First example of antimoniated Schiff bases: Hypervalent Sb ← N(sp2) bonds

Abstract

The first example of antimoniated Schiff bases viz. 1-[2-(bis-{2-[(1-R-p-tolylethylimino)methyl]phenyl}stibanyl)benz-E-ilidene]-(1-R-p-tolylethyl)amine (1) and tris[(R)-2-benzyliden-2-yl-amino)butan-1-ol]stibine (2) containing imino groups at the ortho position of aryl ring have been synthesized and characterized. The compounds were obtained by the reaction of tris(o-formylphenyl)stibine with R-4-dimethyl benzyl amine or (R)-2-aminobutan-1-ol, respectively. These chiral antimony based Schiff bases were characterized by IR, mass, 1H, 13C, NMR spectroscopy. The X-ray crystal structures of these two Schiff bases show hypervalent interactions between antimony and sp2 nitrogen atoms. Additionally compound 2 shows intramolecular Sb-O interaction also giving eight-coordination of antimony, both of these observations are uncommon in literature. These two compounds 1 and 2 show helicoidal chirality, which is a very new concept in antimony chemistry. © 2006 Elsevier B.V. All rights reserved.