Syntheses, crystal structures, and some properties of heavier lanthanide(III) complexes with optically active N,N '-bis(2-hydroxybenzyl)-N,N '-bis(2-pyridylmethyl)-R-1,2-propanediamine

The reaction of N,N '-bis(2-hydroxybenzyl)-N,N '-bis(2-pyridylmethyl)-R-1,2-propanediamine (R-bbppnH(2)) with Ln(NO3)(3) center dot nH(2)O (Ln = Tb, Dy, Ho, Er, Tm, Yb, or Lu) stereoselectively gave an optically active complex, [Ln(R-bbppn)(NO3)]. All the complexes crystallize in the same acentric orthorhombic space group of C222(1). The central Ln(III) in the complex is coordinated by four oxygens from two phenolates of R-bbppn and one bidentate nitrate and by four nitrogens from two pyridines and one bidentate propanediamine of R-bbppn to form a distorted dodecahedral geometry. The combinations of four oxygens and four nitrogens afford two separate trapeziums, which are almost orthogonal to each other. Although two optical isomers, Delta Lambda Delta and Lambda Delta Lambda, are possible for such a structure, the absolute configuration of the complex is stereoselectively unified to Delta Lambda Delta. Furthermore, two chiral nitrogens in the complex are fixed to R configurations, and the five-membered propanediamine and pyridylmethylamine chelate rings take lambda and delta configurations, respectively. These stereoselectivities reflect an introduction of the optically active R-propanediamine moiety in the ligand. The electronic absorption, CD, and diffuse reflectance spectra, magnetic susceptibilities, and molar conductivities of the complexes are also discussed in conjunction with their structures.