Compartmental ligands. Part 3. Homo- and hetero-binuclear transition-metal complexes of acyclic Schiff bases derived from 1,3,5-triketones

Abstract

Acyclic Schiff bases derived from 1,3,5-triketones and α,ω-alkanediamines have two ligand compartments for metal co-ordination, one based on N₂O₂, and the other on O₂O₂ donor sets. Homo- and hetero-binuclear metal complexes of such ligands have been prepared and the nature of the site occupancy investigated. The mononuclear complexes [6,11-dimethyl-7,10-diazahexadeca-5, 11-diene-2,4,13,15-tetraonato(2–)-N⁷N¹⁰O⁴O¹³]copper(II)(5a; M = Cu) and 5,10-dimethyl-1,14-diphenyl-6,9-diazatetradeca-4,10-diene-1,3,12,14-tetraonato(2–)-N⁶N⁹O³O¹²] copper(II)(5m; M = Cu) have been treated with various metal (II) acetates to give Cu₂, Ni₂, CuUO₂, CuVO, CuZn, NiCu, NiUO₂, NiVO, and NiZn derivatives. The first named metal is retained in the N₂O₂ compartment of the ligand, whilst the second occupies the O₂O₂ compartment. The pattern of incorporation, and the purity of the binuclear species, have been established by i.r., diffuse-reflectance, and mass spectra and room-temperature magnetic-moment studies. Several dicopper(II) complexes of a range of aliphatic and phenyl-substituted acyclic Schlff bases have also been prepared.