| Abstract
| - The new nonadentate tripodal ligand trenphen {tris[(1,10-phenanthroline-2-carboxamido)-ethyl]amine} has beensynthesized by condensation of tren [tris(2-aminoethyl)amine] with an excess of 1,10-phenanthroline-2-carboxylicacyl chloride. The ligand trenphen and its lanthanide complexes (Sm, Nd, Eu, Tb, and Lu) have been structurallycharacterized by single-crystal X-ray diffractometry. Crystals of trenphen·H2O·CH3CN, 1, are monoclinic, spacegroup P2(1)/n, a = 14.9923(8) Å, b = 17.4451(10) Å, c = 17.1880(10) Å, β = 114.8290(10)°, V = 4079.9(4)Å3, Z = 4. The solid-state crystal structures of the isostructural [Ln(trenphen)](OTf)3·yH2O·xEt2O·zCH3CN(OTf = CF3SO3) (Ln = Nd, y = 0.5, x = 1, z = 3 (2); Ln = Sm, y = 0.5, x = 1, z = 3 (3); Ln = Eu, y = 0.5,z = 3 (4); Ln = Tb, y = 0.5, x = 1, z = 1.5 (5); Ln = Lu, y = 0.5, x = 1, z = 1.5 (6)) (trigonal, P-3, Z = 2)show that the covalent tripod trenphen undergoes a rearrangement in the presence of lanthanide ions yieldingthree tridentate binding units which encapsulate the nine-coordinated lanthanide ion with a slightly distorted,tricapped, trigonal prismatic coordination geometry. The correlation observed between the decrease of Ln−Ndistances and the metal ionic radius indicates that trenphen, although containing rigid bidentate phenanthrolineunits, is sufficiently flexible to self-organize without steric constraints around lanthanide ions of different size.Solution-state NMR studies show that complexes 2−6 exist in acetonitrile solution as discrete rigid C3-symmetricspecies retaining the triple-helical structure observed in the solid state. NMR and ES-MS titration show the formationof bimetallic and trimetallic species in the presence of an excess of metal, whereas mononuclear bistrenphencomplexes are obtained in the presence of an excess of ligand.
- A new covalent tripodal ligand, containing phenanthroline units connected to a tris(2-aminoethyl)amine anchor through amide linkage, and its lanthanide(III) complexes (Nd, Sm, Eu, Tb, and Lu) have been prepared and their crystal structures and solution structure have been determined. The X-ray crystal structure shows that the Ln(III) complexes are well-encapsulated by the tripode acting as a nonadentate ligand with six phenanthroline nitrogens and three trisamide oxygens.
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