A family of fourteen soluble stable macrocyclic [Ni II3LnIII] heterometallic 3d–4f complexes

Abstract

A family of fourteen tetranuclear, 3d–4f heterometallic nickel(II)–lanthanide(III) complexes of the hexaimine macrocycle (L^Pr)⁶⁻, with general formula Ni^II₃Ln^III(L^Pr)(NO₃)₃·xsolvents (Ln^III = La^III, Ce^III, Pr^III, Nd^III, Sm^III, Eu^III, Gd^III, Tb^III, Dy^III, Ho^III, Er^III, Tm^III, Yb^III or Lu^III), were prepared in a one-pot synthesis using a 3 : 1 : 3 : 3 reaction of nickel(II) acetate, the appropriate lanthanide(III) nitrate, the dialdehyde 1,4-diformyl-2,3-dihydroxybenzene (H₂L^Ald) and 1,3-diaminopropane. In addition, three tetranuclear heterometallic nickel(II)–lanthanide(III) complexes of H₂L^Ald, with general formula Ni^II₃Ln^III(L^Ald)₃(NO₃)₃·xsolvents, were deliberately prepared (Ln^III = La^III, Dy^III or Yb^III) as in effect they represent intermediates en route to the above macrocyclic complexes. Whilst single crystals of the macrocyclic complexes were not forthcoming, X-ray crystal structure determinations on Ni^II₃Ln^III(L^Ald)₃(NO₃)₃·xsolvents (Ln^III = Dy^III or Yb^III) confirmed that the large ten-coordinate lanthanide(III) ion is bound in the central O₆ pocket while the smaller six-coordinate nickel(II) ions are bound in the outer O₄ pockets. In all fourteen cases, addition of the diamine to this intermediate (all in one pot) gives the tetrametallic [3 + 3] macrocyclic product. The magnetic properties of all fourteen macrocyclic complexes were measured down to 1.8 K to check for Single-Molecule Magnet behaviour, but no slow dynamics of magnetisation was observed.