Article

Russian Journal of Coordination Chemistry

, Volume 31, Issue 11, pp 768-774

First online:

Sc(III), Eu(III), and Gd(III) Complexes with Macrocyclic Cavitand Cucurbit[6]uril: Synthesis and Crystal Structures

  • A. A. TripolskayaAffiliated withInstitute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences
  • , E. A. MainichevaAffiliated withInstitute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences
  • , T. V. Mit'kinaAffiliated withInstitute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences
  • , O. A. Geras'koAffiliated withInstitute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences
  • , D. Yu. NaumovAffiliated withInstitute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences
  • , V. P. FedinAffiliated withInstitute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences

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Abstract

Slow evaporation of solutions of Sc and Eu nitrates with macrocyclic cavitand cucurbit[6]uril gives crystals of isostructural complexes [Sc(NO3)(H2O)4(C36H36N24O12)](NO3)2 ⋅ 8.5H2O (space group Pna21, a = 32.0065(18) Å, b = 14.7904(8) Å, c = 11.5774(6) Å, V = 5480.6(5) Å3, Z = 4) and [Eu(NO3)(H2O)4(C36H36N24O12)](NO3)2 ⋅ 6.75H2O (space group Pna21, a = 31.9525(17) Å, b = 14.7203(8) Å, c = 11.8592(6) Å, V = 5578.0(5) Å3, Z = 4). The metal to ligand ratio in these complexes is 1 : 1; the complexes are obtained at 0.025–0.1 mol/l concentrations of the metals in solutions. With higher lanthanide concentrations (0.7–1 mol/l), the 2 : 1 complex with cucurbit[6]uril is formed of the composition [{ Gd(NO3)(H2O)5}2(C36H36N24O12)](NO3)4 ⋅ 6.5H2O (space group \(P\bar 1\), a = 13.3972(6) Å, b = 14.4994(5) Å, c = 18.3290(8) Å, α = 73.5610(10)°, β = 87.2590(10)°, γ = 87.5540(10)°, V = 3409.4(2) Å3, Z = 2) and isotypical complex [{Gd(NO3)(H2O)5}2{(C5H5N) ⊂ (C36H36N24O12)}](NO3)4 ⋅ 8H2O with a pyridine molecule inside the cucurbit[6]uril cavity (space group P21/n, a = 14.8263(6) Å, b = 13.3688(7) Å, c = 18.5970(9) Å, β = 107.5860(10)°, V = 3513.8(3) Å3, Z = 2). According to X-ray diffraction data, the metal atoms of the title complexes coordinate the O atoms in portals of cucurbit[6]uril molecules.