Abstract. The reaction of Ln(NO 3 ) 3 (Ln ϭ Ce, Tb, or Yb) with Ph 2 PCH 2 CH 2 P(O)Ph 2 in various molar ratios produces Ln(NO 3 ) 3 (OPPh 2 CH 2 CH 2 PPh 2 ) 3 . X-ray powder diffraction demonstrates that the three compounds are isostructural. Single crystal X-ray diffraction structures were obtained for Ln ϭ Ce and Tb. The compound are isomorphous and crystallize in the trigonal R3c space group. The lanthanide ions are nine-coordinate with three bidentate nitrate ions and three (OPPh 2 CH 2 CH 2 PPh 2 ) ligands coordinated through oxygen. If the coordination sphere i