Symmetry and structure of XeO2F2 by neutron diffraction

Abstract

The molecular symmetry and crystal structure of XeO2F2 have been determined from single crystal neutron diffraction data. The structure is orthorhombic (Cmcm) with a =6.443(3), b =6.288(3), c =8.312(3) Å, Z =4, and Dc =4.10 g cm−3. The neutron Patterson established the structure model which refined to wR (F)=0.069. The structure consists of molecular XeO2F2 units of C2ν symmetry bond together by weak Xe–O bridges. The configuration of XeO2F2 is that of a trigonal bipyramid with axial fluorine and equatorial oxygen atoms and one vacant equatorial position. the Xe–O and Xe–F distances are 1.714 and 1.899 Å and the O–Xe–O, O–Xe–F, and F–Xe–F angles are 105.7°, 91.6°, and 174.7°, respectively.

Synthesis, vibrational and NMR spectroscopic characterization of [N(CH3)4][IO2F2] and X-ray crystal structure of [N(CH3)4]2[IO2F2][HF2]

“…The axial F-I-F angle is slightly bent (176.73(8)8) towards the lone-pair position, away from the two I-O double bond domains, and contrasts with the essentially linear F-I-F arrangement (179.1(5)8) in the K + salt [8]. The bending of the axial ligands in the pseudotrigonal bipyramidal AX 2 Y 2 E structures towards the lonepair position has also been found in the crystal structures of XeO 2 F 2 (174.7(4)8) [19], XeO 2 F 2 ÁTcO 2 F 3 (175.7(6)8) [20], and XeO 2 (OTeF 5 ) 2 (163.7(2)8) [21], and, in the case of XeO 2 F 2 , has been attributed to a non-spherical charge distribution of the lone pair, which is more extended in the equatorial plane and seems to reduce the repulsive } (2) 99(3) Lattice modes 84 (2) a Abbreviations denote shoulder (sh), very strong (vs), strong (s), medium (m), weak (w), very weak (vw), and broad (br). b The NðCH 3 Þ þ 4 cation modes were observed in the Raman spectrum (À100 8C) at 376 (1), 384(1), n 8 (E); 456 (2), n 19 (T 2 ); 756 (7), n 3 (A 1 ); 942 sh, 947 (10), 950 sh, n 18 (T 2 ); 1174(1), 1179(2), n 7 (E); 1292(1), n 17 (T 2 ); 1398(2), 1405(2), 1409(1), n 16 (T 2 ); 1457 (1), 1469(16), 1474(14), n 2 (A 1 ), n 6 (E); 2788(2), 2804(1), 2807 (1), 2899(1) 2907(1), 2960(8), 2975 sh, 2990(2), 3001(2), 3032(6), 3037(5), 3043 (8), 3059(7) cm À1 , n(CH 3 ) and binary bands [15,16].…”

“…The F Á Á Á F distance in trans-Ru(dmpe) 2 (H)(F Á Á Á HF) of 2.286(8) Å is close to that of ionic bifluoride, however, 1 H and 19 F NMR spectroscopic results favor a hydrogen-bonded description [27]. The number of structurally characterized compounds containing bridging hydrogen fluoride molecules is limited to the dimeric niobium and osmium species, [(h 5 -C 5 Me 5 )NbF 4 (HF)AsF 3 ] 2 [28] (14) 3020 (19) 2968 (16) n(CH 3 ) and binary bands 2933(13) 2897 (7) 2837 (11) a The Raman spectrum was recorded on a single crystal inside a glass Lindemann capillary at room temperature using 514.5 nm excitation. Values in parentheses denote relative Raman intensities; and sh a shoulder.…”

“…[20], and XeO 2 (OTeF 5 ) 2 (106.5(2)8) [21]. The increased bond polarity in an anionic species is also reflected in the longer I-O and I-F bond lengths in the IO 2 F À 2 anion when compared with the Xe-O (1.714(4) Å ) and Xe-F (1.899(3) Å ) bond lengths of XeO 2 F 2 [19].…”

“…Hence, the FHF moieties in the aforementioned transition-metal complexes are best described as HF molecules hydrogen-bonded to fluorine ligands, which is supported by 19 F and 1 H NMR spectroscopic studies of these complexes [23][24][25][26]. The F Á Á Á F distance in trans-Ru(dmpe) 2 (H)(F Á Á Á HF) of 2.286(8) Å is close to that of ionic bifluoride, however, 1 H and 19 F NMR spectroscopic results favor a hydrogen-bonded description [27].…”

Noble‐Gas Compounds

“…Both oxygen atoms and the electron lone pair are in the equatorial plane, whereas the fluorine atoms are in the axial positions, resulting in a distorted tetrahedral geometry. The Xe-F distance is 171.4(4) pm, while the Xe-O distance is 189.9(3) pm (78). It is a colorless solid (Table 1).…”