Structural Characterisation of Cu Complexes of Chiral Ferrocenyl Diphos­phine Ligands

Abstract

Copper complex formation of JosiPhos-type ligands leads to extreme differences in solubility between the racemate and the enantiomers.

Key words

copper complex - chiral ferrocenyl ligand - amplification - solubility

• References

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• 4 Initial spectroscopic studies of enantiopure ferrocenyl ligands were reported in our earlier work: Harutyunyan SR, López F, Browne WR, Correa A, Peña D, Badorrey R, Meetsma A, Minnaard AJ, Feringa BL. J. Am. Chem. Soc. 2006; 128: 9103
• 5 For details see Supporting Information.

Crystal structures of enantiopure CuBr-rev-JosiPhos (CCDC 610500) and CuBr-JosiPhos (CCDC 261573) were published in ref. 4 and in:
• 6a López F, Harutyunyan SR, Meetsma A, Minnaard AJ, Feringa BL. Angew. Chem. Int. Ed. 2005; 44: 2752
• 6b An improved quality crystal structure was obtained for CuBr-rev-JosiPhos (CCDC 909405) during this study.
• 7 CCDC 908802, CCDC 908803, CCDC 908804 and CCDC 909403 contain the supplementary crystallographic data of the corresponding complexes: rac-CuBr-rev-JosiPhos, rac-CuBr-JosiPhos, rac-CuBr-TaniaPhos and enantiopure CuBr-TaniaPhos, presented in this paper. For the crystal structure of enantiopure CuBr-TaniaPhos (CCDC 909403), see Supporting Information.
• 8 Due to the extremely low solubility of the racemic Cu complex of rev-JosiPhos, crystals were obtained by doping one enantiomer in CH₂Cl₂ solution into poly(ethylene oxide) hydrogel followed by addition, as an antisolvent, of a solution of the opposite enantiomer in toluene. See: Choquesillo-Lazarte D, García-Ruiz JM. J. Appl. Cryst. 2011; 44: 172
• 9 The structure of rac-CuBr-rev-JosiPhos is located on an inversion centre: the centrosymmetric dimer is the ‘meso’ form.
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