Octaethyl-triphosphadiazenium dimethyltrifluorosificate, [Et3PNPEt2NPEt3](+)[SiF3Me2](-)

Xenondifluoride reacts with equimolar amounts of the silylated phosphoraneimine Me3SiNPEt3 in acetonitril solution at -30degreesC to give [Et3PNPEt2NPEt3](+)[SiF3Me2](-) (1), which was characterized by IR spectroscopy and by single crystal X-ray crystallography. Space group P2(1)/n, Z = 4, lattice dimensions at 220 K: a = 1129.21(8), b = 1729.06(11), c = 1426.05(10) pm, beta = 99.628(8)degrees, R-1 = 0.0450. The cation of 1 contains an S-shaped PNPNP skeleton with PN distances of 158.0 pm on average. The [SiF3Me2](-) anion of 1 is isostructural with the well-known PF3Me2 molecule with the methyl groups and one fluorine ligand in equatorial positions of the trigonal bipyramidal coordinated silicon atom (local symmetry C-2v).