Asymmetric compartmental macrocyclic ligands and related mononuclear and hetero-dinuclear complexes with d- and/or f-metal ions

Abstract

[1+1] Asymmetric compartmental macrocycles H 2L (H 2L A–H 2L G), containing one N 2O 2, N 3O 2 or N 2O 2O 2 Schiff base and one adjacent O 2O 3, O 2O 4 or O 2O 5 ‘crown like’ coordination chamber, have been prepared by self-condensation or by reaction of the appropriate diformyl (H 2L I–H 2L III) and amine precursors in the presence of barium(II) salts, followed by a demetallation reaction of the resulting complexes, Ba(H 2L)(ClO 4) 2, with guanidinium sulphate. They have been characterised by IR, NMR and mass spectrometry. The single crystal X-ray structural determination of H 2L C confirms their [1+1] cyclic nature. The mononuclear complexes Ln(H 2L)(X) 3· nS (Ln=La-Lu; X=Cl −, NO 3 −) and Ni(L)· nS have been prepared by reaction of the preformed ligands with the appropriate metal salt, by template procedure or by condensation of the acyclic complexes with the diformyl derivatives Ln(H 2L′)(X) 3 or Ni(L′) with the appropriate amine. They have been characterised by IR, NMR, magnetic susceptibility and mass spectrometry. In these mononuclear complexes the 4f and transition metal ion invariantly occupy respectively, the crown-like and the Schiff base chamber. In [La(H 2L C)(H 2O) 4]Cl 3 the single crystal X-ray structure reveals that a bicapped square antiprismatic decacoordination about the central metal ion is reached by the coordination of the oxygen atoms of the crown-ether chamber and by the oxygen atoms of four water molecules. A Schiff base occupancy has been obtained by the lanthanum ion only when Ba(H 2L)(ClO 4) 2 was used instead of the free ligand H 2L: the barium ion remains in the crown-ether chamber and obliges the incoming lanthanum ion to fill the Schiff base site. By this procedure the hetero-dinuclear complex, LaBa(L D)(ClO 4) 2(OH)·3H 2O, has been obtained. La(H 2L C)(Cl) 3, by reaction with the appropriate metal salt, gives rise to the hetero-dinuclear species MLa(L C)(Cl) 2(OH)· nH 2O (M=Cu, n=1; M=Ni, n=2). LaNa(L D)(X) 2·(X=Cl, NO 3) and LaNa(L F)(NO 3) 2 have been synthesised by template procedure or by reaction of H 2L D or H 2L F with the appropriate lanthanum(III) salt and sodium hydroxide.