N,N,N-Tris(diphenylphosphorylmethyl)amine

Abstract

The structure of N,N,N-tris(diphenylphosphorylmethyl)amine, C 39 H 36 NO 3 P 3 , at 103 K has monoclinic (P2 1 /c) symmetry. Two molecules, each with pseudothreefold rotation symmetry, crystallize in the asymmetric unit of the monoclinic unit cell. The compound acts as ligand for the stabilization of metal ions with flexible coordination enabling three-or fourfold coordination. Structure descriptionPhosphine oxides act as ligands for stabilizing oxophilic metal ions via complex formation. Many complexes of phosphine oxides stabilizing lanthanide and actinide ions have been described (some recent examples are: Baulin et al., 2015; Bowden et al., 2015; Dong et al., 2015; Hasegawa et al., 2015; Hirai et al., 2015 Hirai et al., , 2016 Tolpygin et al., 2015; Yanagisawa et al., 2015). Tripodal ligands form a pocket in which the metal can be embedded via spherical coordination and therefore create a shielded pocket contributing to an even greater stabilization of the complexes (see: Cecconi et al., 2000Cecconi et al., , 2001a Fu et al., 2011; Li et al., 2010; Somov & Chausov, 2014, 2015 Somov et al., 2015 Somov et al., , 2016.In the crystal structure of N,N,N-tris(diphenylphosphorylmethyl)amine, the two molecules in the asymmetric unit show a comparable arrangement (r.m.s. deviation = 0.5340 Å ), even if there are no hydrogen-bond bridges or other external influences (Figs. 1 and 2). Both molecules exhibit a polar pocket with a tripodal arrangement of the N(CH 2 PR 2 O) 3 group; the P and O atoms of this group show a nearly planar arrangement (mean deviation for the selected atoms from this plane for molecule 1 = 0.065 Å and for molecule 2 = 0.074 Å ). The molecules are oriented such that the O atoms point always in the direction of a P atom of a neighbouring arm, establishing an average intramolecular P-O distance of 4.46 (5) Å . The reason of this arrangement is probably found in a dipole-dipole interaction between the partially negative O atom and the partial positive P atom. This arrangement leads, for both molecules, to the formation of a hydrophobic