Copper complexes of polyazacryptands.

Lu, Qin (1999). Copper complexes of polyazacryptands. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000ff3d

Abstract

Dicopper complexes of L1-L5, which are obtained from [2+3] condensation of tris-(2-aminoethyl)amine with a series of dialdehydes, have been synthesized. X-ray structure determination has been carried on [Cu₂L1]O₃SCF₃]₂, [Cu₂L2][BF₄]₂, [Cu₂L4][ClO₄]₂, and [Cu<2(L5-3H)]C104. NMR spectra of dicopper(I) complexes of L1-L5 indicate that all the ligands adopt a convergent conformation upon encapsulating a pair of Cu(I) ions. Cyclic voltammetry studies reveal that dicopper(I) complexes in this series are stable either thermodynamically or Idnetically under aerobic conditions. Dicopper(II) complexes are hydrolytically sensitive and ring-opening reactions occur followed by the hydrolytic attack on the imino C=N double bond(s).
Octaamino cryptands RL-RL5 have been synthesized through hydrogenation of L1-L5 with NaBH₄. They are good hosts for a pair of Cu(II) ions whereas their dicopper(I) complexes are air-sensitive. Three type of bridging ligands, OH^-, im^-, and N₃^-, are incorporated into the dicopper(II) cryptâtes and their structural, spectroscopic, and magnetic properties have been investigated. Variable temperature magnetic susceptibility studies combined with X-ray crystallography and EPR spectroscopy demonstrate the effect of unusually large bridge angle, such as collinear Cu-0(H)-Cu or Cu-N=N=N-Cu linkage, on the magnetic exchange between the two Cu(II) ions in the bridged dicopper(H) cryptates.