Carboxylato Ligands Research Articles

Syntheses and characterization of anti-inflammatory dinuclear and mononuclear zinc indomethacin complexes. Crystal structures of [Zn2(indomethacin)4(L)2] (L = N,N-dimethylacetamide, pyridine, 1-methyl-2-pyrrolidinone) and [Zn(indomethacin)2(L1)2] (L1 = ethanol, methanol).

The syntheses and spectral and structural characterizations of Zn(II) indomethacin [1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indole-3-acetic acid = IndoH] complexes, as different solvent adducts, have been studied. The complexes are unusual in that both monomeric and dimeric complexes are formed and that this is the first example of the same carboxylato ligand binding via both carboxylate oxygen atoms in monomeric and dimeric Zn(II) complexes. The crystal structures of Zn-Indo complexes with N,N-dimethylacetamide (DMA), pyridine (Py), 1-methyl-2-pyrrolidinone (NMP), EtOH, and MeOH as solvent ligands, [Zn2(Indo)4(DMA)2].2DMA, 1, [Zn2(Indo)4(Py)2].2H2O, 2b, [Zn2(Indo)4(NMP)2], 3, cis-[Zn(Indo)2(EtOH)2], 4, and cis-[Zn(Indo)2(MeOH)2], 5, were determined. Complexes 1, 2b, and 3 crystallize in the triclinic space group P1 (No. 2): a = 13.628(2) A, b = 17.462(2) A, c = 11.078(1) A, alpha = 99.49(1) degrees, beta = 108.13(1) degrees, gamma = 110.10(1) degrees for 1; a = 13.347(3) A, b = 16.499(5) A, c = 10.857(1) A, alpha = 99.48(2) degrees, beta = 108.25(2) degrees, gamma = 106.24(2) degrees for 2; a = 14.143(3) A, b = 14.521(2) A, c = 11.558(2) A, alpha = 109.07(1) degrees, beta = 90.80(2) degrees, gamma = 116.40(1) degrees for 3. The three complexes exhibit dinuclear paddle-wheel structures with a Zn...Zn distance of 2.9686(6) A, Zn-ORCOO distances of 2.035(2)-2.060(2) A, and a Zn-ODMA distance of 1.989(2) A in 1, a Zn...Zn distance of 2.969(1) A, Zn-ORCOO distances of 2.020(3)-2.049(3) A, and a Zn-NPy distance of 2.036(3) A in 2, and a Zn...Zn distance of 2.934(1) A, Zn-ORCOO distances of 2.009(3)-2.051(3) A, and a Zn-ONMP distance of 1.986(3) A in 3. In these cases, the zinc ions are offset along the z direction such that the L-Zn...Zn-L moiety is nonlinear, unlike the Cu analogues. Each Zn has a square-pyramidal geometry bridged by four carboxylato ligands in the basal plane with the solvent ligands containing an O- or N-donor atom at the apex. Complexes 4 and 5 are isostructural, with space group C2/c (No. 15). For 4, a = 30.080(2) A, b = 5.3638(6) A, c = 24.739(2) A, beta = 90.342(7) degrees, and for 5, a = 29.419(2) A, b = 5.320(2) A, c = 24.461(2) A, beta = 90.840(4) degrees. The Zn resides on a 2-fold axis and the complexes have a distorted cis octahedral structure with Zn-ORCOO bond lengths of 2.183(3) and 2.169(3) A, a Zn-OEtOH bond length of 2.015(3) A in 4, Zn-ORCOO bond lengths of 2.195(2) and 2.151(2) A, and a Zn-OMeOH bond length of 2.022(3) A in 5.

Studies of the synthesis and thermochemistry of coordinatively unsaturated chelate complexes (eta 5-C5Me5)IrL2 (L2 = TsNCH2CH2NTs, TsNCH2CO2, CO2CO2).

A comparative synthetic, structural, and thermochemical study on a series of chelate complexes containing the fragment (eta 5-C5Me5)Ir [(eta 5-C5Me5)Ir(TsNCH2CH2NTs) (1), (eta 5-C5Me5)Ir(TsNCH2CO2) (2), (eta 5-C5Me5)Ir(CO2CO2) (3)] was performed to clarify the roles of carboxylato and sulfonamido ligands. Whereas 1 and 2 are monomeric in solution and in the solid state, 3 appears to exist as an oligomer or polymer, (3)n, which can be broken up by addition of a ligand L such as a phosphine, CO, or 2-methoxypyridine to form (eta 5-C5Me5)Ir(L)(CO2CO2) (6). The synthesis of (3)n from [(eta 5-C5Me5)IrCl(mu-Cl)]2 required the use of silver oxalate in CH3CN, but if other solvents were used, the bridging oxalato complex (eta 5-C5Me5)IrCl(mu-eta 2-eta 2-C2O4)ClIr(eta 5-C5Me5) (7) was obtained and identified by X-ray diffraction. Enthalpies for reaction of THF-soluble monomers 1 and 2 with PMe3 were determined to be -28.7(0.5) and -28.5(0.4) kcal mol-1, respectively. The oligomerization behavior of 3 may be a result of reduced sigma- or pi-donation of carboxylato ligands compared to N-tosylamido ligands, because the values for nu CO in oxalato and bissulfonamido complexes 6-CO and (eta 5-C5Me5)Ir(CO)(TsNCH2CH2NTs) (4-CO) were 2064 and 2042 cm-1, respectively.

Synthesis and characterization of platinum(II) complexes with 3-methylpiperidine: crystal and molecular structure of [Pt(3-methylpiperidine) 2(malonato)]·H 2O

A series of new platinum complexes of the type [Pt(3-mepip) 2X] (where 3-mepip=3-methylpiperidine, and X=dichloro, sulfato, oxalato, malonato, methylmalonato, dimethylmalonato, tartronato, 1,1-cyclopropanedicarboxylato (CPDCA) or 1,1-cyclobutanedicarboxylato (CBDCA) ligand) were synthesized and characterized by elemental analysis, IR spectroscopy and 195Pt nuclear magnetic resonance spectroscopy. The crystal structure of [Pt(3-mepip) 2(malonato)]·0.79H 2O was determined by single crystal X-ray diffraction. In this complex platinum has slightly distorted square planar geometry with two adjacent corners being occupied by two nitrogens of 3-methylpiperidine, whereas the remaining two adjacent corners are occupied by two oxygen atoms of the malonato group. An intricate network of intermolecular hydrogen bonds holds the crystal lattice together. In the other complexes, 3-mepip acts as non-leaving ligands, whereas the carboxylato ligands act as leaving groups.

Structure and properties of di-μ-acetato-dichlorobis(2,2′-bipyridine)dirhodium(II)-trihydrate

Reduction of [Rh2(μ-OAc)2(bpy)2(H2O)2](OAc)2 and [Rh2Cl2(μ-OAc)2(bpy)2] · 3H2O complexes with ethanol and [Cr2(OAc)4(H2O)2] has been investigated using e.p.r. and u.v.–vis. spectra. The results indicate that stable complexes containing the [Rh23+] entity are not formed. The X-ray structure of [Rh2Cl2(μ-OAc)2(bpy)2] · 3H2O has been determined. Coordination around the Rh atom is in the form of a distorted octahedron. The complex shows an almost ideal eclipsed conformation. The equatorial coordination sites are occupied by bridging carboxylato ligands and 2,2′-bipyridine and axial positions by the Cl ligand and the rhodium atom. The Rh–Rh distance is 2.574 A.

Modifying the properties of platinum(IV) complexes in order to increase biological effectiveness

The preparation of a series of novel Pt(IV) complexes containing the anionic polyfluoroaryl ligands, 2,3,5,6-tetrafluorophenyl ( p-HC 6F 4), 2,3,5,6-tetrafluoro-4-methoxyphenyl ( p-MeOC 6F 4) and pentafluorophenyl (C 6F 5) are described. The crystal structure of a representative complex, [Pt( p-MeOC 6F 4) 2(O 2CEt) 2(en)] (en=ethane-1,2-diamine) was determined and confirms the trans arrangement of the carboxylato ligands. Reduction potentials of the series of complexes reveal that replacement of equatorial chloro ligands by polyfluoroaryl ligands makes reduction substantially more difficult. They also confirm previously reported trends in that complexes having axial carboxylato ligands are more readily reduced than those having axial hydroxo ligands. Reduction potentials and in vitro activities showed no obvious correlations. Moderate to high activity was observed for many complexes in the series, including some of those that were very difficult to reduce.

Investigation of the Unusual Electronic Structure of Pyrococcus furiosus 4Fe Ferredoxin by EPR Spectroscopy of Protein Reduced at Ambient and Cryogenic Temperatures.

The hyperthermophilic archaeon Pyrococcus furiosus contains a novel ferredoxin (Pf-Fd) in which, in the native 4Fe form, three of the Fe ions are coordinated to the protein by cysteinyl thiolato ligands, but the fourth Fe is coordinated by an aspartyl carboxylato ligand ([Fe(4)S(4)(cys)(3)(asp)](2)(-)(,3)(-)). Chemical reduction at ambient temperature of the oxidized 4Fe form (Pf-Fd 4Fe-ox, S = 0 ground state, with the cluster core indicated by [Fe(4)S(4)](2+)(ox)) produces a reduced 4Fe form (Pf-Fd 4Fe-red, with the cluster core indicated by [Fe(4)S(4)](+)(red)). Pf-Fd 4Fe-red, [Fe(4)S(4)](+)(red) core, in frozen solution exhibits S = (1)/(2) and (3)/(2) electronic states that are not in thermal equilibrium. The two spin states thus represent alternate ground states of the reduced cluster (cluster cores indicated by [Fe(4)S(4)](+)(red1) and [Fe(4)S(4)](+)(red2), respectively), rather than a ground and excited spin state. Low-temperature (77 K) reduction of 4Fe-ox in frozen solution by gamma-irradiation produces in high yield the reduced state of the cluster that is trapped in the structure of the oxidized parent cluster, and thus has a cluster core denoted by [Fe(4)S(4)](+)(ox). The [Fe(4)S(4)](+)(ox) form also exhibits non thermally converting S = (3)/(2) and (1)/(2) components in the same proportion as seen for [Fe(4)S(4)](+)(red). The EPR signal of the S = (3)/(2) component that results from cryoreduction ([Fe(4)S(4)](+)(ox2)) is indistinguishable, within experimental variability, from that seen in the ambient-temperature, chemically reduced protein ([Fe(4)S(4)](+)(red2)), and the signals of the two S = (1)/(2) components ([Fe(4)S(4)](+)(ox1) and [Fe(4)S(4)](+)(red1), respectively) closely resemble each other, although they are not identical. Previous NMR studies at ambient temperature showed evidence for only one species in fluid solution for both Pf-Fd 4Fe-ox and 4Fe-red. Taken together, the NMR and EPR results indicate that fluid solutions of either oxidized or reduced Pf-Fd contain only one conformer, but that frozen solutions of each contain two distinct conformers, with each one of the pair of oxidized protein forms having a corresponding reduced form. A shift in the coordination mode of the aspartyl carboxylato ligand is proposed to account for this conformational flexibility.

Preparation and Structure of Ru2(µ−O2CCF3)2(CO)4(NCMe)2

The molecular structure of Ru2(µ-O2CCF3)2(CO)4(NCMe)2, obtained from Ru3(CO)10(NCMe)2 and CF3CO2H, or from Ru3(CO)12 and CF3CO2H in a CH2Cl2/MeCN mixture, is presented. The central Ru–Ru bond [2·683(1) Å] is bridged by the two carboxylato ligands [Ru–O (average) 2·133 Å]. Each ruthenium carries mutually cis CO ligands approximately trans to the Ru–O vectors and an MeCN ligand in the axial position [Ru–N (average) 2·18 Å].

Crystal structure of [Mn(II)(phen)(ClCH2COO)2]n (phen = 1,10−phenanthroline)

A new polymeric manganese(II) complex, [Mn(II)(phen)(ClCH2COO)2]n, was obtained from the reaction of Mn(ClCH2COO)2 with phen and its structure was determined by x-ray crystallography. The complex crystallizes in the monoclinic system, space group C2/c with a = 19.706(4), b = 11.381(3), c = 7.482(3) A, β = 94.01(3)°, V = 1674.0(8) A3, and Z = 4. The structure consists of an infinite chain. The manganese atom is located on a twofold axis and presents a distorted octahedral coordination sphere, which consists of the two N atoms of a phen ligand (Mn—N = 2.304(2) A) and four carboxylato ligands. The Mn···Mn distance within the chain is 4.53 A, and the carboxylato bridges present a syn-anti conformation.

Synthesis, crystal structure and magnetic properties of a polymeric copper(II) Schiff-base complex having binuclear units covalently linked by isonicotinate ligands †

The polynuclear copper(II) complex [{Cu2L(O2CC5H4N)}. C2H5OH](x) (1), where H3L is a 1r2 Schiff base derived from 1,3-diaminopropan-2-ol and salicylaldehyde, has been prepared and structurally characterized. The structure consists of a one-dimensional zigzag chain in which the binuclear [Cu2L](+) units are covalently linked by isonicotinate ligands to give a syndiotactic arrangement of the copper ions protruding outside the chain. In the basic unit, the copper(II) centres are bridged by an alkoxo and a carboxylato ligand, giving a Cu ... Cu distance of 3.492(3) Angstrom and a Cu-O-Cu angle of 130.9(2)degrees. While one copper centre has a square-planar geometry, the other copper is square-pyramidal with the pyridine nitrogen being the axial ligand. The visible electronic spectrum of 1 shows a broad d-d band at 615 nm. The complex shows a rhombic X-band EPR spectral pattern in the polycrystalline phase at 77 K. Magnetic susceptibility measurements in the temperature range 22 to 295 K demonstrate the antiferromagnetic behaviour of 1. A theoretical fit to the magnetic data is based on a model assuming 1 as an equimolar mixture of copper atoms belonging to an antiferromagnetically coupled one-dimensional Heisenberg chain with the other copper atoms outside the chain behaving like paramagnetic centres.

Mono- and polynuclear complexes from the reaction of palladium acetate with α-substituted thioethers and thiols

Palladium acetate reacts with α-substituted thioethers (RSCH(R′)Z; Z=ester, ketone, sulphone, substituted methyl) and the thiol HSCH 2C(O)Me to give complexes whose composition and nuclearity depend mainly on the electronic properties of the sulphur ligand. If it contains sufficiently acidic hydrogen atoms, the acetato group is partially or totally removed as acetic acid to give complexes of the type [Pd 3( μ-O 2CMe) 3( μ-RSCR′Z) 3] and [Pd(SCH 2C(O)Me) 2] 6. The stability of the trimers decreases with the steric hindrance of the substituents at the sulphur and at the methine carbon atoms. Stable mixed sphere complexes are obtained also with carboxylato ligands different from acetato as PhCOO − and MeSCH 2COO −. When the substituted thioether has poor electronwithdrawing groups, its reaction with palladium acetate affords complexes of the type [Pd( η 1-OAc) 2(RSCH 2Z) 2], in which the sulphur donor atom has simply replaced one oxygen atom of the acetato ligand.

Reactions of Tetrakis[bis(trimethylsilyl)methyl]digallane(4) with Carboxylic Acids — Substituent Exchange and Bridging of the GaGa bond by two Carboxylato Groups

AbstractYellow tetrakis[bis(trimethylsilyl)methyl]digallane(4) 1 reacts with two equivalents of the carboxylic acids RCOOH (R = −C6H5, −p−BrC6H4, −3,5‐Me2C6H3, −CMe3) to yield almost quantitatively colorless products in which two bis(trimethylsilyl)methyl groups are replaced by two carboxylato ligands. As shown by a crystal structure determination with the 4‐bromo‐phenyl derivative (3), the GaGa bond is bridged by both carboxylato groups in a chelating manner. The GaGa distance is shortened to 238.5(2) pm (1: 254.1(1) pm) and the coordination number of the Ga atoms increased to four.

Comparison with Several Oxidation States of Ruthenium Binuclear Complexes; Ruthenium Analogue for Iron- Protein Active Site Model

Abstract Alkoxo bridged ruthenium dinuclear complexes as a non-heme diiron protein active site model, [Ru(III)2(dhpta)(O2CR)2]− (H5dhpta=1, 3-diamino-2- hydroxypropane-N,N,N′,N′-tetraacetic acid, R=CH3(1), C6H5(2), C6H4-p-OH(3), C6H4-p-NH2(4)) exhibited the strongly antiferromagnetically coupled magnetic behavior (H = −2J*S 1*S2, -J=310∼470 cm−1). The magnetic interaction between Ru(III) ions varies depending on the bridged carboxylato ligand. The one- electron reduced Ru(II)Ru(III) mixed-valence states by electrolysis shows two absorption bands in the near-IR region, which the lowest energy one might be intervalence charge transfer (IT) band. Hush theory was applied to analyze the IT band in the lowest energy, the electronic coupling integral, Had was estimated to be 670–870 cm−1. The interaction between the Ru(II)Ru(III) mixed valence state is weaker than that of the Ru(III)Ru(III) states. With one-electron oxidized complex (2), Ru(III)Ru(IV) mixed-valence state, two absorption bands appeared in the nea...

Synthesis and Some Reactions of Molybdenocene Derivatives Coordinated with the Chiral Carboxylato Ligands

Abstract Molybdenocene derivatives with some chiral carboxylato ligand of the types, Cp2MoH(OCOR*), Cp2Mo(OCOR*)2, Cp2MoH(OCO-E*-OCO)MoHCp2, [Cp2Mo(OCOR*)]+R*CO2−, are prepared by the reaction of Cp2MoH2 with chiral 2-methylbutanoic acid, mandelic acid, O-acetylmandelic acid, tartaric acid, and O,O′-diacetyltartaric acid in the presence of ketone and are characterized spectroscopically. Enantioselectivity in the reduction of the prochiral ketones using some of these hydridocarboxylato derivatives is examined.

Crystal and molecular structure of aqua(2,2′-bipyridine)bis(betaine)copper(II) perchlorate monohydrate

A new monomeric copper(II) complex with 2,2′-bipyridine (bpy) and betaine (bet), [Cu(byy)(bet)2(H2O)](ClO4)2 · H2O, has been prepared and characterized by X-ray crystallography. The complex crystallizes in the triclinic space groupP-1 witha=8.859(2),b=11.191(2),c=14.850(3) A, α=91.41(1), β=97.19(1), γ=91.97(1)°,V=1459.2(7) A3, andZ=2. The structure comprises discrete cations [Cu(bpy)(bet)2(H2O)]2+ in which the metal atom is coordinated in a distorted square-pyramidal environment by two oxygen atoms from a pair of monodentate carboxylato ligands [Cu−O=1.950(2) A] and two nitrogen atoms of a bidentate bpy ligand [Cu−N=1.997(3)−2.005(3) A] on the basal plane, and one aqua [Cu−O=2.267(3) A] ligand at the apical position.

Octadecanuclearity in Manganese Carboxylate Chemistry: K4[Mn18O16(O2CPh)22(phth)2(H2O)4] (phthH2 = phthalic acid)

Small change—large effect: If some of the carboxylato ligands in the coordination sphere of the anion in 1, which contains the butterfly‐like [Mn4(μ3‐O)2] unit, are replaced by dicarboxylato ligands by treatment with potassium hydrogen phthalate, the title compound 2 containing an Mn18O16 framework in its anion is formed. It is the largest Mn/O aggregate discovered to date. equation image

Simultaneous binding of nitrato, o-phenanthroline, and carboxylato ligands to manganese(II). Structure of [Mn(phen)(Me 3NCH 2CO 2)(NO 3)(H 2O) 2](NO 3) · H 2O

The crystal structure of [Mn(phen)(bet)(NO 3)(H 2O) 2](NO 3) · H 2O (phen = o-phenanthroline, bet = Me 3N +CH 2CO 2 −) has been established by X-ray diffraction. The complex features the [Mn(phen)(bet)(NO 3)(H 2O) 2] + cation in which the metal atom is coordinated by a bidentate phen [MnN 2.275(3), 2.302(4) Å], a unidentate carboxylato group of bet [2.194(4) Å], a unidentate nitrato group [2.260(4) Å] and two aqua ligands [2.190(3), 2.195(3) Å] in a highly distorted octahedral environmental

Reactivity of ruthenium carbonyl carboxylates under hydroformylation conditions

Ru(CO) 2(MeCOO) 2(PBU 3) 2, Ru 2(CO) 4(MeCOO) 2(PBu 3) 2, Ru 4(CO) 8(MeCOO) 4(PBu 3) 2, and [Ru 2(CO) 4(MeCOO) 2] n react, in the presence of CO, with molecular hydrogen, losing the carboxylato ligand while the metal is reduced to Ru(O). Evidence is given of the involvement of ruthenium hydrides in this reaction. The role of the above precursors in the catalytic cycle of the hydroformylation of olefins is discussed.

Molecular Recognition within a Rigid Host: Structural Changes Induced in μ‐Carboxylato Dimetal(II) Complexes by Replacing Steric Repulsions with Hydrogen Bonds

Small change-large effect. When two Nmethyl groups on one N atom are replaced by hydrogen atoms in each of the diamino hgands in 1, M = Co, the bridging aqua ligand is ousted and an asymmetric dicobalt complex with one five-coordinate, one six-coordinate metal center, and three bridging carboxylato ligands results. This type of structural tuning is important for modeling, for example, the metal coordination environment in diiron(ii) non-heme proteins in which a coordination site on one metal is open.

Synthesis of Optically Active Ferrocene Analogues of Salicylic Acid Derivatives and Rhodium(II)-Catalyzed Asymmetric Intramolecular C–H Insertion of α-Diazo β-Keto Esters Using New Chiral Carboxylato Ligands

Abstract The ferrocene analogue of salicylic acid, 2-hydroxyferrocenecarboxylic acid was synthesized via monolithiation of ferrocene with t-butyllithium, and resolved to optically active forms. Optically active 2-hydroxyferrocenecarboxylic acid was converted to 1-hydroxyferrocenecarbaldehyde, ferrocene analogue of salicylaldehyde, and 2-alkoxyferrocenecarboxylic acids. The later compounds were used as chiral carboxylato ligands for the rhodium(II)-catalyzed asymmetric intramolecular C–H insertion of α-diazo β-keto esters (up to 42% ee).

Metal-metal cooperation via 1,1'-bis(diphenylphosphino)ferrocene (dppf). 1. Structurally distinctive silver(I) dppf complexes of nitrato and carboxylato ligands in variable coordination modes. Crystal structures of [Ag(NO3)(dppf)]2.cntdot.2CHCl3, [Ag2(HCO2)2(dppf)3].cntdot.2CH2Cl2, [Ag2(CH3CO2)2(dppf)]2, and Ag2(C6H5CO2)2(dppf)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMetal-metal cooperation via 1,1'-bis(diphenylphosphino)ferrocene (dppf). 1. Structurally distinctive silver(I) dppf complexes of nitrato and carboxylato ligands in variable coordination modes. Crystal structures of [Ag(NO3)(dppf)]2.cntdot.2CHCl3, [Ag2(HCO2)2(dppf)3].cntdot.2CH2Cl2, [Ag2(CH3CO2)2(dppf)]2, and Ag2(C6H5CO2)2(dppf)T. S. Andy Hor, Soh Ping Neo, Chee Siong Tan, Thomas C. W. Mak, Kevin W. P. Leung, and Ru Ji WangCite this: Inorg. Chem. 1992, 31, 22, 4510–4516Publication Date (Print):October 1, 1992Publication History Published online1 May 2002Published inissue 1 October 1992https://doi.org/10.1021/ic00048a014RIGHTS & PERMISSIONSArticle Views390Altmetric-Citations74LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (905 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts