Co‐Crystallization of Half‐Sandwich (R_M,R_C)/(S_M,R_C) Diastereomers in Single Crystals

Abstract

Diastereomer separation by fractional crystallization is the most important method for the resolution of enantiomers in research as well as in industry. Herein we describe two different types of diastereomer co-crystallization, which impede diastereomer separation. The two diastereomers (R Fe ,R C )-and (S Fe ,R C )-[CpFe(Prophos)PPh(OMe) 2 ]PF 6 , differing only in the metal atom configuration, form 1:1 co-crystals with a racematelike lattice. Between the (R Fe ,R C ) and (S Fe ,R C ) diastereomers there is an "almost"-inversion center and the (R Fe ,R C )/(S Fe ,R C ) pair repeats as a kind of "dimer" in the lattice. Crystallization of a [a] General: 1 H/ 13 C/ 31 P{ 1 H} NMR: Bruker Avance 400 (400/125/ 162 MHz), TMS as internal standard and H 3 PO 4 as external standard. MS: Agilent Q-TOF 6540 UHD or ThermoQuest Finnigan TSQ 7000. All manipulations were carried out under purified nitrogen. All solvents were dried and distilled before use according to standard procedures. (R)-Prophos and PPh(OMe) 2 were purchased from Wako Pure Chem. Ind. Ltd. (R Fe ,R C )/(S Fe ,R C )-(η 5 -Cyclopentadienyl)[propane-1,2-diylbis(diphenylphosphane-κP)[dimethoxy(phenyl)phosphane-κP]iron Eur. J. Inorg. Chem. 2016, 5405-5410 www.eurjic.org