Zur Kristallchemie ungeladener Phosphazen-Basen, I [1] Strukturen zweier Hydrate und eines Acetats von Tris(dimethylamino)methyliminophosphoran / Crystal Chemistry of Uncharged Phosphazene Bases, I [1] Structures of Two Hydrates and an Acetate of Tris(dimethylamino) methyliminophosphorane

Frank Hartmann, Dietrich Mootz, Reinhard Schwesinger
1996 Zeitschrift für Naturforschung. B, A journal of chemical sciences  
Two hydrates and an acetate of the uncharged, very strong phosphazene base tris(dimethylamino)methyliminophosphorane, (Me2N)3P=NMe (for short Me-P1), have been characterized by their crystal structures. A monohydrate, Me-P1 · H2O , mp. 3°C, is monoclinic with space group P21/n and Z = 4 formula units per unit cell of dimensions a = 8.585, b = 11.107, c = 13.083 Å, and β = 97.76° at -30°C. Another hydrate, Me-P1 · 1.75 H2O, mp. - 11°C. is triclinic with P1̅, Z = 4, a = 7.924, b = 11.768, c =
more » ... 57 Å, α = 89.70°,β = 86.30°, and 7 = 86.54° at -100°C. An acetate, Me-P1 · CH3COOH, mp. 88°C, is also triclinic with P1̅, Z = 2, a = 7.558, b = 8.193, c = 11.431 A, a = 93.60°, β = 96.52°, and γ = 92.12° at-100°C. In the hydrate Me-P1 · H2O , a centrosymmetric dimer of the formula unit is formed by O-H···N hydrogen bonds arranged in a four-membered ring. In the hydrate Me-P1 · 1.75 H2O , two rings of this kind are linked by additional water molecules into an infinite chain each. Both hydrate structures are those of molecular adducts, in spite of the great strength of the base. By contrast, the structure of the acetate Me-P1 · CH3COOH is clearly ionic, with an ion pair being formed by a bifurcated (three-center) hydrogen bond N-H(···O)2 from the protonated N atom of the base cation to both O atoms of one and the same acid anion.
doi:10.1515/znb-1996-1001 fatcat:kyh5asoacncavhjupl24wgmffq