Dinucleating Schiff base ligand in Zn/4f coordination chemistry: synthetic challenges and catalytic activity evaluation

Abstract

Four Zn/4f polynuclear coordination clusters (PCCs) formulated as [Zn^II₂Dy^III₂L₂(CO₃)₂(NO₃)₂] (1), [Zn^IIY^IIIL(NO₃)₂(o-van) (MeOH)] (MeOH) [2 (MeOH)] and [Zn^IILn^IIIL(NO₃)₂Cl(EtOH)] where Ln is Dy (3) and Y (4) and where H₂L is the dinucleating Schiff base ligand N,N′-bis(3-methoxysalicylidene)cyclohexane-1,2-diamine and o-van is ortho-vanillin, were prepared and fully characterised for the first time. These air-stable heterometallic PCCs, obtained in high yields from commercially available materials, were shown to remain stable in solution in their dinuclear [Zn^IILn^IIIL] form. Their catalytic activity was evaluated in various catalytic transformations including the Friedel–Crafts alkylation of 2-acyl imidazoles with indoles.