Mixed Transition Metal/Lanthanide Complexes: Structural Characterization of Solids Containing Cage Amine Chromium(III) Cations and Tris(dipicolinato)lanthanide Anions

Abstract

As the foundation to a survey of interactions between chromium(III) and lanthanide(III) ions within the same crystal lattice, a series of complexes of stoichiometry [Cr((NH₂)₂sar)]- [ Ln ( dipic )₃].8H₂O (sar = 3,6,10,13,16,19-hexaazabicyclo[6.6.6] icosane, Ln = La-Lu plus Y, dipic = pyridine-2,6-dicarboxylate) has been synthesized and structurally characterized by room-temperature single-crystal X-ray studies. An isomorphous series is found for all Ln, being triclinic, Pī , a ≈ 18.1, b ≈ 13.3, c ≈ 11 Ǻ, α ≈ 111.5, β ≈ 96.2, γ ≈ 109.2°, Z = 2 formula units, full structure determinations being recorded for Ln = La (conventional R 0.048 on |F| for N_o 6494 independent 'observed' [I > 3σ(I)] reflections at convergence), Ce (R 0.036 for N_o 8980) and Lu (R 0.046 for N_o 6791). A less well defined protonated series, with a 2:3 Cr/ Ln ratio, has also been characterized specifically for Ln = La [orthorhombic, Pbca , a 26.223(8), b 53.17(3), c 18.329(9) Ǻ, Z = 8; R 0.092 for N_o 5104], the lutetium analogue having a similar cell.