Interaction of Co(ii), Ni(ii) and Cu(ii) with dibenzo-substituted macrocyclic ligands incorporating both symmetrically and unsymmetrically arranged N, O and S donors

Abstract

The synthesis and characterisation of four 17-membered, dibenzo-substituted macrocyclic ligands incorporating unsymmetrical arrangements of their N 3 S 2 , N 3 O 2 and N 3 OS (two ligands) donor atoms are described; these rings complete the matrix of related macrocyclic systems incorporating both symmetric and unsymmetric donor sets reported previously. The X-ray structures of three of the new macrocycles are reported. In two of the Cu(II) structures only three of the possible five donor atoms present in the corresponding macrocyclic ligand bind to the Cu(II) site, whereas all five donors are coordinated in each of the remaining complexes. The interaction of Co(II), Ni(II) and Cu(II) with the unsymmetric macrocycle series has been investigated by potentiometric (pH) titration in 95% methanol; X-ray structures of two nickel and three copper complexes of these ligands, each exhibiting 1 : 1 (M : L) ratios, have been obtained. The results are discussed in the context of previous results for these metals with the analogous 17-membered ring systems incorporating symmetrical arrangements of their donor atoms, with emphasis being given to both the influence of the donor atom set, as well as the donor atom sequence, on the nature of the resulting complexes.

Comparative investigation of the interaction of Zn(II), Cd(II), Ag(I) and Pb(II) with dibenzo-substituted macrocyclic ligands incorporating both symmetrically and unsymmetrically arranged N, O and S donors: synthetic, solution and X-ray studies

“…[CdL(NO 3 (LH 2 )(NO 3 ) 2 (L ¼ 6, SN/NSN) Zn(NO 3 ) 2 ·6H 2 O (0.0220 g, 0.0740 mmol) in warm EtOH (10 ml) was added to a solution of 6 (0.0195 g, 0.0540 mmol) in warm CH 3 CN (10 ml). Several yellow shard-like crystals of (LH 2 )(NO 3 ) 2 (L ¼ 6) were obtained following slow evaporation of this reaction solution.…”

“…[AgL]PF 6 (L ¼ 4, SN/NNN) AgPF 6 (0.0158 g, 0.0622 mmol) in warm CH 3 CN (5 ml) was added to 4 (0.020 g, 0.0561 mmol) in warm CH 3 with v and c scans to approximately 568 2u at 150(2) K (16). Data integration and reduction were undertaken with SAINT and XPREP (15).…”

“…The synthesis and characterisation of macrocycles 1-18 have been described previously (2,3). Samples for microanalysis were dried over silica gel in vacuum.…”

Macrocyclic coordination chemistry

“…100 A series of 17 membered dibenzo macrocyclic chelators of the type L 65 , with varying N/S/O donor patterns, including unsymmetric arrangements, was synthesised. 101 The X-ray structures of copper(II) and nickel(II) complexes were reported.…”

Synthesis and structural characterization of new N2O2-donor Schiff base macrocycles and their silver(I) coordination polymers

“…However, for this type of applications, due to the nature of the macrocyclic ligands, endo-coordinated macrocyclic complexes (metal ion is bonded inside macrocyclic cavity) are almost exclusively investigated. Considering this type of coordination and donor set atoms (N, O), a large number of investigations were done on unsymmetrical macrocyclic systems [5][6][7], particularly on compartmental macrocycles [8,9]. Another, much less investigated binding mode is the exo-coordination, where the metal ion is linked outside the macrocyclic ring.…”