Efficient Resolution of a Dinuclear Triple Helicate by Asymmetric Extraction/Precipitation with TRISPHAT Anions as Resolving Agents

Jodry, Jonathan J.; Lacour, Jérôme

doi:10.1002/1521-3765(20001201)6:23<4297::aid-chem4297>3.0.co;2-#

Cited by 57 publications

(42 citation statements)

References 61 publications

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“…Selectivity ratios as high as 49 : 1 were measured for the enantiomers of the cations in the organic and aqueous layers, demonstrating without ambiguity the efficiency of the resolution procedure 25. An extension of this protocol was further developed for diiron(II) triple helicate 30 and afforded in separated phases the P or M enantiomers of the [Fe 2 L 3 ] 4+ helix (see Scheme ) 26…”

Section: Efficient Resolving Agentsmentioning

confidence: 97%

Hexacoordinated phosphates: how to teach old chiral anions new asymmetric tricks

Lacour

Linder

2007

The Chemical Record

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Chemical reactions and processes often involve chiral, yet racemic, cationic reagents, intermediates, or products. To afford instead nonracemic or enantiopure compounds, an asymmetric ion pairing of the cations with enantiopure anions can be considered—the counter ions behaving as asymmetric auxiliaries, ligands, or reagents. Detailed herein is a short review of our approach toward gaining reliable and predictable control over stereoselective ion pairing phenomena through the synthesis and use of novel configurationally stable hexacoordinated phosphate anions. © 2007 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 7: 275–285; 2007: Published online in Wiley InterScience (http://www.interscience.wiley.com) DOI 10.1002/tcr.20124

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Section: Efficient Resolving Agentsmentioning

confidence: 97%

Hexacoordinated phosphates: how to teach old chiral anions new asymmetric tricks

Lacour

Linder

2007

The Chemical Record

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“…In the case of the Ag 3 1 2 ⋅( Δ ‐TRISPHAT) 3 complex, the P ⇌ M flip motion readily takes place even at 303 K. The signals for Ag 3 1 2 ⋅( Δ ‐TRISPHAT) 3 in [D 6 ]acetone/CDCl 3 (2:1) did not split at all into two sets for the P and M isomers (Figure 4 c). On the other hand, upon cooling the sample to 253 K, two sets of signals for H a , H b , and one of the p ‐tolyl protons appeared in a 7:6 ratio with low chiral induction;14 these signals correspond to the ( P )‐ and ( M )‐Ag 3 1 2 ⋅( Δ ‐TRISPHAT) 3 complexes (Figure 4 d). 15 Thus, the Ag 3 1 2 complex can flip between the P and M forms rapidly on the NMR timescale even at 303 K. The differences found in the dynamic features of the Ag 3 1 2 and Ag 3 2 2 complexes probably arise from the difference in the size of the ligands attached to the central aromatic ring.…”

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confidence: 99%

Quantitative Formation of Sandwich‐Shaped Trinuclear Silver(I) Complexes and Dynamic Nature of Their P⇌M Flip Motion in Solution

et al. 2003

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There has been much interest in developing artificial helical structures by synthetic oligomers [1] or metal-ligand complexes [2] closely related to those present in natural biomolecules such as DNA and proteins. In general, helical structures potentially undergo molecular motions such as folding [3] and PÐM conversion. [4,5] The PÐM conversion is well-known in natural systems, for example, the dynamic behavior of DNA helices between the right-handed B and left-handed Z forms.[6] Such PÐM dynamic processes are currently attracting considerable attention from a viewpoint of the development of molecular machines. [7] Our strategy reported herein is directed toward the flip motion of the helical structures of trinuclear Ag 3 L 2 complexes with disk-shaped ligands that bear three coordination sites ( Figure 1). The ligands contain three monodentate ligands and three p-tolyl groups attached to the central benzene ring; the three p-tolyl groups are introduced to force the neighboring flat metal ligands out of the plane of the central aromatic ring. Such ligands self-assemble to form sandwich-shaped architectures with appropriate metal ions (e.g. Ag + ) favoring linear coordination geometry.[8] For example, in the Ag 3 L 2 complexes, all the exterior rings should tilt in the same direction and result in the formation of helical structures with P and M geometries, between which flip motions may take place and allow the ring rotation with retention of the coordination bonds. Herein we describe the quantitative formation of sandwich-shaped trinuclear Ag + complexes with two disk-shaped ligands that bear three thiazolyl (1) or 2-pyridyl groups (2) as the coordination sites. The helical structure of the resulting entity Ag 3 1 2 was determined by Xray single-crystal analysis, and variable-temperature 1 H NMR measurements revealed that the dynamic behavior (i.e. PÐM flip motion) of these complexes is remarkably affected by the ring size of the ligands attached to the central benzene ring.Evidence for the formation of sandwich-shaped Ag + complexes from a mixture of tridentate ligands 1 or 2 [9] and AgOTf (2:3) in CHCl 3 /CH 3 OH was obtained by electrospray ionization time-of-flight (ESI TOF) mass spectrometry.[10]The ESI mass spectrum of a mixture of 1 and AgOTf (1/ AgOTf 2:3) exhibited a main peak at m/z 777.2, which is attributed to cationic [Ag 3 1 2 ·(OH)·(H 2 O)] 2+ . Similarly, the spectrum of a mixture of 2 and AgOTf (2/AgOTf 2:3) showed a main peak at m/z 759.4, which corresponds to [Ag 3 2 2 ·(OH)·(H 2 O)] 2+ . These data indicate that trinuclear Ag 3 1 2 and Ag 3 2 2 complexes were formed in solution.The 1 H NMR spectrum of a mixture of 1 and AgOTf (2:3) in CDCl 3 /CD 3 OD (1:1) was highly symmetrical except for the

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“…65 This structure is reproduced in Figure 5.17c. These helicates are more stable toward racemization than the analogous tris(bpy) complexes in isolated metal center structures.…”

Section: Square Planarmentioning

confidence: 72%

Absolute Chiral Structures of Inorganic Compounds

Riehl

Kaizaki

2010

Physical Inorganic Chemistry

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Chiral inorganic compounds play increasingly important roles in current research efforts concerned with asymmetric catalysis, biochemistry, and supramolecular chemistry. Although our ability to determine precise chiral structures of inorganic compounds and relate these structures to chemical phenomena is a relatively recent achievement, this area of research has been a central and fundamental subject since the beginning of modern chemistry. The realization that substances other than those containing tetrahedral carbon atoms could occur as nonsuperimposable mirrorimage forms was first made by the "father of coordination chemistry" Alfred Werner at the end of the nineteenth century. 1 A critical consequence of his octahedral coordination theory was that certain isomers of six-coordinate metal complexes should exist as enantiomeric pairs. As early as 1897, Werner was speculating on whether or not he could verify the existence of mirror-image compounds from sixcoordinate octahedral geometry, and the preparation and resolution of a chiral molecular metal complex was finally achieved by his research colleagues Ernst Scholze and Victor L. King with the publication of the separation of the optical isomers (enantiomers) of cis-bromoamminebis(ethylenediamine)cobalt(III) salts in 1911. 2 Figure 5.1 illustrates the structure of the two possible mirror-image structures for this complex. The separated complexes were shown to possess equal and opposite optical rotations (OR) confirming their mirror-image relationship. Alfred Werner received the Nobel Prize in Chemistry for his development of the coordination theory 2 years after the publication of this milestone work in 1913.Following the experimental results of Werner and his colleagues, a number of theoretical attempts were made to correlate the sign and magnitude of the optical rotation to the exact chiral molecular structure of metal complexes. These approaches have been summarized by Richardson. 3 The term "absolute structure" is sometimes limited to a discussion of the structure of noncentrosymmetric crystals, and the term Physical Inorganic Chemistry: Principles, Methods, and Models Edited by Andreja Bakac

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Efficient Resolution of a Dinuclear Triple Helicate by Asymmetric Extraction/Precipitation with TRISPHAT Anions as Resolving Agents

Cited by 57 publications

References 61 publications

Hexacoordinated phosphates: how to teach old chiral anions new asymmetric tricks

Hexacoordinated phosphates: how to teach old chiral anions new asymmetric tricks

Quantitative Formation of Sandwich‐Shaped Trinuclear Silver(I) Complexes and Dynamic Nature of Their P⇌M Flip Motion in Solution

Absolute Chiral Structures of Inorganic Compounds

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