Enantiopure Salen‐Type Zinc Complexes

The first structurally characterized salen complexes of zinc having the chiral 1,2‐( R , R )‐diamino‐1,2‐diphenylethane as bridge between the two salicylaldehyde units were prepared. Treatment of ( R,R )‐bis(salicylidene)‐1,2‐diphenylethylenediamine ( 1 ) with ZnEt 2 resulted in the enantiomeric pure salen zinc complex ‐di[( R,R )‐( N,N′ )‐bis(salicylidene)‐1,2‐diphenylethylenediamino)zinc(II)] ( 2 ). Compound 2 is a dimer in the solid state having a Zn‐O‐Zn‐O plane in the center of the molecule. In contrast, reaction of the more bulky ( R,R )‐bis(3,5‐di‐ tert ‐butylsalicylidene)‐1,2‐diphenylethylenediamine ( 3 ) with ZnMe 2 leads to the monomeric compound [( R,R )‐( N,N′ ‐bis(3,5‐di‐ tert ‐butylsalicylidene)‐1,2‐diphenylethylenediamino)(dietylether)zinc(II)] ( 4 ). In addition to the salen ligand one molecule of diethyl ether is bound resulting in a penta‐fold coordinated zinc atom.