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Binuclear Complexes (binuclear + complex)
Selected AbstractsX-ray Diffraction and Solid-State NMR Studies of a Germanium Binuclear ComplexCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2006Luís Mafra Abstract A compound formulated as (C4H12N2)[Ge2(pmida)2(OH)2],4,H2O (where pmida4,=N -(phosphonomethyl)iminodiacetate and C4H12N22+=piperazinedium cation), containing the anionic [Ge2(pmida)2(OH)2]2, complex, has been synthesised by the hydrothermal approach and its structure determined by single-crystal X-ray diffraction analysis. Several high-resolution solid-state magic-angle spinning (MAS) NMR techniques, in particular two-dimensional 1H,X(13C,31P) heteronuclear correlation (HETCOR) and 1H,1H homonuclear correlation (HOMCOR) experiments incorporating a frequency-switched Lee,Goldburg (FS-LG) decoupling scheme, have been employed for the first time in such a material. Using these tools in tandem affords an excellent general approach to study the structure of other inorganic,organic hybrids. We assigned the NMR resonances with the help of C,,,H and P,,,H internuclear distances obtained through systematic statistical analyses of the crystallographic data. The compound was further characterised by powder X-ray diffraction techniques, IR and Raman spectroscopy, and by elemental and thermal analyses (thermogravimetric analysis and differential scanning calorimetry). [source] Asymmetric meso -Epoxide Ring-Opening with Trimethylsilyl Cyanide Promoted by Chiral Binuclear Complexes of Titanium.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Dichotomy of CC versus CN Bond Formation Abstract In the presence of chiral catalysts derived from the same chiral hexadentate ligand and aluminium, zinc or titanium ions, the reaction between cyclohexene oxide and trimethylsilyl cyanide can be controlled to give predominantly either the nitrile (up to 99% ee) or the isonitrile product (up to 94% ee). The metal ion, ligand stereochemistry and base concentration all play a role in determining the product ratio. [source] Cyano-bridged Ln3+ -Cr3+ Binuclear Complexes [Ln(L)x(H2O)yCr(CN)6]·mL·nH2O (Ln=La,Nd, x=5, y=2, m=1 or 2, n=2 or 2.5; Ln=Sm,Dy, Er, x=4, y=3, m=0, n=1.5 or 2.0; L=2-pyrrolidinone): Structure, Magnetism and Spin Density MapCHINESE JOURNAL OF CHEMISTRY, Issue 3 2007Xian-Ru Sun Abstract In order to shed light upon the nature and mechanism of 4f-3d magnetic exchange interactions, a series of binuclear complexes of lanthanide(3+) and chromium(3+) with the general formula [Ln(L)5(H2O)2Cr(CN)6]·mL·nH2O (Ln=La (1), Ce (2), Pr (3), Nd (4); x=5, y=2, m=1 or 2, n=2 or 2.5; L=2-pyrrolidinone) and [Ln(L)4(H2O)3Cr(CN)6] ·nH2O (Ln=Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Er (10); x=4, y=3, m=0, n=1.5 or 2.0; L2-pyrrolidinone) were prepared and the X-ray crystal structures of complexes 2, 6 and 7 were determined. All the compounds consist of a Ln-CN-Cr unit, in which Ln3+ in a square antiprism environment is bridged to an octahedral coordinated Cr3+ ion through a cyano group. The magnetic properties of the complexes 3 and 6,10 show an overall antiferromagnetic behavior. The fitting to the experimental magnetic susceptibilities of 7 give g=1.98, J=0.40 cm,1, zJ,=,0.21 cm,1 on the basis of a binuclear spin system (SGd=7/2, SCr=3/2), revealing an intra-molecular Gd3+ -Cr3+ ferromagnetic interaction and an inter-molecular antiferromagnetic interaction. For 7 the calculation of quantum chemical density functional theory (DFT), combined with the broken symmetry approach, showed that the calculated spin coupling constant was 20.3 cm,1, supporting the observation of weak ferromagnetic intra-molecular interaction in 7. The spin density distributions of 7 in both the high spin ground state and the broken symmetry state were obtained, and the spin coupling mechanism between Gd3+ and Cr3+ was discussed. [source] The new three-dimensional supramolecule bis{,-2-[(4-hydroxybenzoyl)hydrazonomethyl]phenolato}bis[aquacopper(II)] dinitrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2008Hua Yin In the title centrosymmetric binuclear complex, [Cu2(C14H11N2O3)2(H2O)2](NO3)2, the two metal centres are bridged by the phenolate O atoms of the ligand, forming a Cu2O2 quadrangle. Each Cu atom has a distorted square-pyramidal geometry, with the basal donor atoms coming from the O,N,O,-tridentate ligand and a symmetry-related phenolate O atom. The more weakly bound apical donor O atom is supplied by a coordinated water molecule. When a further weak Cu...O interaction with the 4-hydroxy O atom of a neighbouring cation is considered, the extended coordination sphere of the Cu atom can be described as distorted octahedral. This interaction leads to two-dimensional layers, which extend parallel to the (100) direction. The two-dimensional polymeric structure contrasts with other reported structures involving salicylaldehyde benzoylhydrazone ligands, which are usually discrete mono- or dinuclear Cu complexes. The nitrate anions are involved in a three-dimensional hydrogen-bonding network, featuring intermolecular N,H...O and O,H...O hydrogen bonds. [source] Synthesis, characterization and biological activity of diphenyltin(IV) complexes of N -(3,5-dibromosalicylidene)-,-amino acid and their diphenyltin dichloride adductsAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 1 2006Laijin Tian Abstract Diphenyltin(IV) complexes of N -(3,5-dibromosalicylidene)-,-amino acid, Ph2Sn[3,5-Br2 -2-OC6H2 CHNCH(R)COO] (where R = H, Me, i -Pr, Bz), and their 1:1 adducts with diphenyltin dichloride, Ph2Sn[3,5-Br2 -2-OC6H2CHNCH(R)COO]·Ph2SnCl2, have been synthesized and characterized by elemental analysis, IR and NMR (1H, 13C and 119Sn) spectra. The crystal structure of Ph2Sn[3,5-Br2 -2-OC6H2CHNCH(i -Pr)COO] shows a distorted trigonal bipyramidal geometry with the axial locations occupied by a carboxylate,oxygen and a phenolic,oxygen atom of the ligand, and that of Ph2Sn[3,5-Br2 -2-OC6H2CHNCH(i -Pr)COO]·Ph2SnCl2 reveals that the two tin atoms are joined via the carbonyl atom of the ligand to form a mixed organotin binuclear complex. Bioassay indicates that the compounds possess better cytotoxic activity against three human tumor cell lines (HeLa, CoLo205 and MCF-7) than cis -platin and moderate antibacterial activity against two bacteria (E. coli and S. aureus). Copyright © 2005 John Wiley & Sons, Ltd. [source] A New Hydroxo-bridged Chromium(III) Dimer [Cr(saltn)OH]2·4H2O: Synthesis, Crystal Structure and Magnetic PropertiesCHINESE JOURNAL OF CHEMISTRY, Issue 6 2005Ni Zhong-Hai Abstract A new hydroxo-bridged dimeric Cr(III) complex [Cr(saltn)OH]2·4H2O [H2saltn=N,N,-bis(salicylidene)trimethylenediamine] has been synthesized and its structural and magnetic properties have been investigated. The complex crystallizes in the triclinic space group P -1 with one dimeric formula unit in a cell of dimensions a=0.95828(19) nm, b=0.95926(19) nm, c=1.0437(2) nm, ,=86.77(3)°, ,=82.48(3)°, and ,=64.93(3)°. The geometry around each chromium(III) center is six-coordinate, distorted-octahedral. The bridging Cr2O2 unit is strictly planar, as required by the crystallographic symmetry. The CrOCr, bridging angle is 99.94(16)°, and the distance between Cr,Cr, is 0.3019 nm. The magnetic susceptibility of the complex has been examined in the range of 2-300 K. By using the spin-spin coupled model for an S1=S2=3/2 dimeric system , the magnetic data were fitted to give the parameters of g=2.01(1), J=-0.85(2) cm -1, and zJ' =0.18(3)cm -1, indicating the presence of a weak antiferromagnetic spin-exchange interaction between the Cr(III) ions in the binuclear complex. [source] Mono-, Bi-, Tri- and Tetranuclear Palladium(II), Copper(I), and Gold(I) Complexes of Morpholine- and N -Methylpiperazine-Functionalized Cyclodiphosph(III)azans, cis -[(tBuN-,)2(PNC4H8X)2] (X = O, NMe)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 26 2010Maravanji S. Balakrishna Abstract Bis(amido)cyclodiphosphazanes, cis -[(tBuN-,)2(PNC4H8O)2] (2) and cis -[(tBuN-,)2(PNC4H8NMe)2] (3) were synthesized by treating the corresponding amines with cis -[ClP(tBuN-,)2PCl] (1). The stoichiometric reactions of 2 or 3 with elemental sulfur and selenium afforded the bis-chalcogenides, cis -[(tBuN-,)2(P(E)NC4H8X)2] (X = O, E = S; 4, X = NMe, E = S; 5, X = O, E = Se; 6, X = O, E = Se; 7). The reactions of 2 or 3 with [PdCl2(SMe2)2] produced exclusively the mononuclear trans -[PdCl2{(tBuN-,)2(PNC4H8X)2}2] (X = O; 8, X = NMe; 9), whereas the reactions with [Pd(,-Cl)(,3 -C3H5)]2 afforded the bimetallic complexes [{PdCl(,3 -C3H5)}2{(tBuN-,)2(PNC4H8X)2}] (X = O; 10, X = NMe; 11) in good yield. Treatment of 2 or 3 with [AuCl(SMe2)] in 1:1 and 1:2 molar ratios yielded the mono- and binuclear complexes, [{AuCl(tBuN-,)2(PNC4H8O)2}] (X = O; 12, X = NMe; 13), [{AuCl}2{(tBuN-,)2(PNC4H8O)2}] (X = O; 14, X = NMe; 15), respectively. The PdII (8) and AuI (12) complexes were used as metallo-ligands to prepare homo- and heterometallic complexes, trans -[PdCl2{(tBuN-,)2(PNC4H8O)2}2{Pd(,3 -C3H5)Cl}2] (16), trans -[PdCl2{(tBuN-,)2(PNC4H8O)2}2(AuCl)2] (17), and [Cu(CH3CN)(,-Cl)2Cu(CH3CN){(tBuN-,)2(PNC4H8O)2}2(AuI)2](18). The crystal structures of 2, 4, 7,9, 14, 15, and 18 were established by single-crystal X-ray diffraction studies. [source] Effects of Zinc(II) on the Luminescence of Europium(III) in Complexes Containing , -Diketone and Schiff BasesHELVETICA CHIMICA ACTA, Issue 11 2009Yuko Hasegawa Abstract The UV, excitation, and luminescence spectra of tris(pivaloyltrifluoroacetonato)europium(III) ([Eu(pta)3]; Hpta=1,1,1-trifluoro-5,5-dimethylhexane-2,4-dione=HA) were measured in the presence of bis(salicylidene)trimethylenediamine (H2saltn), bis[5-(tert- butyl)salicylidene]trimethylenediamine (H2(tBu)saltn), or bis(salicylidene)cyclohexane-1,2-diyldiamine (H2salchn), and the corresponding ZnII complexes [ZnB] (B=Schiff base). The excitation and luminescence spectra of the solution containing [Eu(pta)3] and [Zn(salchn)] exhibited much stronger intensities than those of solutions containing the other [ZnB] complexes. The introduction of a tBu group into the Schiff base was not effective in sensitizing the luminescence of [Eu(pta)3]. The luminescence spectrum of [ZnB] showed a band around 450,nm. The intensity decreased in the presence of [Eu(pta)3], reflecting complexation between [Eu(pta)3] and [ZnB]. On the basis of the change in intensity against the concentration of [ZnB], stability constants were determined for [Eu(pta)3Zn(saltn)], [Eu(pta)3Zn{(tBu)saltn}], and [Eu(pta)3Zn(salchn)] as 4.13, 4.9 and 5.56, respectively (log,, where =[[Eu(pta)3ZnB]]([[Eu(pta)3]][[ZnB]]),1). The quantum yields of these binuclear complexes were determined as 0.15, 0.11, and 0.035, although [Eu(pta)3Zn(salchn)] revealed the strongest luminescence at 613,nm. The results of X-ray diffraction analysis for [Eu(pta)3Zn(saltn)] showed that ZnII had a coordination number of five and was bridged with EuIII by three donor O-atoms, i.e., two from the salicylidene moieties and one from the ketonato group pta. [source] Synthesis of rhodium(III) complexes with tris/tetrakis-benzimidazoles and benzothiazoles,quick identification of cyclometallation by nuclear magnetic resonance spectroscopyMAGNETIC RESONANCE IN CHEMISTRY, Issue 8 2009N. Chandrashekhar Abstract Reactions of rhodium(III) halides with multidentate N,S -heterocycles, (LH3) 1,3,5-tris(benzimidazolyl)benzene (L1H3; 1), 1,3,5-tris(N -methylbenzimidazolyl) benzene (L2H3; 2) and 1,3,5-tris(benzothiazolyl)benzene (L3H3; 3), in the molar ratio 1:1 in methanol,chloroform produced mononuclear cyclometallated products of the composition [RhX2(LH2)(H2O)] (X = Cl, Br, I; LH2 = L1H2, L2H2, L3H2). When the metal to ligand (1,3 or 1,2,4,5-tetrakis(benzothiazolyl)benzene [L4H2; 4]) molar ratio was 2:1, the reactions yielded binuclear complexes of the compositions [Rh2Cl5(LH2)(H2O)3] (LH2 = L1H2, L2H2, L3H2) and [Rh2X4(L4)(H2O)2] (X = Cl, Br, I). Elemental analysis, IR and 1H nuclear magnetic resonance (NMR) chemical shifts supported the binuclear nature of the complexes. Cyclometallation was detected by conventional 13C NMR spectra that showed a doublet around ,190 ppm. Cyclometallation was also detected by gradient-enhanced heteronuclear multiple bond correlation (g-HMBC) experiment that showed cross-peaks between the cyclometallated carbon and the central benzene ring protons of 1,3. Cyclometallation was substantiated by two-dimensional 1H1H correlated experiments (gradiant-correlation spectroscopy and rotating frame Overhauser effect spectroscopy) and 1H13C single bond correlated two-dimensional NMR experiments (gradient-enhanced heteronuclear single quantum coherence). The 1H15N g-HMBC experiment suggested the coordination of the heterocycles to the metal ion via tertiary nitrogen. Copyright © 2009 John Wiley & Sons, Ltd. [source] Binuclear Terbium(III) Complex as a Probe for Tyrosine PhosphorylationCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2010Hiroki Akiba Abstract By using the luminescence from binuclear complexes of TbIII (Tb2 -L1 and Tb2 -L2), phosphorylated Tyr residue in peptides was selectively detected in neutral aqueous solutions. Neither the non-phosphorylated Tyr, pSer, pThr, nor the other phosphate-containing biomolecules tested affected the luminescence intensity to any notable extent. Upon the binding of the pTyr to these TbIII complexes, the luminescence from the metal ion was notably promoted, as the light energy absorbed by the benzene ring of pTyr is efficiently transferred to the TbIII center. The binding activity of the binuclear TbIII complexes towards pTyr is two orders of magnitude larger than that of the corresponding mononuclear complex. These binuclear complexes were successfully used for real-time monitoring of enzymatic phosphorylation of a peptide by a tyrosine kinase. [source] The Diversity of Difluoroacetylene Coordination Modes Obtained by Coupling Fluorocarbyne Ligands on Binuclear Manganese Carbonyl SitesCHEMISTRY - A EUROPEAN JOURNAL, Issue 22 2009Xian-mei Liu Abstract One Mn or two? The fluorocarbyne manganese carbonyl complexes [Mn(CF)(CO)n] (n=3,,4) and [Mn2(CF)2(CO)n] (n=4,7; see picture) have been investigated by density functional theory. In mononuclear complexes the CF ligand behaves very much like the NO ligand in terms of ,-acceptor strength. In binuclear complexes the two CF ligands couple in many of the low-energy structures to form a bridging C2F2 ligand derived from difluoroacetylene. Recent work has shown that the fluorocarbyne ligand CF, isoelectronic with the NO ligand, can be generated by the defluorination of CF3 metal complexes, as illustrated by the 2006 synthesis by Hughes et,al. of [C5H5Mo(CF)(CO)2] in good yield by the defluorination of [C5H5Mo(CF3)(CO)3]. The fluorocarbyne ligand has now been investigated as a ligand in the manganese carbonyl complexes [Mn(CF)(CO)n] (n=3,,4) and [Mn2(CF)2(CO)n] (n=4,7) by using density functional theory. In mononuclear complexes, such as [Mn(CF)(CO)4], the CF ligand behaves very much like the NO ligand in terms of ,-acceptor strength. However, in the binuclear complexes the two CF ligands couple in many of the low-energy structures to form a bridging C2F2 ligand derived, at least formally, from difluoroacetylene, FCCF. The geometries of such [Mn2(C2F2)(CO)n] complexes suggest several different bonding modes of the bridging C2F2 unit. These include bonding through the orthogonal ,,bonds of FCCF, similar to the well-known [R2C2Co2(CO)6] complexes, or bonding of the C2F2 unit as a symmetrical or unsymmetrical biscarbene. This research suggests that fluorocarbyne metal chemistry can serve as a means for obtaining a variety of difluoroacetylene metal complexes, thereby avoiding the need for synthesizing and handling the very unstable difluoroacetylene. [source] Cyano-bridged Ln3+ -Cr3+ Binuclear Complexes [Ln(L)x(H2O)yCr(CN)6]·mL·nH2O (Ln=La,Nd, x=5, y=2, m=1 or 2, n=2 or 2.5; Ln=Sm,Dy, Er, x=4, y=3, m=0, n=1.5 or 2.0; L=2-pyrrolidinone): Structure, Magnetism and Spin Density MapCHINESE JOURNAL OF CHEMISTRY, Issue 3 2007Xian-Ru Sun Abstract In order to shed light upon the nature and mechanism of 4f-3d magnetic exchange interactions, a series of binuclear complexes of lanthanide(3+) and chromium(3+) with the general formula [Ln(L)5(H2O)2Cr(CN)6]·mL·nH2O (Ln=La (1), Ce (2), Pr (3), Nd (4); x=5, y=2, m=1 or 2, n=2 or 2.5; L=2-pyrrolidinone) and [Ln(L)4(H2O)3Cr(CN)6] ·nH2O (Ln=Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Er (10); x=4, y=3, m=0, n=1.5 or 2.0; L2-pyrrolidinone) were prepared and the X-ray crystal structures of complexes 2, 6 and 7 were determined. All the compounds consist of a Ln-CN-Cr unit, in which Ln3+ in a square antiprism environment is bridged to an octahedral coordinated Cr3+ ion through a cyano group. The magnetic properties of the complexes 3 and 6,10 show an overall antiferromagnetic behavior. The fitting to the experimental magnetic susceptibilities of 7 give g=1.98, J=0.40 cm,1, zJ,=,0.21 cm,1 on the basis of a binuclear spin system (SGd=7/2, SCr=3/2), revealing an intra-molecular Gd3+ -Cr3+ ferromagnetic interaction and an inter-molecular antiferromagnetic interaction. For 7 the calculation of quantum chemical density functional theory (DFT), combined with the broken symmetry approach, showed that the calculated spin coupling constant was 20.3 cm,1, supporting the observation of weak ferromagnetic intra-molecular interaction in 7. The spin density distributions of 7 in both the high spin ground state and the broken symmetry state were obtained, and the spin coupling mechanism between Gd3+ and Cr3+ was discussed. [source] | ||||||||||