Use of azido ligands in the syntheses of different homo- and hetero-complexes
Résumé
The reaction of neutral “half-unit” copper azido complexes, made of “half-unit ligands” resulting from a monocondensation of different diamines with an aldehyde function and of end-on azido ligands, with diverse gadolinium or sodium salts, is not straightforward. The resulting complexes are mainly homodinuclear copper complexes. Heterodinuclear Cu–Gd complexes devoid of azido bridges necessitate use of gadolinium nitrate or gadolinium hexafluoroacetylacetonate. A heterotrinuclear Cu–Na–Cu by-product in which the Cu and Na ions are linked by double phenoxo-end-on azido bridges has also been structurally characterized. The decrease of the acidic character of positive ions in protic solvents in going from naked gadolinium to gadolinium nitrate, gadolinium complex and to sodium ions can explain the diverse reaction pathways and formation of the different final products.