Basic Carboxylate Research Articles

Structure diversity of a series of new coordination polymers based on a C3-symmetric tridentate ligand with rosette architecture

4,4′,4″-[1,3,5-Benzenetriyltris(carbonylimino)]trisbenzoic acid (H3L), a C3-symmetric ligand, was found to self-assemble into an interesting core-rosette structure driven by intermolecular hydrogen-bonding interactions. Reactions of this ligand with Zn2+, Co2+ and Cd2+ under solvothermal conditions resulted in the formation of four new coordination polymers with interesting structural motifs: [Zn2(L)(OH)(H2O)(DMF)]·DMF·H2O (1), [Co3(L)2(DMF)(H2O)]·DMF·3CH3OH (2), [Co1.5(L)(H2O)(DMF)]·DMF (3), and [Cd1.5(L)(H2O)(DMF)]·DMF (4). Single-crystal structural analysis revealed that complex 1 exhibits a rare example of twofold interpenetrating two-dimensional CdI2-type structure with tetranuclear Zn4(μ3-OH)2(COO)6(H2O)(DMF) serving as secondary building unit (SBU), whereas in 2, the μ3-oxo-tricobalt basic carboxylate SBUs are connected by L3− ligands, leading to a twofold interpenetrating three-dimensional (3,6)-net framework. The isomorphous complexes 3 and 4 each has a (4,4)-grid layered architecture in which the SBU is a linear Co3/Cd3 cluster. The four coordination polymers were all further characterized by IR, thermogravimetric and powder X-ray diffraction (PXRD).

Mechanism for Activation of Triosephosphate Isomerase by Phosphite Dianion: The Role of a Ligand-Driven Conformational Change

The L232A mutation in triosephosphate isomerase (TIM) from Trypanosoma brucei brucei results in a small 6-fold decrease in k(cat)/K(m) for the reversible enzyme-catalyzed isomerization of glyceraldehyde 3-phosphate to give dihydroxyacetone phosphate. In contrast, this mutation leads to a 17-fold increase in the second-order rate constant for the TIM-catalyzed proton transfer reaction of the truncated substrate piece [1-(13)C]glycolaldehyde ([1-(13)C]-GA) in D(2)O, a 25-fold increase in the third-order rate constant for the reaction of the substrate pieces GA and phosphite dianion (HPO(3)(2-)), and a 16-fold decrease in K(d) for binding of HPO(3)(2-) to the free enzyme. Most significantly, the mutation also results in an 11-fold decrease in the extent of activation of the enzyme toward turnover of GA by bound HPO(3)(2-). The data provide striking evidence that the L232A mutation leads to a ca. 1.7 kcal/mol stabilization of a catalytically active loop-closed form of TIM (E(c)) relative to an inactive open form (E(o)). We propose that this is due to the relief, in L232A mutant TIM, of unfavorable steric interactions between the bulky hydrophobic side chain of Leu-232 and the basic carboxylate side chain of Glu-167, the catalytic base, which destabilize E(c) relative to E(o).

Effect of pore structures on selective gas sorption behavior of ultramicroporous MOFs

Synthesis, crystal structures and selective gas sorption properties of two new MOFs based on pyrimidyl-5-carboxylate (pmc) are reported. [Co 3Cl 4(pmc) 2(CH 3OH) 4] ( 1) possesses pillared layer-type network and narrow one-dimensional channels. In [Fe 3(O)(pmc) 5.3(O 2CH) 0.7]·DMF ( 2), the trinuclear basic carboxylate units form a uninodal 5-connected network with isolated cage-like pores. 1 Shows the selective sorption of hydrogen against nitrogen at 77 K and CO 2 against CH 4 at 195 K. For 2, a selective sorption is observed only at 77 K, and the sorption is almost indiscriminate at 195 K. This difference is believed to originate from the different pore structures of 1 and 2.

Dependence of the Chemical Properties of Macrocyclic [NiII2L(μ-O2CR)]+ Complexes on the Basicity of the Carboxylato Coligands (L2− = macrocyclic N6S2 ligand)

The dependence of the properties of mixed ligand [Ni(II)(2)L(μ-O(2)CR)](+) complexes (where L(2-) represents a 24-membered macrocyclic hexaamine-dithiophenolato ligand) on the basicity of the carboxylato coligands has been examined. For this purpose 19 different [Ni(II)(2)L(μ-O(2)CR)](+) complexes (2-20) incorporating carboxylates with pK(b) values in the range 9 to 14 have been prepared by the reaction of [Ni(II)(2)L(μ-Cl)](+) (1) and the respective sodium or triethylammonium carboxylates. The resulting carboxylato complexes, isolated as ClO(4)(-) or BPh(4)(-) salts, have been fully characterized by elemental analyses, IR, UV/vis spectroscopy, and X-ray crystallography. The possibility of accessing the [Ni(II)(2)L(μ-O(2)CR)](+) complexes by carboxylate exchange reactions has also been examined. The main findings are as follows: (i) Substitution reactions between 1 and NaO(2)CR are not affected by the basicity or the steric hindrance of the carboxylate. (ii) Complexes 2-20 form an isostructural series of bisoctahedral [Ni(II)(2)L(μ-O(2)CR)](+) compounds with a N(3)Ni(μ-SR)(2)(μ-O(2)CR)NiN(3) core. (iii) They are readily identified by their ν(as)(CO) and ν(s)(CO) stretching vibration bands in the ranges 1684-1576 cm(-1) and 1428-1348 cm(-1), respectively. (iv) The spin-allowed (3)A(2g) → (3)T(2g) (ν(1)) transition of the NiOS(2)N(3) chromophore is steadily red-shifted by about 7.5 nm per pK(b) unit with increasing pK(b) of the carboxylate ion. (v) The less basic the carboxylate ion, the more stable the complex. The stability difference across the series, estimated from the difference of the individual ligand field stabilization energies (LFSE), amounts to about 4.2 kJ/mol [Δ(LFSE)(2,18)]. (vi) The "second-sphere stabilization" of the nickel complexes is not reflected in the electronic absorption spectra, as these forces are aligned perpendicularly to the Ni-O bonds. (vii) Coordination of a basic carboxylate donor to the [Ni(II)(2)L](2+) fragment weakens its Ni-N and Ni-S bonds. This bond weakening is reflected in small but significant bond length changes. (viii) The [Ni(II)(2)L(μ-O(2)CR)](+) complexes are relatively inert to carboxylate exchange reactions, except for the formato complex [Ni(II)(2)L(μ-O(2)CH)](+) (8), which reacts with both more and less basic carboxylato ligands.

A series of lanthanide–organic polymers incorporating nitrogen-heterocyclic and aliphatic carboxylate mixed-ligands: structures, luminescent and magnetic properties

Seven new lanthanide-organic coordination polymers incorporating both nitrogen heterocyclic dicarboxylate and various auxiliary ligands, {[Ln(3)(Hpimda)(4)(mu(2)-HCOO).5H(2)O].H(2)O}(n)} Ln = Sm (1), Ln = Eu (2), Ln = Gd (3), Ln = Dy (4), Ln = Ho (5), {[Ce(2)(Hpimda)(2)(mu(4)-C(2)O(4)).8H(2)O].2H(2)O}(n) (6), {[Yb(2)(pyda)(mu(4)-C(2)O(4))(2).4H(2)O].3H(2)O}(n) (7) (H(3)pimda = 1H-2-propyl-4,5-imidazoledicarboxylic acid, H(2)pyda = 2,6-pyridinedicarboxylic acid) have been fabricated successfully and characterized systematically. Complexes 1-5 are isomorphous and isostructural, and are built from two-dimensional (2-D) double-decker networks based on the tetranuclear basic carboxylate as a secondary building unit (SBU). Both polymers 6 and 7 feature a (3,4)-connected 3-D framework consisting of 2-D lanthanide-organic hexagonal grids, which are further interlinked via the mu(4)-oxalate ligand. The results of magnetic determination show the same end-to-end bridging fashion of formate group results in different magnetic properties occurring between lanthanide centers. The luminescence emission spectra of the complexes vary depending on the lanthanide ion present.

Rational design of covalently bridged [FeIII2MIIO] clusters

We are reporting the first supramolecular dimeric units of basic carboxylates. The neutral [Fe(III)₂M(II)O] motif for different 3d M metals is covalently bound through 2,2'-bipyrimidine. We have structurally characterized the hexanuclear clusters and the related trinuclear building blocks. Their magnetic properties have been fully analyzed and DFT calculations have been performed as a supplementary tool. All results evidence a weak antiferromagnetic interaction through the bpym bridge between isolated spin ground states (in some examples) arising from intra-Fe₂MO core exchange couplings.

DFT broken-symmetry exchange couplings calculation in a 1D chain of bridged iron basic carboxylates

DFT broken-symmetry calculations at the B3LYP level were carried out to evaluate the exchange coupling constants defined by the Heisenberg–Dirac–van Vleck spin Hamiltonian (HDvV), Ĥ = −2 JŜ aŜ b, in a 1D chain of iron basic carboxylate cores [Fe 3O(Piv) 6(H 2O)] bridged by dicyanamide, and two related trinuclear Fe 3O moieties. The chain complex was modeled as two Fe 3O units that preserve all features of the repetitive unit in the infinite real system. All geometries were taken from the crystallographic data previously reported. The obtained calculated values for the J constants are in good agreement with experimental results. The weak anti-ferromagnetic inter-Fe 3O core interaction along the chain is also reasonably accounted by the calculations. This methodology appears as a useful tool in the theoretical evaluation of exchange coupling constants in 1D systems.

Structural and Magnetic Characterization of a μ-1,5-Dicyanamide-Bridged Iron Basic Carboxylate [Fe3O(O2C(CH3)3)6] 1D Chain

We are reporting an unprecedented example of a mu-1,5-dicyanamide (dca)-bridged iron basic carboxylate, [Fe3O(O2C(CH3)3)6], 1D chain. As revealed from X-ray determination, the Fe3O cores are arranged in a zigzag configuration along the chain and strictly aligned in the same plane. The chains are well-isolated by the bulky tert-butyl groups. Magnetic measurements showed that the Fe3O units are weakly antiferromagnetically coupled (J = -0.6 cm(-1)) through the dca ligand while possessing a well-isolated S = 1/2 spin ground state arising from competing antiferromagnetic interactions.

Facile Concerted Proton−Electron Transfers in a Ruthenium Terpyridine-4′-Carboxylate Complex with a Long Distance Between the Redox and Basic Sites

We have designed and prepared ruthenium complexes with terpyridine-4'-carboxylate (tpyCOO) ligands, in which there are six bonds between the redox-active Ru and the basic carboxylate. The protonated Ru(II) complex, RuII(dipic)(tpyCOOH) (Ru(II)COOH), is prepared in one-pot from [(p-cymene)RuCl2]2, tpyCOONa, and then sodium pyridine-2,6-dicarboxylate [Na(dipic)]. A crystal structure of the deprotonated Ru(II) complex, Ru(II)COO-, shows a distance of 6.9 A between the metal and basic sites. The Ru(III) complex (Ru(III)COO) has been isolated by one-electron oxidation of Ru(II)COO- with triarylaminium radical cations (NAr3*+). Ru(III)COO has a bond dissociation free energy (BDFE) of 81 +/- 1 kcal mol(-1), from pKa and E1/2 measurements. It oxidizes 2,4,6-tri-tert-butylphenol (BDFE = 77 +/- 1 kcal mol(-1)) by removal of e- and H+ (triple bond H*) to form 2,4,6-tri-tert-butylphenoxyl radical and Ru(II)COOH, with a second-order rate constant of (2.3 0.2) x 10(4) M(-1) s(-1) and a kH/kD of 7.7 1.2. Thermochemical analysis suggests a concerted proton-electron transfer (CPET) mechanism for this reaction, despite the 6.9 A distance between the redox-active Ru and the H+-accepting oxygen. Ru(III)COO also oxidizes the hydroxylamine TEMPOH to the stable free radical TEMPO and xanthene to bixanthyl. These reactions appear to be similar to processes that have been previously termed hydrogen atom transfer.

Metal−Organic Framework Based on a Trinickel Secondary Building Unit Exhibiting Gas-Sorption Hysteresis

An interpenetrating microporous metal-organic framework based on a mu3-oxotrinickel basic carboxylate secondary building unit has been synthesized and structurally characterized. It exhibits pronounced gas-sorption hysteresis and selective adsorption of carbon dioxide over methane.

Initial use of di-2-pyridyl ketone oxime in chromium carboxylate chemistry: Triangular [formula omitted] compounds and unexpected formation of a carboxylate-free dichromium(II,II) complex

A systematic investigation of the [Cr 3O(O 2CCMe 3) 6(H 2O) 3](O 2CCMe 3)/(py) 2CNOH [(py) 2CNOH = di-2-pyridyl ketone oxime] reaction system is described, involving the determination of the influence of the Cr III:(py) 2CNOH ratio, the temperature and the presence of counterions on the identity of the reaction products. As a consequence, complexes [Cr 2{(py) 2CNO} 4] · 2H 2O ( 1 · 2H 2O), [Cr 3OCl(O 2CCMe 3) 4{(py) 2CNO} 2] · 2Me 2CO ( 2 · 2Me 2CO) and [Cr 3O(O 2CCMe 3) 4{(py) 2CNO} 2(H 2O)](NO 3) · H 2O · 0.5Me 2CO ( 3 · H 2O · 0.5Me 2CO) have been isolated and structurally characterized by single-crystal X-ray studies. (py) 2CNO − behaves as a N, N′-bidentate chelating and/or N, N′, O-tridentate bridging ligand binding through one 2-pyridyl and the oximate nitrogen atoms, and/or the oximate oxygen atom. 1 is a relatively stable air-stable dinuclear Cr(II) complex with no metal–metal bonding arising, from the ligand-assisted reduction of the ‘basic carboxylate’ Cr(III) triangle. The structures of 2 and 3 consist of similar neutral and cationic triangles of Cr III ions, respectively, centered by a triply bridging oxo ligand and with two edge-bridging oximate groups from the two 2.1110 (py) 2CNO − ligands. Variable-temperature magnetic susceptibility studies and EPR data for 2 reveal an antiferromagnetically-coupled system with an S T = 3/2 ground state. Solid-state IR and ligand field spectra of 2 are briefly discussed in terms of its structure.

Lightest member of the basic carboxylate structural pattern: [Al(3)(mu)-O)(mu(2)CCF(3))(6)(THF)(3)][(Me(3)Si)(3)CAl(O(2)CCF(3))(3)] x C(7)H(8).

[Al3(μ3-O)(μ-O2CCF3)6(THF)3][(Me3Si)3CAl(OC(O)CF3)3]·C7H8 is the first characterized μ3-oxo-trinuclear basic carboxylate of aluminum closing the gap of isomorphism with the transition metal analogues. The system is an excellent case study for the electronic structure, approached by DFT-B3LYP calculations. The actual system proves that the oxo-trinuclear pattern is stabilized by the chemical hardness of oxygen donors and by highly symmetric intramolecular packing of the ligands.

Mixed-terminal-ligand oxo-centered carboxylate-bridged trinuclear complexes: gas phase generation by means of electrospray ionization FT-ICR MS, condensed phase synthesis, and X-ray structure of K +[Cr 3O(C 6H 5COO) 6(F) 2(H 2O)] −·2(CH 3) 2CO

The current state of knowledge concerning mixed-terminal-ligand oxo-centered carboxylate-bridged trinuclear complexes is summarized and the application of mass spectrometric techniques to the study of trinuclear basic carboxylates is briefly reviewed. The exchange/substitution reactions of terminal ligands with other molecules in both liquid and gas phase have been investigated using electrospray ionization Fourier transform-ion cyclotron resonance mass spectrometry (ESI FT-ICR MS), studying the clusters [Fe 3O(pivalato) 6(H 2O) 3] +ClO 4 − ( 1), [Cr 3O(RCOO) 6(L) 3] +ClO 4 − (R=C(CH 3) 3, L=H 2O ( 2); R=C 6H 5, L=H 2O ( 3), CH 3OH ( 4), or piperidine ( 5)) as well as [(C 2H 5) 2NH 2] + 2[Fe 3O((CH 3) 2CHCH 2COO) 6(F) 3] 2−·CH 3CN·2CHCl 3 ( 6) and K +[Cr 3O(C 6H 5COO) 6(F) 2(H 2O)] −·2(CH 3) 2CO ( 7). It was established that factors influencing the quantitative and qualitative yields of products in the ion–molecule collisions/reactions occurring in the ESI source are: skimmer voltage, capillary voltage, ion accumulation time in the hexapole, capillary temperature, pressure in the hexapole region, and the properties of the atomic or molecular system used for concomitant creation of background pressure and providing reagent for ion–molecule reactions. Under ‘soft’ ESI conditions coordinatively saturated gaseous ions [(core)(L) 3] + (where [core] +=[Cr 3O(RCOO) 6] +) could be generated and supramolecular self-assembled entities [(Anion)(core) 2(L) 6] + (where Anion −=ClO 4 − for coordination compounds 2– 5 or F − for 7) and [(ClO 4){(core)(H 2O)(L) 2} 3] 2+ (for compound 3 in methanol) pre-existing in solution were detected. The ESI FT-ICR MS study revealed that the [(core)(L) 3] + ions lose L molecules as a result of undergoing dissociation by the absorption of blackbody infrared radiation. Based on studies of exchange/substitution reactions in the liquid phase, two new methods of condensed phase synthesis of mixed-terminal-ligand species are proposed: (a) an ‘aged solutions’ strategy; and (b) site-directed gradual replacement of terminal ligands via supramolecular assemblies. Also, a new compound, K +[Cr 3O(C 6H 5COO) 6(F) 2(H 2O)] −·2(CH 3) 2CO, was synthesized and X-ray crystallographic analysis (at 120 K) was employed to confirm its ‘unsymmetric’ structure.

The hydrolysis of a Co(III) chelated amide catalyzed by an internal phosphonic acid group

In a previous study it was found that an internal carboxylate ion contributed nothing to the rate of hydrolysis of a Co(III) complex of a glycine anilide, although in the enzyme carboxy-peptidase A the catalyzed hydrolysis of peptides is performed by a carboxylate and a Zn 2+ ion. However, external acetate ion and even more so external phosphate ion were effective cocatalysts. In the current work we have incorporated a phosphonate ion as an internal cocatalyst for the hydrolysis of a Co(III) complex of a glycine anilide, in two different versions. The internal phosphonate group indeed proves to be effective. The contrast with an ineffective carboxylate ion may in part reflect a different stereoelectronic requirement, but a principal contributor is the increased basicity of the phosphonate group. Its p K a is still not as high as that of the abnormal carboxylate in the enzyme. It is suggested that phosphate or phosphonate groups may be better models than carboxylate ions for the abnormally basic carboxylates found in some enzymes.

New trinuclear, oxo-centered, basic carboxylate compounds of transition metals. 3. Syntheses and x-ray studies of the trivanadium(III,III,III) and trivanadium(II,III,III) compounds [V3(.mu.3-O)(CH3CO2)6(CH3COOH)2(THF)]+[VCl4(CH3COOH)2]- and V3(.mu.3-O)(CF3CO2)6(THF)3 with "classical" triangular structures

New trinuclear, oxo-centered, basic carboxylate compounds of transition metals. 3. Syntheses and x-ray studies of the trivanadium(III,III,III) and trivanadium(II,III,III) compounds [V3(.mu.3-O)(CH3CO2)6(CH3COOH)2(THF)]+[VCl4(CH3COOH)2]- and V3(.mu.3-O)(CF3CO2)6(THF)3 with "classical" triangular structures

New trinuclear, oxo-centered, basic carboxylate compounds of transition metals. 2. Synthesis and x-ray structure of V3(O)3(THF)(C6H5CO2)6, a compound with a deviant structure

New trinuclear, oxo-centered, basic carboxylate compounds of transition metals. 2. Synthesis and x-ray structure of V3(O)3(THF)(C6H5CO2)6, a compound with a deviant structure

New trinuclear, oxo-centered, basic carboxylate compounds of transition metals. 1. Trichromium(II,III,III) compounds

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew trinuclear, oxo-centered, basic carboxylate compounds of transition metals. 1. Trichromium(II,III,III) compoundsF. Albert Cotton and Wenning WangCite this: Inorg. Chem. 1982, 21, 7, 2675–2678Publication Date (Print):July 1, 1982Publication History Published online1 May 2002Published inissue 1 July 1982https://doi.org/10.1021/ic00137a028RIGHTS & PERMISSIONSArticle Views381Altmetric-Citations44LEARN 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 (506 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Exchange interactions in a series of novel heteronuclear basic carboxylate complexes containing two iron(III) ions and a divalent metal ion

Complexes [Fe2IIIMIIO(MeCO2)6py3]py (M = Mg, Mn, Co, Ni, or Zn; py = pyridine), isomorphous(except for M = Ni) with the mixed-valence compounds [M3O(MeCO2)6py3]py (M = Mn or Fe), are reported; their magnetic properties provide new information about superexchange pathways in the trinuclear basic carboxylate system.

Basic Chromium(III) Carboxylates: Reactions of Chromium(III) Chloride with Some Carboxylic Acids

Abstract Anhydrous chromium(III) chloride reacts with pure carboxylic acids (RCOOH where R = CH3, C2H5, n-C3H7, CH2Cl, CHCl2 and CCl3) to give basic trinuclear chromium(III) carboxylates of the general formula [Cr3O(OOCR)6]+Cl-. The reaction of CrCl3 with acetic anhydride, however, gives a partially substituted product, CrCl(OOCCH3)2.The formation of basic carboxylates has been attributed to the strong affinity of Cr3+ ions for water that they can abstract it even from pure carboxylic acids. Their addition compounds with ammonia have also been prepared. The compounds have been characterized by their elemental analyses, IR, molar conductance and magnetic measurements.

Properties of molten carboxylates part 6. A quantiative differential thermal analysis study of phase transitions in some zinc and cadmium carboxylates

Quantitative DTA results are presented for the phase changes in some cadmium and zinc n-alkanoates. Cadmium carboxylates form liquid crystal phases. The total entropy of the solid-to-liquid transition is small indicating a high degree of aggregation in the isotropic liquid. The phases previously reported by Skoulios are shown to be due to the presence of basic carboxylates. The zinc carboxylates have solid—solid transformations but do not form liquid crystal phases. The entropies of fusion are of the same order as those in the lead salts showing only a small degree of aggregation in the liquid.