A phosphorus-supported multisite coordination ligand containing three imidazolyl arms and its metalation behaviour. An unprecedented co-existence of mononuclear and macrocyclic dinuclear Zn(ii) complexes in the same unit cell of a crystalline lattice

Abstract

The reaction of (S)P[N(Me)NH₂]₃ with three equivalents of 4(5)-imidazolecarboxaldehyde afforded, in situ, (S)P[N(Me)NCHIm]₃ (Im = imidazolyl). The reaction of the latter with metal salts afforded mononuclear complexes [{(S)P[N(Me)NCHIm]₃·M}][X]₂ [M = Co, X = NO₃; M = Ni, X = ClO₄; M = Cd, X = NO₃]. In these compounds, in the cationic part, the metal ion is bound by three imino and three imidazolyl nitrogen atoms to generate a trigonal prismatic type of coordination environment. Structural analysis of the zinc complex showed the presence of a mononuclear [{(S)P[N(Me)NCHIm]₃·Zn}][NO₃]₂ and a dinuclear 20-membered metallamacrocycle [{(S)P[N(Me)NCHIm]₃·Zn}₂][NO₃]₄ in the same unit cell. Solution studies of the zinc complex revealed a monomer–macrocycle equilibrium.