Preparation, properties and structure of di-(acetamidinium)-difluoropentathiodiphosphate

Abstract

Plate-shaped, colorless crystals were grown from a solution, originating with the reaction of P 4S 10 and NH 4F in CH 3CN. By a molar ratio of 4NH 4F/P 4S 10, third of P 4S 10 reacted to Di-(acetamidinium)-difluoropentathiodiphosphate, [CH 3C(NH 2) 2] 2P 2S 5F 2. Crystals are melting in the range of 134 – 142 °C under their decomposition. The crystal structure has been determined from three-dimensional MoK β data, collected on a CAD-4 diffractometer. It crystallizes in the space group C2/c with four formula units in a cell of dimensions a = 10.600(5) b = 10.069(5) c = 15.129(8) Ā β = 92,35(5)° with V = 1613.4 Ā 3, D o = 1,557 g.cm −3, D o 1.49 g.cm −3. The structure was solved by the direct methods program system MULTAN 82 and anisotropically refined by least-squares techniques to a final R = 0,037 based on 966 independent intensities. The hydrogen atoms were located from a difference map. The difluoropentathiodiphosphate-anion consists of two PS 3F-tetrahedra which are connected together by a common sulfur atom. This bridge-atom occupies a special equivalent position on a twofold rotation axis, therefore the anion shows the point symmetry 2. Bond distances and angles within the tetrahedra have the usual values (P-S bridge = 2,075(1) Ā, P-S terminal = 1.951(1) and 1.944(1) Ā, P-F = 1.577(2) Ā), < P-S-P = 107.8(1)°. The nitrogen- carbon-atoms of the acetamidinium-cation are lying in plane. Bonds lengths are: CC = 1.485(5) Ā, CN = 1.301(4) and 1.280(5) Ā. There are hydrogen bonds in the structure.