C. Piguet, J. Bünzli, G. Bernardinelli
Jul 17, 1996
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0
Influential Citations
180
Citations
Quality indicators
Journal
Journal of the American Chemical Society
Abstract
The segmental ligand 2-{6-[N,N-diethylcarbamoyl]pyridin-2-yl}-1,1‘-dimethyl-5,5‘-methylene-2‘-(5-methylpyridin-2-yl)bis[1H-benzimidazole] (L2) reacts with stoichiometric amounts of Ln(III) (Ln = La−Nd, Sm−Tb, Tm−Lu, Y) and Zn(II) in acetonitrile to yield quantitatively and selectively the heterodinuclear triple-helical complexes [LnZn(L2)3]5+ under thermodynamic control. The crystal structure of [EuZn(L2)3](ClO4)(CF3SO3)4(CH3CN)4 (13; EuZnC111H111N25O19F12S4Cl, monoclinic, C2/c, Z = 8) shows the wrapping of the three ligands L2 about a pseudo-C3 axis passing through the metal ions. Zn(II) occupies the distorted pseudooctahedral capping coordination site defined by the three bidentate binding units while Eu(III) lies in the resulting “facial” pseudotricapped trigonal prismatic site produced by the three remaining tridentate units as exemplified by luminescence measurements using the Eu(III) structural probe. The separation of contact and pseudocontact contributions to the 1H-NMR paramagnetic shifts of the ...