CRYSTAL AND MOLECULAR-STRUCTURE OF THE MONOBINO DICYCLOPHOSPHAZENE N3P3CL5 [HN-(CH2)3-O-(CH2)6-O-(CH2)3-NH] CL5P3N3

Reaction of N3P3Cl6 with 4,11-dioxatetradecane-1,14-diamine (coded as 3O6O3) in THF leads stereospecifically to the mono-BINO (3O6O3) derivative in which one [HN-(CH2)3-O-(CH2)6-O-(CH2)3-NH] ligand bridges two N3P3Cl5 moieties. This compound crystallizes in the monoclinic system, P2(1)/c, a = 11.788 (2), b = 16.660 (6), c = 9.241 (3) angstrom, beta = 110.81 (2)-degrees, V = 1696 (2) angstrom 3, rho-x = 1.66 (2) Mg m-3, R = 0.059 for 1823 unique reflections and 179 variable parameters. The [HN-(CH2)3-O-(CH2)6-O-(CH2)3-NH] ligand appears quite unfolded with twelve atoms strictly coplanar. The two N3P3Cl5 moieties are trans to this plane with a double scorpion sting-like conformation at the edgings of the bridge. (C-C) bond lengths and (C-C-C) bond angles in the ligand are 1.514 (1) angstrom and 111.2 (8)-degrees, respectively, which is very close to refined parameters recently proposed by Allinger et al. (1.5247 angstrom, 111.0-degrees) in their molecular mechanics force field MM3. Thus, the van't Hoff model (1.54 angstrom, 109.5-degrees) which is correct for pure T(d) structures of methane and neopentane, is no longer suitable for the description of C2v carbon atoms in aliphatic chains.