Design of base metal extractants. Part 1. Inter-ligand hydrogen bonding in the assembly of pseudo-macrocyclic bis(aminosulfonamidato)M(ii) complexes

Abstract

Monosulfonyl derivatives of simple 1,2- and 1,3-diamines (R2HN-R-NHSO2R1 = L) have been shown to be easily deprotonated to give neutral 2:1 complexes, [M(L - H)(2)], with Co(II), Ni(II), Cu(II) or Zn(II). The Ni(II) and Cu(II) complexes with deprotonated N-tosyl-1,2-diaminoethane have a planar N4(2-) donor set and a 14-membered pseudo-macrocyclic structure based on head-to-tail S=O...H-N((amine)) bonding between the two bidentate ligands. In the related tetrahedral Zn(II) complex the ends of the mutually perpendicular bidentate N2- units are too far apart to form a cyclic H-bonded system. X-Ray structure determinations on five free ligands provide evidence for extensive inter-molecular H-bonding, which in the case of N-tosyl-1,3-diaminopropane and its N'-tert-butyl derivative involves formation of dimeric 16-membered pseudo-macrocycles. Despite favourable inter-ligand H-bonding in the neutral 2:1 complexes, these ligands are relatively weak extractants, showing >50% loading of Cu(II) in "pH-swing" equilibria, 2L(org)+ M2+ = [M(L - H)2](org)+ 2 H+, only when the pH of the aqueous phase is raised above 4.

Transition metal salts dependent intramolecular cyclization of a diimine

“…N-Tosyl-ethylenediamine was synthesized from the reaction of ethylenediamine with 4-toluene sulfonyl chloride according to a literature method [20,21]. The reaction of N-tosyl-ethylenediamine with benzil in ethanol at 90°C gave L 1 in a yield of 70% after recrystallization from ethanol.…”

Synthesis and crystal structures of a poliaza receptor macrigiland: 1,3-BTS(2-Nitrobenzyldenamino)Propan-2-0L

“…The polydentate azamacroligands have been of considerable interest in terms of structure chemistry, affinity with heavy metals and environmental and technological applications [5][6][7][8]. During the past years an extensive work has been carried out in the synthesis of this type of compounds which has culminated in the production of materials used in the extraction of heavy metals, as a catalyst, in the construction of diodes and molecular memories [9][10][11] is why the importance of both its synthesis as determining its structure on this applications can predict.…”

Synthesis and structure of para‐toluene sulfonamide lanthanide complexes and their application in the polymerization of ε‐caprolactone

“…Sulfonamide compounds have been widely used in organometallic chemistry, such as p‐toluene sulfonyl amino acid ligands, p‐toluene sulfonamide ligands, p‐toluene sulfonic acid schiff base ligands . Researches on complexes prepared of these ligands and transition metals show that these ligands have strong capabilities of coordination and multiple form of coordination.…”