Crystal Structure of N,N,N′,N′-Tetrakis(methyldiphenylphosphino)-bis-(2′-phenoxy)-3,6-dioxaoctane

Abstract

Forty years ago, application of the Mannich reaction to the synthesis of aminomethylphosphines developed a new research area for the synthesis of novel phosphine ligands. 1,2 The syntheses of some macrocyclic multidentate crown-ethers and podands containing P-C-N linkages have been reported. 3,4 The title ligand was prepared from a mixture of triethylene glycol bis(2-aminophenyl ether) 5 (2.66 g, 8.00 mmol), diphenylphosphine (5.54 mL, 32.0 mmol) and formaldehyde (7.00 mL, 37% solution in water) in benzene (150 mL) at 55˚C, with argon being passed over for 6 h. After the evaporation of benzene, the residue was crystallized from dichloromethane, yield 5.85 g (65%), m.p. 125˚C.The structure was solved by direct methods. Since the difference synthesis did not clarify the positions of the H atoms, they were positioned geometrically with C-H distances of 0.97 and 0.93 Å for CH2 and CH, respectively, and a riding model was used during the refinement.The results of X-ray structure determination are given in Tables 1 -3. The title molecule, which is a polydentate podand (Fig. 2), consists of four etheral oxygens, two tertiary amine nitrogens and four diphenylphosphin groups. It forms stable complexes with some lanthanides and transition-metal cations. The asymmetric unit contains only one half molecule.The sums of the bond angles, around N1, P1 and P2 atoms [348.2(5), 301.6(3) and 304.2(3)˚, respectively] are the indications of pyramidality. The φCC (O1-C20-C21-O2), φCO (C20-C21-O2-C22) and φOC (C21-O2-C22-C22) torsion angles are -67.9(7), -176.5(5) and 179.9(7)˚, respectively, showing that the conformations about C20-C21 is gauche and those around C21-O2 and O2-C22 are anti.The O1-C19 [1.369 (7) The title molecule, [C70H68N2O4P4], is a polydentate podand consisting of four etheral oxygens, two tertiary amine nitrogens and four diphenylphosphin groups. It crystallizes in the triclinic space group P1, and there is only one half a molecule in the asymmetric unit. The coordinations around the N and P atoms are pyramidal. The conformations about C20-C21, O2-C21 and O2-C22 are gauche, anti and anti, respectively.