPh3)4TlBrPh]+, while reaction with TlBr3 gave the dibromothallium(III) adduct [Pt2(μ-S)2(PPh3)4TlBr2]+[TlBr4]−. The latter complex is a rare example of a thallium(III) dihalide complex stabilised solely by sulfur donor ligands. X-ray crystal structure determinations on the complexes [Pt2(μ-S)2(PPh3)4TlPh2]BPh4, [Pt2(μ-S)2(PPh3)4TlBrPh]BPh4 and [Pt2(μ-S)2(PPh3)4TlBr2][TlBr4] reveal a greater interaction between the thallium(III) centre and the two sulfide ligands on stepwise replacement of Ph by Br, as indicated by shorter Tl-S and Pt?Tl distances, and an increasing S-Tl-S bond angle. Investigations of the ESI MS fragmentation behaviour of the thallium(III) complexes are reported. 相似文献
One neutral [Cu2(enbzpy)(dca)4]n (1) and one polycationic [Ni(enbzpy)(dca)]n(ClO4)n (2) [enbzpy = N,N′-(bis-(pyridin-2-yl)benzylidene)ethane-1,2-diamine; dca = dicyanamide] 1D coordination polymers are synthesized and characterized. X-ray structural analyses reveal each copper(II) center in 1 to adopt a distorted square pyramidal geometry with a CuN5 chromophore coordinated through two N atoms of the Schiff base behaving as a binucleting bis(bidentate) ligand and three nitrile N atoms of one terminal and two single μ1,5 dca units leading to a 1D ladder structure. In 2, each nickel(II) center has a distorted octahedral coordination environment with an NiN6 chromophore bound by four N atoms of enbzpy through tetradentate chelation and two nitrile N atoms of two different single bridged μ1,5 dca units; the latter connects other neighboring metal centers in a non-ending fashion affording a 1D chain. Variable-temperature magnetic susceptibility measurements of 1 and 2 show weak antiferromagnetic interactions among the metal centers through μ1,5 dca bridges. 相似文献
Two new dicyanamide (dicyanamide=[N(CN)2]−, dca) bridged complexes, [Cu(μ1,5-dca)2(phen)]n (1) and [Cd(μ1,5-dca)2(py)2]n (2) have been synthesized and their structures have been determined by X-ray crystallography diffraction. Complex 1 crystallizes in the monoclinic space group P2(1)/c with a=10.1502(3), b=10.9815(4), c=14.5839(4) Å and Z=4. The adjacent copper atoms are connected by single end-to-end dca bridges to form a chain structure along the b axis. The chains are linked via Cu?N weak interactions to give rise to a 2D layer structure, which furthermore into a 3D structure by the π-π interaction between aromatic rings of adjacent layers. Complex 2 crystallizes in the monoclinic space group C2/m with a=6.6849(10), b=17.476(2), c=13.231(2) Å and Z=4. The cadmium(II) center is six-coordinated with a distorted octahedral geometry, bounded to four N atoms of four dca ligands and two N atoms of two-chelated py ligands. Neighbor Cd(II) atoms are linked by the double end-to-end dca bridges to generate a chain structure, which result in a 2D layer structure through the π-π interactions between the adjacent chains with distances 3.641 Å. EPR and magnetic results of 1 suggest that the complex exhibits a weak ferromagnetic interaction through CuNCNCNCu pathways. 相似文献
The heme iron of the β chains of mammalian hemoglobins are rapidly and selectively oxidized in the presence of excess Cu(II) ions in a reaction that requires the presence of a free -SH groups on the β globin chain. The presence of freely reactive -SH groups on the α chains of cat and sheep hemoglobins does not alter the course of this reaction: only the β hemes are oxidized rapidly by Cu(II) in these hemoglobins. Two equivalents of copper are required for the rapid oxidation of the two β chain hemes per mole of cat hemoglobin, in contrast with the four equivalents that are required for reaction with human hemoglobin. The human-cat hybrid hemoglobins, α2Humanβ2Cat and α2Catβ2Human, required two and four equivalents of copper/mol, respectively, for the reaction. Thus, the kinetics and stoichimetry of the reaction are determined by the nature of the β subunit. Analysis of the esr spectra of the products of the reaction of Cu(II) with these hemoglobins indicate that human hemoglobin and the hybrid α2Catβ2Human contain tight binding sites for two equivalents of Cu(II) that are not involved in the oxidation reaction and are not present in cat hemoglobin or α2Humanβ2Cat. Cat β globin like others (sheep, bovine) that lack the tight binding site, has no histidine residue at 2β. It has phenylalanine in this position. These results support the suggestion of Rifkind et al. (Biochemistry 15,5337[1976]) that the tight binding site is near the amino terminal region of the β chain and is associated with histidine 2β. 相似文献
A new rare variety asymmetric μ2-1,1-azido bridged copper(II) complex has been synthesized and characterized structurally and magnetically. The complex [Cu2L2(μ2-1,1-N3)2] · H2O · CH3OH (L = 1-(N-ortho-hydroxyacetophenimine)-2-aminoethane) (1), crystallizes in monoclinic space group, P21/n, with a = 9.469(4) Å, b = 12.526(8) Å, c = 12.899(10) Å, β = 105.79(6)°, V = 1472.2(16) Å3. X-ray study reveals that he Cu-N(azide)-Cu angles in this complex is 90.4°. This is unusually low in comparison to that of the same angle in other end-on azido-bridged binuclear complexes. Though a strong ferromagnetic interaction between the metal centers is expected in the complex, the coupling has actually been found to be antiferromagnetic (J = −4.2 cm−1), instead. To rationalize this paradoxical magnetic behavior, DFT calculation of this and other four complexes with very similar structure have been performed within broken symmetry framework. The calculated magnetic coupling constants (J) are in excellent agreement, both in sign and in the magnitude of the exchange interaction, with the experimental data, and the spin density map is correctly reproduced. 相似文献
The [Co2(CO)6(RC2R′)] complexes (R, R′ = H, Me, Et, Prn) react with molecular hydrogen under mild conditions of temperature and pressure, at low but appreciable rates. The effect of the steric hindrance of the substituents and the strength of the metalcarbon bonds are discussed. The kinetic data measured for [Co2(CO)6(HC2H)], suggest that both H2-coordination and CO-dissociation are involved in the rate-determining step of the overall hydrogenation process.The catalytic activity of [Co2(CO)6(HC2H)] in the homogeneous hydrogenation of acetylene is described. At low substrate/catalyst ratio the initial hydrogenation rate is equal, within experimental error, to that found for the stoichiometric reaction; on increasing the acetylene concentration, cyclotrimerization to benzene becomes the dominant process. Interestingly C4 hydrocarbons (mainly butadiene and 1-butene) are produced in measurable yield (?8%). The formation of these products is interpreted as the result of the hydrogenation of the elusive [Co2(CO)5(HC2H)2] complex, an unstable intermediate in the cyclotrimerization chain. 相似文献
A method for the synthesis of titanocene (IV) aryl carboxylate complexes is presented in this paper. It is based on the fact that alcohol can catalyze the reaction between Cp2TiCl2 and aryl carboxylate ligands in the presence of sodium hydroxide (NaOH). The effects of the catalyst on the reaction system were studied and the possible reaction mechanism was proposed. This method was used to prepare a series of titanocene (IV) aryl carboxylate complexes and a macrocyclic titanocene (5,5′-dithiodisalicylato titanocene), whose structure was determined by X-ray diffraction analysis. 相似文献
Time dependence studies, using high performance liquid chromatography (HPLC), on the reaction between cis-diamminediaquoplatinum and guanine, N1-methylguanine, N7-methylguanine, N9-methylguanine, and N1 ,N7-dimethylguanine are reported. Each reaction gave rise to eight or more compounds; the major components have been prepared and characterization by 1H and 195Pt nuclear magnetic resonance has been attempted. Species of the form ((NH3)2Pt(NO3)-(G-H)-(NO3)-Pt(NH3)2)+, (NH3)2,Pt(G-H)(NO3) monomer and (NH3)2Pt(G-H)(NO3) dimer, where G-H indicates the guanine monoanion, are postulated. 相似文献
Addition of trifluoroacetic acid to syn-[MoO(μ-N-o-tol)(S2CNEt2)]2 in chloroform affords tetranuclear [{Mo2O(S2CNEt2)(η1-O2CCF3)(μ-N-o-tol)2}2(μ-O)(μ-O2CCF3)2] which has been crystallographically characterised. It consists of four molybdenum(V) centres linked via bridging imido, trifluoroacetate and oxo ligands and results from replacement of a dithiocarbamate by two trifluoroacetate ligands. 相似文献
