Dicopper(II) Complexes with the Enantiomers of a Bidentate Chiral Reduced Schiff Base: Inclusion of Chlorinated Solvents and Chiral Recognition of1,2‐Dichloroethane Rotamers in the Crystal Lattice

Bisphenoxo‐bridged dicopper(II) complexes [Cu 2 L n 2 Cl 2 ] { 1 ( n = 1) and 2 ( n = 2)} with the N,O‐donor reduced Schiff bases N ‐(2‐hydroxybenzyl)‐( R )‐α‐methylbenzylamine (HL 1 ) and N ‐(2‐hydroxybenzyl)‐( S )‐α‐methylbenzylamine (HL 2 ) have been synthesised and characterised. In both 1 and 2 , the bidentate chiral ligands coordinate the metal centres through the secondary amine N atom and the bridging phenolate O atom. The chloride ion occupies the fourth coordination site and completes a slightly distorted square‐planar NO 2 Cl environment around each copper(II) centre. Magnetic susceptibility measurements in the solid state suggest a strong antiferromagnetic interaction between the metal centres in both complexes. Both 1 and 2 readily form 1:1 host‐guest compounds with chlorinated solvents such as CH 2 Cl 2 , CHCl 3 and Cl(CH 2 ) 2 Cl. All the host‐guest compounds crystallise in noncentrosymmetric space groups. 1· CH 2 Cl 2 and 2· CH 2 Cl 2 crystallise in the P 2 1 space group while 1· CHCl 3 , 2· CHCl 3 , 1· Cl(CH 2 ) 2 Cl and 2· Cl(CH 2 ) 2 Cl crystallise in the P 2 1 2 1 2 1 space group. In these inclusion crystals, the C–H ··· Cl interactions between the guest and the host molecules are primarily responsible for enclatheration of the chloroalkane molecules. In the case of CH 2 Cl 2 , one of its Cl atoms acts as the acceptor. On the other hand, for CHCl 3 and Cl(CH 2 ) 2 Cl, the metal coordinated Cl atom of the host complex acts as the acceptor. The structures of 1· ( P )‐Cl(CH 2 ) 2 Cl and 2· ( M )‐Cl(CH 2 ) 2 Cl provide rare examples for chiral recognition of the right handed ( P ) and the left handed ( M ) gauche forms of Cl(CH 2 ) 2 Cl in molecular assemblies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)