A Novel Salicylate-Based Macrobicycle with a “Split Personality”
- 15 September 1999
- journal article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 38 (20) , 4522-4529
- https://doi.org/10.1021/ic990411k
Abstract
Two new ligands (the tripodal TRENIAM and macrobicyclic TRENSAM) which use 2-hydroxyisophthalic acid as a salicylato-type of binding group have been prepared, and their coordination chemistry has been investigated. The structures of several metal complexes have been determined in both solution and the solid state. The ferric and gallium complexes of TRENIAM are isostructural and crystallize in the triclinic space group P1̄, with Z = 4. For Fe[TRENIAM]: a = 12.0203(4) Å, b = 12.6996(4) Å, c = 24.6435(8) Å, α = 83.146(1)°, β = 88.531(1)°, γ = 85.282(1)°. For Ga[TRENIAM]: a = 11.9780(2) Å, b = 12.6417(3) Å, c = 24.5404(6) Å, α = 83.324(1)°, β = 88.488(1)°, γ = 85.038(1)°. The metal cations are bound by three phenolic oxygens and three carbonyl oxygens in a ligand structure analogous to that of salicylamide. The ferric and gallium complexes of macrobicyclic TRENSAM are essentially isosteric and crystallize in the monoclinic space group P21/n, with Z = 4. For Fe[macrobicyclic TRENSAM]+: a = 10.7156(2) Å, b = 23.10490(10) Å, c = 19.8373(3) Å, β = 98.829(1)°. For Ga[macrobicyclic TRENSAM]+: a = 11.1144(2) Å, b = 22.8382(4) Å, c = 19.4525(4) Å, β = 99.247(1)°. The metal complexes of macrobicyclic TRENSAM impose an unusual conformational distortion on the macrobicycle, breaking the C2 symmetry axis of the parent ligand. This results in a macrocyclic complex with two acyclic analogues, TRENSAM and TRENIAM, giving the cryptate a “split personality” with structural features of both acyclic ligands. 1H NMR shows that the metal complexes of macrobicyclic TRENSAM are kinetically inert and retain an asymmetric structure in solution. Cyclic voltammetry experiments show that the ferrous complexes are strongly stabilized by the macrocyclic structure.Keywords
This publication has 28 references indexed in Scilit:
- Structural Characterization of a Tris-salicylate Coordination for Iron(III) with the Tripodal Ligand O-TRENSOXInorganic Chemistry, 1999
- Enterobactin Protonation and Iron Release: Hexadentate Tris-Salicylate Ligands as Models for Triprotonated Ferric Enterobactin1Journal of the American Chemical Society, 1998
- O-TRENSOX, a New Tripodal Iron Chelator Based on 8-Hydroxyquinoline Subunits: Thermodynamic and Kinetic StudiesInorganic Chemistry, 1997
- Synthesis of salicylamide and bipyridine containing ligands for iron(II) and iron(III) coordinationTetrahedron, 1996
- O-TRENSOX: A Promising Water-Soluble Iron Chelator (Both FeIII and FeII) Potentially Suitable for Plant Nutrition and Iron Chelation TherapyJournal of the American Chemical Society, 1995
- Coordination chemistry of microbial iron transport. 49. The vanadium(IV) enterobactin complex: structural, spectroscopic, and electrochemical characterizationJournal of the American Chemical Society, 1993
- The salicylate mode of bonding in protonated ferric enterobactin analogsJournal of the American Chemical Society, 1989
- Coordination chemistry of microbial iron transport compounds. 23. Fourier transform infrared spectroscopy of ferric catechoylamide analogues of enterobactinJournal of the American Chemical Society, 1983
- Coordination chemistry of microbial iron transport compounds. 22. pH-dependent Moessbauer spectroscopy of ferric enterobactin and synthetic analoguesJournal of the American Chemical Society, 1983
- Coordination chemistry of microbial iron transport compounds. 19. Stability constants and electrochemical behavior of ferric enterobactin and model complexesJournal of the American Chemical Society, 1979