Macrocyclic Schiff bases

Macrocyclic Schiff base compartmental ligands (750) (Robson-type ligands) derived from the [2 + 2] condensation of a 2,6-diformyl- or 2,6-diketo-substituted phenol and a diamine are very prominent in dinuclear Ni coordination chemistry.1901-1903 Particular interest lies in magnetic exchange interactions between the adjacent metal ions as well as in bioinorganic chemistry, where such dinuclear complexes have been proposed as synthetic analogues for bimetallosites. 

Several silver(I) complexes of the macrocyclic Schiff base derived from the [2+2] condensation of terephthalaldehyde and 3-azapentane-1,5-diamine or A,A -bis(3-aminopropyl)methylamine have been described.509,510 The reaction of 2,ll-diaza-difluoro-m-[3,3]-cyclophane with 2,6-bis (bromomethyl)pyridine lead to the 3 + 3 addition product, which gives a complex with two silver... 

In the process of selective synthesis of macrocyclic Schiff bases, derivatives of chiral 1,4-diamines, the H NMR spectra were taken to confirm the synthetic route without 1H signals assignment.20... 

First Synthesis and X-Ray Structural Determination of the Macrocyclic Schiff Base Phosphineamine Complex, Ni([16]dieneN2P2)(PFg)2 0.5 H20... 

Bailey, N. A., Fenton, D. E., Moody, R., etal., Complexes of ligands providing endogenous bridges A. copper(II) complexes of macrocyclic Schiff-bases derived from 2,6-diacetylpyridine and l,N-diamino-N -hydroxyalkanes (N,N = 3,2 - 4,2 - and 5,3) - synthesis, properties, and structures. J. Chem. Soc., Dalton Trans. 1987, 2519-2529. 

Figure 2. Experimental (A isomer) and computed (A isomer) low energy structures of the dicopper(I) complex of the macrocyclic Schiff-base ligand with para-xylylene spacer groups, and computed energy barrier (confirmed by NMR spectroscopy).125126...

Kasahara, K. and Endo, M. (2001) Solvent extraction of metal ions with acyclic and macrocyclic Schiff bases, Anal. Sci, 17(Suppl.), a339-a342. 

Fujiwara, M., Nakajima, Y., Matsushita, T., and Shono, T. (1985) Preparation and characterization of copper(II) and nickel(II) complexes with novel tetraaza-macrocyclic Schiff bases, Polyhedron, 4(9), 1589-1594. 

The examined compound behaves as an N,Te-donor ligand also in analogous cobalt and copper complexes [922]. The N,Te-ligand environment is very likely for complexes 530 [923], 531 [924], adduct 532 [925], and tellurium-containing macrocyclic Schiff bases 533 [926] ... 

The macrocyclic Schiff base 5,9,14,18-tetramethyl-l,4,10,13-tetraazacyclo-octadeca-5,8,14,17-tetraene-7,16-dione (I) (H4daen) can serve as a precursor to the formation of either mononuclear macrocyclic complexes or mononuclear acyclic complexes, depending on the reaction conditions. The mononuclear complexes may then be used in the synthesis of homo- or heterobinuclear complexes. The synthetic procedures described have been extended to include Schiff bases derived from a range of symmetrical and nonsymmetrical tri-... 

Fig. 4.13. Structure of the dimetallic gadolinium complex with a ditopic macrocyclic Schiff base, [Gd2(L2 )(N03)4], Redrawn from I.A. Kahwa et al., J. Chem. Soc., Chem. Coramun. 1531, 1989.

In this section complexes of acyclic Schiff base ligands only are considered, macrocyclic Schiff base complexes are included in a later section. 

---