Antiprismatic Coordination about Xenon: The Structure of Nitrosonium Octafluoroxenate(VI)

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Science  24 Sep 1971:
Vol. 173, Issue 4003, pp. 1238-1239
DOI: 10.1126/science.173.4003.1238


The structure of nitrosonium octafluoroxenate(VI), 2NOF · XeF6, has been determined by means of single-crystal x-ray counter methods (R-index = 0.046, weighted R-index = 0.042). The space group is Pnma, with a = 8.914(10) angstroms, b = 5.945(10) angstroms, and c = 12.83(2) angstroms (the numbers in parentheses are the standard deviations to the least significant digit or digits); the calculated density (ρ) is 3.354 grams per cubic centimeter, and there are four formula units per unit cell. The material consists of well-separated NO+ and (XeF8)2- ions; the structural formula is thus (NO)2 (XeF8). The anion configuration is that of a slightly distorted Archimedean antiprism. The observed distortion appears incompatible with a lone-pair repulsion model. Xenon-fluorine bond lengths of 1.971(7), 1.946(5), 1.958(7), 2.052(5), and 2.099(5) angstroms were found.