Zinc amidoisophthalate complexes and their catalytic application in the diastereoselective Henry reaction

Abstract

Reactions of 5-propionamidoisophthalic acid (H₂L1) and 5-benzamidoisophthalic acid (H₂L2) with Zn(NO₃)₂·6H₂O under different hydrothermal conditions lead to two pairs of Zn(II) compounds, viz. the mononuclear [Zn(L1)(H₂O)₃]·H₂O (1) and [Zn(L1)(H₂O)₃]·3H₂O (2), and the 1D polymers [Zn(L2)(H₂O)₂]_n (3) and [{Zn(L2)(H₂O)₂}·2H₂O]_n (4). They crystallize in orthorhombic [Pbca (1) and P2₁2₁2₁ (3)] or triclinic (P, 2 and 4) systems, and their formation depends on the particular reaction conditions. Compounds 1 and 2, as well as 3 and 4, are solvatomorphs, the latter presenting different 1D metal–organic polymeric chains. All of them act as heterogeneous catalysts for the diastereoselective nitroaldol (Henry) reaction of different aldehydes with nitroalkanes and can be recycled without losing activity.