The tris[(.+-.)-trans-1,2-cyclohexanediamine]cobalt(III) system

Harnung, Sven E.; Soerensen, B. S.; Creaser, I. I.; Maegaard, H.; Pfenninger, U.; Schaeffer, C. E.

doi:10.1021/ic50163a023

Cited by 58 publications

(34 citation statements)

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“…S20, ESI †). [14][15][16][17] and to the structural results for 1-4 discussed above, the stereochemistry at the metal in 7 is a (4) 3.067 (7) 128 View Article Online surprise: it represents the first solid in which only the Λ configuration is encountered. Fig.…”

Section: Resultsmentioning

confidence: 88%

“…It is a hard and inert cation for which only slow racemization can be expected. The energetic preference for the Δ configuration at the central atom of the octahedral ĳMĲR,R-chxn) 3 ] 3+ complex cations was established for M = Co by Harnung and coworkers 14 and is reflected by the fact that this diastereomer represents the readily available main product from crystallization experiments for ĳMĲR,R-chxn) 3 ]Cl 3 ·nH 2 O (M = Co, Rh), 15 ĳCrĲR,R-chxn) 3 ]Cl 3 ·nH 2 O (ref. We can confirm this earlier report, but our attempts to resolve CrĲacacCN) 3 into enantiomers in an analogous way were not successful: we only achieved low enantiomeric excess and very modest yields.…”

Section: Introductionmentioning

confidence: 99%

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Interplay of ligand chirality and metal configuration in mononuclear complexes and in a coordination polymer of Cr(iii)

2015

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In order to investigate the influence of ligand chirality on the configuration of the coordinated metal, five pseudooctahedral CrĲIII) complexes with one or two chelating R,R-1,2-diaminocyclohexane ligands have been synthesized. The mononuclear complexes ĳCrĲR,R-chxn) 2 ClĲDMSO)]Cl 2 , ĳCrĲR,R-chxn) 2 Cl 2 ]Cl, ĳCrĲacacCN)ĲR,R-chxn) 2 ]ĲNO 3 ) 2 , ĳCrĲacacCN) 2 ĲR,R-chxn)]NO 3 , ĳCrĲacacCN) 2 ĲR,R-chxn)]PF 6 . (R,R-chxn = R,R-1,2-diaminocyclohexane; acacCN = deprotonated 3-cyanoacetylacetone and DMSO = dimethyl sulfoxide) have been obtained as crystalline solids, mostly solvates, and the potential chirality transfer from the enantiopure ligand to the configuration at the CrĲIII) center has been investigated. The cationic complex ĳCrĲacacCN) 2 ĲR,R-chxn)] + has been synthesized as exclusively Λ configured at the metal. In this complex, the dangling nitrile groups of the ditopic acacCN ligands may coordinate to AgĲI): the chiral-at-metal building block has thus been converted to the 2D network AgĳCrĲacacCN) 2 ĲR,R-chxn)] 2 ĲPF 6 ) 3 under retention of the stereochemistry at CrĲIII). With respect to topology, the polycations in this mixed-metal coordination polymer correspond to two interpenetrated {4,4} nets. CrystEngCommThis journal is † Electronic supplementary information (ESI) available: Crystallographic information in CIF format; details concerning crystallization, structure solution and refinement of 1-4 and 6-8; hydrogen bonds in 1, 2, 6 and 8; displacement ellipsoid plots of asymmetric unit for 1-4 and 6-8; powder patterns for 1, 2, 4, 5, 6, 7 and 8. CCDC 1047808-1047814. For ESI and crystallographic data in CIF or other electronic format see

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Section: Resultsmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Interplay of ligand chirality and metal configuration in mononuclear complexes and in a coordination polymer of Cr(iii)

2015

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“…-'A2 transition and a negative sign for the 'A1 -'E transition are indicative of the A configuration for Co(en)P and lel3-Co-(ch~n)3~+ complexes. 11 We extend this correlation of CD signs with configuration to the mixed-ligand complexes as well. Again, we note thesimilarity of the CDspactra of thedifferent complexes, with some changes in the relative intensities of the components noted above.…”

Section: T B ( D P a ) 3 * A N D T B (~D A ) 3~~e N C Ementioning

confidence: 72%

Chiral discrimination in electronic energy transfer between dissymmetric lanthanide(III) and cobalt(III) complexes in solution: effects of ligand size, shape, and configuration in the acceptor complexes

Metcalf¹,

Bolender²,

Driver³

et al. 1993

J. Phys. Chem.

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Chiral discrimination in electronic energy-transfer processes is investigated for a series of systems in which the energy donors and acceptors are dissymmetric metal complexes. The sample systems contain a racemic mixture of luminescent donor complexes in solution with an enantiomerically resolved concentration of nonluminescent acceptor complexes. Chiral discrimination in the donor-acceptor electronic energy-transfer processes produces differential quenching kinetics for the two enantiomeric structures in the donor excited-state population, and these quenching kinetics are characterized by time-resolved chiroptical luminescence (TR-CL) measurements.The rate parameters obtained from these measurements provide a basis for assessing the degree and Sense of chiral recognition between the dissymmetric donor and acceptor complexes in solution. Four different donor complexes and four different acceptor complexes are examined in this study. The donor complexes are Eu(dpa)s3-, Tb(dpa)s3-, Eu(cda)3+, and Tb(cda)3&, where dpa dipicolinate dianion and cda I chelidamate trianion.Among these complexes there are significant differences in electronic state structures (between the Eu3+ and Tb3+ complexes) and in net charge (between the dpa and cda complexes), but the size, shape, and stereochemical properties of these complexes are very similar. In contrast, the acceptor complexes employed in this study have identical net charges and similar electronic state structures, but they differ significantly with respect to size, shape, and stereochemical details. These complexes are optical isomers of C0(en)3~+, Co(en)~(R,R-chxn)~+, Co(en)(R,R-chxn)z3+, and Co(R,R-chxn)s3+, where en ethylenediamine and R,R-chxn E trans-( 1R,2R)-1,2-diaminocyclohexane. The quenching data obtained in this study show largevariations among the 16 different donor-acceptor systems investigated, and these variations include changes in both the degree and sense of enantioselecrive quenching. The observed variations in quenching behavior are correlated with a number of donor and acceptor properties, including charge, size, shape, elements of structural chirality, and the donor and acceptor electronic state structures relevant to resonance energy-transfer processes.

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“…22a In another study, Harnung was able to equilibrate diastereomers of the trichloride salt [Co(trans-chxn) 3 ] 3+ 3Cl À . 29 As shown in Fig. 14, an aqueous solution of the racemate, both enantiomers of which have lel 3 orientations (Fig.…”

Section: Ligand Conformation: (Ss)-and (Rr)-12-diphenylethylenediamentioning

confidence: 99%

Octahedral Werner complexes with substituted ethylenediamine ligands: a stereochemical primer for a historic series of compounds now emerging as a modern family of catalysts

et al. 2016

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As reported by Alfred Werner in 1911-1912, salts of the formally D symmetric [Co(en)] (en = ethylenediamine) trication were among the first chiral inorganic compounds to be resolved into enantiomers, the absolute configurations of which are denoted Λ (left handed helix) or Δ (right handed helix). After a >100 year dormant period during which few useful reactions of these substitution inert complexes were described, carbon substituted derivatives have recently been found to be potent catalysts for enantioselective organic synthesis. This review systematically outlines the fascinating range of stereoisomers that can arise, such as conformers associated with the five membered chelate rings (λ/δ), alignment modes of the C-C bonds with the C symmetry axis (lel/ob), geometric isomers (fac/mer), and configurational diastereomers (R/S) arising from carbon stereocenters. These analyses demonstrate a profound stereochemical diversity that can be applied in catalyst optimization. Efforts are made to bridge the often orthogonal nomenclature systems inorganic and organic chemists employ to describe these phenomena.

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The tris[(.+-.)-trans-1,2-cyclohexanediamine]cobalt(III) system

Cited by 58 publications

References 3 publications

Interplay of ligand chirality and metal configuration in mononuclear complexes and in a coordination polymer of Cr(iii)

Interplay of ligand chirality and metal configuration in mononuclear complexes and in a coordination polymer of Cr(iii)

Chiral discrimination in electronic energy transfer between dissymmetric lanthanide(III) and cobalt(III) complexes in solution: effects of ligand size, shape, and configuration in the acceptor complexes

Octahedral Werner complexes with substituted ethylenediamine ligands: a stereochemical primer for a historic series of compounds now emerging as a modern family of catalysts

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