The use of hydrogenated Schiff base ligands in the synthesis of multi-metallic compounds II

Tris(2-hydroxybenzylaminoethyl)amine (H₃L) complexes of nickel, copper and zinc are investigated as potential metallo-ligands ([(H_xL)M]; x = 0, 1: M = Ni, Cu, Zn). The homometallic complexes formed are dimetallic ([{(HL)Ni}Ni(OAc)₂] and [{(L)Zn}ZnCl]), tetrametallic ([{(L)Cu}Cu]₂²⁺) and hexametallic ([{(L)Ni}Ni₂(μ-OH)₂(OEt)(OH₂)]₂). Hetero-dimetallic complexes can be formed with [(HL)Ni] and copper chloride ([{(HL)Ni}CuCl₂]) or zinc bromide ([{(HL)Ni}ZnBr₂]). The metallo-ligand acts as a chelating agent using phenolate pairs. The remaining phenolate either does not coordinate or can be used to increase the number of metals included in the scaffold from two to four or six. Not all combinations are possible and [(HL)Cu]⁺ produces a charge separated species with zinc chloride rather than a complex. An exchange reaction is observed to take place when [(HL)Zn]⁺ is treated with the halides of nickel or copper producing [(HL)M]⁺ (M = Ni, Cu, respectively).