Lanthanide metal complexes of N,N′-ethylenebis(pyridin-2-one);: from chelates to metallacyclic frameworks

The ligand N,N'-ethylenebis(pyridin-2-one) (EBP) forms a range of lanthanide (Ln) complexes of types Ln(EBP)(2)(NO3)(3) (Ln = La-Gd), Ln(2)(EBP)(3)(NO3)(6) . 2MeOH (Ln = Gd-Yb and also Y), Ln(2)(EBP)(3)(NO3)(6) . nMeCN (Ln = Tb-Yb), representative members of which have been studied by single crystal X-ray diffraction. Crystals of Eu(EBP)(2)(NO3)(3) are monoclinic, space group C2/c, a = 20.583(3), b = 9.453(2), c = 17.006(2) Angstrom, beta = 120.58(2)degrees Z = 4. The compound is mononuclear with each Eu centre having a coordination environment comprising three chelating nitrates and two nine-membered chelate rings formed by the EBP ligands. Crystals of Tb-2(EBP)(3)(NO3)(6) . 5MeCN are triclinic, space group P (1) over bar, a = 10.504(5), b = 10.856(4), c = 17.145(6) Angstrom, alpha = 84.23(2), beta = 72.68(2), gamma = 72.79(2)degrees, Z = 2. The EBP ligands bridge the Tb centres forming sheets of contiguous 54-membered rings. The MeCN molecules of solvation are occluded within the lattice, some lying within the metallamacrocyclic rings and some between the sheets. Crystals of {[Ho(EBP)(2)(MeOH)(NO3)(3)]0.5(EBP)](n) are triclinic, space group P (1) over bar, a = 8.316(2), b = 10.138(2), c = 15.441(3) Angstrom, alpha = 92.82(2), beta = 92.29(2), gamma = 102.99(2)degrees, Z = 2. Each Ho atom is coordinated to three chelating nitrate groups, two bridging EBP ligands and one methanol molecule leading to the formation of polymeric chains [Ho(EBP)(2)(MeOH)(NO3)(3)](n). The remaining EBP molecules are non-coordinated but form hydrogen bonds to the methanol ligands and thereby link adjacent chains to form sheets of contiguous 78-membered rings. (C) 1998 Elsevier Science S.A. All rights reserved.