Structure analyses combining electron diffraction and microwave data

Abstract

Molecular parameters for XeOF, derived from electron diffraction data are compared with those previously reported in vibrational and rotational spectroscopic studies of the molecule. Additional least-squares calculations were performed which simultaneously fitted the diffraction and microwave data. Although results for the separate experiments are in good agreement, each set of parameters suffers from fairly large uncertainties which are largely unrelated to the accuracy of the respective physical measurements. A comparison of parameter correlations for the separate and joint least-squares calculations indicates that the troublesome correlations in the individual sets of data are significantly reduced when the two sets of data are combined. Various interpretational difllculties associated with the process of combining the data from the two experiments are discussed and suggestions are made for estimating uncertainties in cases where the observational residuals are far from random.

Syntheses and X-ray Crystal Structures of α- and β-[XeO2F][SbF6], [XeO2F][AsF6], [FO2XeFXeO2F][AsF6], and [XeF5][SbF6]·XeOF4and Computational Studies of the XeO2F+and FO2XeFXeO2F+Cations and Related Species

“…The structure of XeOF 4 is a square-based pyramid of approximate C 4 v symmetry corresponding to an AX 4 YE VSEPR arrangement of bond-pair and lone-pair domains. The geometric parameters obtained for XeOF 4 in the present crystal structure (Table ) are in good agreement with the values obtained from previous microwave and electron diffraction structural studies. , In the current and earlier studies, the O−Xe−F bond angles are also found to be slightly greater than 90°, within ±3σ, implying that the repulsive effect of the doubly bonded oxygen atom is comparable to that of the free valence electron lone pair.

4 X-ray crystal structure of [XeF 5 ][SbF 6 ]·XeOF 4 .

…”

“…The net positive charge of the XeO 2 F + cation leads to a shorter and less polar Xe−F bond. The Xe−O bond lengths in the XeO 2 F + cation are similar to those observed for other xenon(VI) oxide fluorides [XeOF 4 , 1.703(15), 1.7053(9)−1.711(11), and 1.713(3) Å; XeOF 3 + , 1.692(13) Å; XeO 2 F 2 , 1.714(4) 17 and 1.731(9) Å; XeO 3 , 1.76(2) Å]. Although it is not possible to differentiate between the Xe−O bond lengths obtained for XeO 2 F 2 and the XeO 2 F + cation by diffraction methods, the higher symmetric and antisymmetric XeO 2 stretching frequencies suggest that if they are essentially pure vibrational modes, the Xe−O bonds of XeO 2 F + (867 and 923 cm -1 ; 873 and 931 cm -1 8 ) are shorter and less polar than those of XeO 2 F 2 (845−850 and 882−905 cm -1 ) .…”

“…The Xe−F bond of XeO 2 F + is shorter, within ±3σ, than that in XeOF 4 [1.900(5) Å; 1.901(3)−1.9040(0) Å; 1.895(2) and 1.890(2) Å] and XeO 2 F 2 [1.899(3) Å; 1.892(13) and 1.925(13) Å] and intermediate with respect to Xe−F ax [1.879(12) Å] and Xe−F eq [1.821(12) Å] in XeOF 3 + …”

Fluoride Ion Donor Properties of TcO2F3and ReO2F3: X-ray Crystal Structures of MO2F3·SbF5(M = Tc, Re) and TcO2F3·XeO2F2and Raman and NMR Spectroscopic Characterization of MO2F3·PnF5(Pn = As, Sb), [ReO2F2(CH3CN)2][SbF6], and [Re2O4F5][Sb2F11]

“…There are two types of axial Xe−F bonds in the present structure. One is slightly longer (1.925(13) Å) than the other (1.892(13) Å) as a result of a secondary fluorine bridge contact with Xe in a neighboring XeO 2 F 2 molecule, and both agree well with the Xe VI −F bond lengths previously reported for XeO 2 F 2 (1.899(3) Å) 42 and XeOF 4 (1.903(5), 1.9024(9), 1.892(2) 45 Å). All bond angles are identical to those in XeO 2 F 2 .…”

“…An interesting feature of this structure is that the XeO 2 F 2 molecules have secondary contacts to Xe through fluorine bridging within the XeO 2 F 2 chains (Figure b), rather than through Xe···O contacts as in the structure of XeO 2 F 2 . The Xe−O distance (1.734(9) Å) is equal (within 3σ) to that in XeO 2 F 2 (1.714(4) Å) and similar to the XeO bond lengths of XeOF 4 (1.706(15), 1.708(2), 1.711(3) Å) and XeO 3 (1.76(3) Å) . There are two types of axial Xe−F bonds in the present structure.…”