Hydrolytically-sensitive hexaimino and hydrolytically-inert octaamino-cryptand hosts for dicopper

Abstract

The hexa-Schiff-base cryptand N[(CH₂)₂NCH(C₆H₄-m)CHN(CH₂)₂]₃N L¹ has been found to encapsulate a pair of Ag^I or Cu^I cations without hydrolytic attack on the imine bonds; a problem which is evident when the [Cu^II₂(OH)]³⁺ assembly is incorporated. The structure of the dicopper complex of a singly ring-opened ligand, derived from L¹, has been determined. The octaamine cryptand L²(= L¹+ 12H) more easily accommodates a [Cu₂(µ-X)]³⁺ assembly where X = imidazolate, N₃^– or OH^–. Collinear disposition of the bridge with the N_br–N_br axis is confirmed in the first case by an X-ray crystallographic structure determination of the imidazolate-bridged cryptate, and inferred for the second case by spectroscopic and magnetic data, while, for the third case, magnetic susceptibility data indicate severe bending of the Cu–O(H)–Cu assembly.