Zusammenfassung
The ruthenium compound [(Cy)Ru(LL*)Cl] (1) crystallizes as a 1:1 mixture of the two diastereomers (R-Ru,S-C)-1 and (S-Ru,Sc)-1 in the same single crystal, whereas the corresponding osmium compound [(Cy)Os(LL*)Cl] (2), almost identical to 1 in the molecular parameters, crystallizes as the pure diastereomer (R-Os,S-C)-2. 1:1 diastereomer co-crystallization is traced back to a molecular recognition ...
Zusammenfassung
The ruthenium compound [(Cy)Ru(LL*)Cl] (1) crystallizes as a 1:1 mixture of the two diastereomers (R-Ru,S-C)-1 and (S-Ru,Sc)-1 in the same single crystal, whereas the corresponding osmium compound [(Cy)Os(LL*)Cl] (2), almost identical to 1 in the molecular parameters, crystallizes as the pure diastereomer (R-Os,S-C)-2. 1:1 diastereomer co-crystallization is traced back to a molecular recognition motif, the pair formation of fragments (Ar)MXY, in which X and Y are electronegative substituents. Thus, compounds of the type [(Ar)MXYZ], in particular (Cy)Ru derivatives, tend to form inversion pairs of enantiomers and also of diastereomers. Fifteen cases of 1:1 diastereomer co-crystallization in half-sandwich complexes are presented. The discussion is extended to [(Cy)RuLCl2] and related complexes. It is shown that there is a delicate balance between 1:1 diastereomer co-crystallization and crystallization as a pure diastereomer. (C) 2003 Elsevier B.V. All rights reserved.
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