The Stereochemistry of Some Cobalt(III) Complexes with Ethylenediamine-N,N'-diacetic Acid and Some N-Substituted Analogs

Legg, J. Ivan; Cooke, Dean W.

doi:10.1021/ic50033a010

Cited by 102 publications

(20 citation statements)

References 1 publication

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“…Soc., 82, 1474 (1960). 4) tetrakis(d/-mandelato(zirconium (isomer A), (5) hydroxytris(lactato(zirconium, (6) product of Z-mandelato and zirconium.…”

Section: Discussionmentioning

confidence: 99%

“…The nature of the ligand conformations in such coordination number six species was first examined by Corey and Bailar4 567and refined by others. [5][6][7] Considerable thought8•9 has gone into the nature of the coordination polyhedra suitable for species of higher coordination number and the dimensional restraints of the ligand bite, but little attention Has been given to the stereospecific effects of ligands. It is of interest, therefore, to look for stereospecific effects of optically active ligands in potential coordination number eight complexes.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Zirconium(IV) and hafnium(IV) complexes of .alpha.-hydroxy carboxylates, lactates, mandelates, and isopropylmandelates. Stereospecificity in eight-coordinate complexes

Larsen¹,

Homeier²

1972

Inorg. Chem.

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The infrared spectra of deuterated (d¡) and protonated tetrakis (di-mandelato(zirconium(IV) and -hafnium(IV) are indicative of a structure containing considerable hydrogen bonding. The neutral stoichiometric tetrakis product from aqueous solution is obtained only with the racemic ligand, suggesting that dl ligand pairs provide a stereospecificity suitable for the formation of stabilizing hydrogen bonds which ligands of one handedness do not provide. A polymeric structure possessing bridging ligand pairs between metal ions is proposed. In acetonitrile, mandelic acid reacts with zirconium tetrachloride by anion replacement, to yield a mixture of monochlorotris(mandelato (zirconium and tetrakis(S-mandelato )zirconium(I V) with an infrared spectrum different from that of the aqueous polymeric product.(1) Abstracted in part from the thesis of E. H. Homeier submitted to the Graduate School in partial fulfillment of the requirements for the Ph.D. degree. Presented in part before the Division of Inorganic Chemistry at the 157th National Meeting of the American Chemical Society, Minneapolis,

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“…Soc., 82, 1474 (1960). 4) tetrakis(d/-mandelato(zirconium (isomer A), (5) hydroxytris(lactato(zirconium, (6) product of Z-mandelato and zirconium.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Zirconium(IV) and hafnium(IV) complexes of .alpha.-hydroxy carboxylates, lactates, mandelates, and isopropylmandelates. Stereospecificity in eight-coordinate complexes

Larsen¹,

Homeier²

1972

Inorg. Chem.

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“…C, H, N Elemental analyses were performed by Atlantic Microlab Inc. (Norcross, GA); Fe elemental analyses were performed on a Varian Spectra 55B atomic absorption spectrometer. Though the di-hydrochloride salt of 2,2′-(2-((carboxymethyl)(methyl)amino)ethylazanediyl)-diacetic acid (N 2 O 3 ) 43 and the barium salt of 2,2′-(ethane-1,2-diylbis(methylazanediyl))diacetic acid (N 2 O 2 ) 44 have been prepared previously, the unified procedures carried out in this work can be found in the ESI. †…”

Section: Experimental General Proceduresmentioning

confidence: 99%

Studies of iron(ii) and iron(iii) complexes with fac-N2O, cis-N2O2 and N2O3 donor ligands: models for the 2-His 1-carboxylate motif of non-heme iron monooxygenases

et al. 2012

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Enzymes in the oxygen-activating class of mononuclear non-heme iron oxygenases (MNOs) contain a highly conserved iron center facially ligated by two histidine nitrogen atoms and one carboxylate oxygen atom that leave one face of the metal center (three binding sites) open for coordination to cofactor, substrate, and/or dioxygen. A comparative family of [Fe(II/III)(N(2)O(n))(L)(4-n))](±x), n = 1-3, L = solvent or Cl(-), model complexes, based on a ligand series that supports a facially ligated N,N,O core that is then modified to contain either one or two additional carboxylate chelate arms, has been structurally and spectroscopically characterized. EPR studies demonstrate that the high-spin d(5) Fe(III)g = 4.3 signal becomes more symmetrical as the number of carboxylate ligands decreases across the series Fe(N(2)O(3)), Fe(N(2)O(2)), and Fe(N(2)O(1)), reflecting an increase in the E/D strain of these complexes as the number of exchangeable/solvent coordination sites increases, paralleling the enhanced distribution of electronic structures that contribute to the spectral line shape. The observed systematic variations in the Fe(II)-Fe(III) oxidation-reduction potentials illustrate the fundamental influence of differential carboxylate ligation. The trend towards lower reduction potential for the iron center across the [Fe(III)(N(2)O(1))Cl(3)](-), [Fe(III)(N(2)O(2))Cl(2)](-) and [Fe(III)(N(2)O(3))Cl](-) series is consistent with replacement of the chloride anions with the more strongly donating anionic O-donor carboxylate ligands that are expected to stabilize the oxidized ferric state. This electrochemical trend parallels the observed dioxygen sensitivity of the three ferrous complexes (Fe(II)(N(2)O(1)) < Fe(II)(N(2)O(2)) < Fe(II)(N(2)O(3))), which form μ-oxo bridged ferric species upon exposure to air or oxygen atom donor (OAD) molecules. The observed oxygen sensitivity is particularly interesting and discussed in the context of α-ketoglutarate-dependent MNO enzyme mechanisms.

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“…Assignments were made utilizing 2D (COSY, XH CORR) experiments for selected complexes. Although low-field (60 MHz) 1 H NMR data are given in the literature for [Co(EDDA)(en)] + , , the high-field 1 H and 13 C NMR data reported here allow more complete assignments of chemical shifts and coupling constants. NMR data have not previously been given for L = Men and BEE.…”

Section: Discussionmentioning

confidence: 93%

Condensation Reactions of Cobalt Amino Acid Complexes with Formaldehyde: Preparation and Crystal Structures of Cobalt Complexes Containing New Hexadentate, Pendant-Arm Macrocyclic and Acyclic Ligands

et al. 1997

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The reaction of cobalt(III) complexes α-cis-[Co(EDDA)L]+ containing both amino acid (EDDA, ethylenediamine-N,N‘-diacetate) and bidentate amine ligands (L = en, ethylenediamine; Men, N-methylethylenediamine; BEE, N,N‘-diethylethylenediamine; DEE, N,N-diethylethylenediamine) with formaldehyde under basic conditions has been investigated. For L = en, the product is [Co(L1)]+, which contains a macrocyclic ligand (L1 = 1,4-bis(carboxymethyl)-6,13-dioxacyclam) formed by linking the primary nitrogens on the en ligand with the secondary nitrogens on the EDDA ligand through two CH2OCH2 bridges. For L = Men and DEE, which each contain only one primary nitrogen, the reaction gives complexes [Co(L2)]+ and [Co(L3)]+ bearing hexadentate acyclic ligands (L2 = 1,4-bis(carboxymethyl)-11-ethyl-6-oxa-1,4,8,11-tetraazatridecane; L3 = 1,4-bis(carboxymethyl)-6-oxa-1,4,8,11-tetraazadodecane) each resulting from formation of one new CH2OCH2 linkage. All complexes have been characterized by 1H and 13C NMR, IR, and UV−visible spectroscopy and cyclic voltammetry. The X-ray crystal structures of [Co(L1)]Cl·3H2O and [Co(L3)]PF6·NH4PF6·H2O have been determined. [Co(L1)]Cl·3H2O is monoclinic, P21/n, with a = 14.792(3) Å, b = 7.766(1) Å, c = 16.520(4) Å, β = 99.54(2)°, V = 1871.5(6) Å3, Z = 4, R = 0.042. [Co(L3)]PF6·NH4PF6·H2O is monoclinic, P21/n, with a = 13.353(6) Å, b = 11.595(2) Å, c = 16.900(5) Å, β = 95.59(3)°, V = 2604(2) Å3, Z = 4, R = 0.107.

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The Stereochemistry of Some Cobalt(III) Complexes with Ethylenediamine-N,N'-diacetic Acid and Some N-Substituted Analogs

Cited by 102 publications

References 1 publication

Zirconium(IV) and hafnium(IV) complexes of .alpha.-hydroxy carboxylates, lactates, mandelates, and isopropylmandelates. Stereospecificity in eight-coordinate complexes

Zirconium(IV) and hafnium(IV) complexes of .alpha.-hydroxy carboxylates, lactates, mandelates, and isopropylmandelates. Stereospecificity in eight-coordinate complexes

Studies of iron(ii) and iron(iii) complexes with fac-N2O, cis-N2O2 and N2O3 donor ligands: models for the 2-His 1-carboxylate motif of non-heme iron monooxygenases

Condensation Reactions of Cobalt Amino Acid Complexes with Formaldehyde: Preparation and Crystal Structures of Cobalt Complexes Containing New Hexadentate, Pendant-Arm Macrocyclic and Acyclic Ligands

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