Enantiomeric resolution and X-ray optical activity of a tricobalt extended metal atom chain

Srinivasan, Anandi; Cortijo, Manuel; Bulicanu, Vladimir; Naim, Ahmad; Clérac, Rodolphe; Sainctavit, Philippe; Рогалев, А.; Wilhelm, F.; Hillard, Elizabeth A.

doi:10.1039/c7sc04131d

Cited by 17 publications

(23 citation statements)

References 38 publications

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“…The integrity of the polymeric structures in DMF solution is most likely concentration-dependent with oligomeric and/or monomeric structures being favored under highly dilute conditions, such as those that were employed in these measurements. This accounts for the similar spectra and stability observed for 1 and the corresponding molecular species [29].…”

Section: Circular Dichroism Studiessupporting

confidence: 50%

“…30% in all cases. The maximum expected yield is 50%, given that the clusters are not expected to interconvert in solution [25,26,29,30]. The use of 0.5 or 1 equivalent of (NBu 4 ) 2 2 species, but in lower yields than in the previously-described direct synthesis.…”

Section: Synthesismentioning

confidence: 99%

“…For this purpose, inexpensive chiral dianions based on commercially available (2R, [30]. Furthermore, significant X-ray natural circular dichroism (XNCD) signals were also detected at the Co K-edge in circularly polarized X-ray absorption experiments made on oriented single crystals [29].…”

Section: Introductionmentioning

confidence: 99%

“…In another elegant work, Peng and coworkers were able obtain enantiopure Ni5-based paddlewheel complexes using naphthyridylpyridyldiamine ligands functionalized with bulky chiral groups [28]. Recently, an approach based on anion exchange has been employed by our group to resolve a racemic mixture of [Co3(dpa)4(MeCN)2] 2+ clusters [29]. For this purpose, inexpensive chiral dianions based on commercially available (2R, [30].…”

Section: Introductionmentioning

confidence: 99%

“…ECD measurements in DMF solutions of the two pairs of enantiomers demonstrate the efficiency of the chiral resolution strategy Recently, an approach based on anion exchange has been employed by our group to resolve a racemic mixture of [Co 3 (dpa) 4 (MeCN) 2 ] 2+ clusters [29]. For this purpose, inexpensive chiral dianions based on commercially available (2R,3R)-(+)-or (2S,3S)-(−)-tartaric acid were employed, affording the molecular species [∆-Co 3 (dpa) 4 [30].…”

Section: Introductionmentioning

confidence: 99%

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Enantiopure Chiral Coordination Polymers Based on Polynuclear Paddlewheel Helices and Arsenyl Tartrate

et al. 2018

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Herein, we report the preparation of chiral, one-dimensional coordination polymers based on trinuclear paddlewheel helices [M 3 (dpa) 4 ] 2+ (M = Co(II) and Ni(II); dpa = the anion of 2,2 -dipyridylamine). Enantiomeric resolution of a racemic mixture of [M 3 (dpa) 4 ] 2+ complexes was achieved by chiral recognition of the respective enantiomer by [∆-As 2 (tartrate) 2 ] 2− or [Λ-As 2 (tartrate) 2 ] 2− in N,N-dimethylformamide (DMF), affording crystalline coordination polymers formed from [(∆-Co 3 (dpa) 4 )(Λ-As 2 (tartrate) 2 )]·3DMF (∆-1), [(Λ-Co 3 (dpa) 4 )(∆-As 2 (tartrate) 2 )]·3DMF (Λ-1), [(∆-Ni 3 (dpa) 4 )(Λ-As 2 (tartrate) 2 )]·(4 − n)DMF·nEt 2 O (∆-2) or [(Λ-Ni 3 (dpa) 4 )(∆-As 2 (tartrate) 2 )]·(4 − n)DMF·nEt 2 O (Λ-2) repeating units. UV-visible circular dichroism spectra of the complexes in DMF solutions demonstrate the efficient isolation of optically active species. The helicoidal [M 3 (dpa) 4 ] 2+ units that were obtained display high stability towards racemization as shown by the absence of an evolution of the dichroic signals after several days at room temperature and only a small decrease of the signal after 3 h at 80 • C.

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Section: Circular Dichroism Studiessupporting

confidence: 50%

Section: Synthesismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enantiopure Chiral Coordination Polymers Based on Polynuclear Paddlewheel Helices and Arsenyl Tartrate

et al. 2018

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Coordination Ladder Polymers: Helical Metal Strings

Peng¹,

Lin²,

Chen³

et al. 2023

Ladder Polymers

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Resolution, structures, and vibrational circular dichroism of helicoidal trinickel and tricobalt paddlewheel complexes

et al. 2020

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It has been recently shown that enantiomers of the helicoidal paddlewheel complex [Co3(dpa)4(CH3CN)2] 2+ (dpa = the anion of 2,2'-dipyridylamine) can be resolved using the chiral [As2(tartrate)2] 2− anion (AsT), and that these complexes demonstrate a strong chiroptical response in the UV-visible and X-ray energy regions. Here we report that the nickel congener, [Ni3(dpa)4(CH3CN)2] 2+ , can likewise be resolved using AsT. Depending on the stereochemistry of the enantiopure AsT anion, one or the other of the trinickel enantiomers crystallize from CH3CN and diethyl ether in space group P4212 as the (NBu4)2[Ni3(dpa)4(CH3CN)2](AsT)2•[solvent] salt. After resolution, the AsT salts were converted into the PF6 − salts by anion exchange, with retention of the chirality of the trinickel complex. The enantiopure [Ni3(dpa)4(CH3CN)2](PF6)2•2CH3CN and [Co3(dpa)4(CH3CN)2](PF6)2•CH3CN•C4H10O compounds crystallize in space groups C2 and P21, respectively. Both the Ni(II) and Co(II) complex cations are stable towards racemization in CH3CN. Vibrational circular dichroism (VCD) data obtained in CD3CN demonstrate the expected mirror image spectra for the enantiomers, the observed peaks arising from the dpa ligand. The VCD response is significant, with  values up to 6 Lmol −1 cm −1 and vibrational dissymmetry factors on the order of 10 −3 . DFT calculations well reproduce the experimental spectra, showing little difference between the peak position, sign, and intensity in the VCD for the cobalt and nickel complexes. These results suggest that VCD enhancement of these peaks is unlikely, and their remarkable intensity may be due to their rigid helicoidal structure.

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Enantiomeric resolution and X-ray optical activity of a tricobalt extended metal atom chain

Abstract: Enantiopure single crystals of extended metal atom chains display exceptionally large optical X-ray dichroisms at the Co K-edge.

Cited by 17 publications

References 38 publications

Enantiopure Chiral Coordination Polymers Based on Polynuclear Paddlewheel Helices and Arsenyl Tartrate

Enantiopure Chiral Coordination Polymers Based on Polynuclear Paddlewheel Helices and Arsenyl Tartrate

Coordination Ladder Polymers: Helical Metal Strings

Resolution, structures, and vibrational circular dichroism of helicoidal trinickel and tricobalt paddlewheel complexes

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