Abstract:The crystal structure of XeF3+SbF6' has been accurately determined from three-dimensional X-ray counter data. Crystals are monoclinic with a = 5.394 (1) A, b = 15.559 (2) A, c = 8.782 (1) A, ß = 103.10 (1)°, V= 717.84 A3, Z = 4, and dc = 3.92 g cm-3. The structure has been refined in space group P2jn to a final conventional R factor of 0.048 for 1264 independent reflections with / > 3 ( ). The structure consists of XeF3+SbF6' units with a close contact of 2.485 (10) A between the Xe atom of the T-shaped cation… Show more
“…Principal bond lengths and angles about iodine are as (2) in the 1-0 bonds is much less pronounced and is probably a consequence of the crystal packing (vide infra). This T-shaped geometry is predicted from VSEPR (2 1) theory and has been observed for a number of tellurium(I1) (22), chlorine(II1) (23), iodine(II1) (1 -5, 24), and xenon(1V) (25) complexes. The trifluoroacetate groups are oriented such that they are almost perpendicular to each other with a dihedral angle between the least-squares mean planes defined by the C-C02 atoms of 84.3(4)" and 82.5(4)" for molecules 1 and 2 respectively.…”
This paper is dedicated to Professor Ronald J . Gillespie on the occasion of his 65th birthday MADHUMITA BARDAN, THOMAS BIRCHALL, CHRISTOPHER S. FRAMPTON, and PRATIBHA KAFQOR. Can. J. Chem. 67, 1878 (1989).The lZ71 Mossbauer spectra of a series of mono-and diaryliodine(II1) carboxylates have been recorded at 4.2 K. The observed parameters are shown to be strongly dependent on the primary bonding arrangement about iodine only and the secondary bonding
“…Principal bond lengths and angles about iodine are as (2) in the 1-0 bonds is much less pronounced and is probably a consequence of the crystal packing (vide infra). This T-shaped geometry is predicted from VSEPR (2 1) theory and has been observed for a number of tellurium(I1) (22), chlorine(II1) (23), iodine(II1) (1 -5, 24), and xenon(1V) (25) complexes. The trifluoroacetate groups are oriented such that they are almost perpendicular to each other with a dihedral angle between the least-squares mean planes defined by the C-C02 atoms of 84.3(4)" and 82.5(4)" for molecules 1 and 2 respectively.…”
This paper is dedicated to Professor Ronald J . Gillespie on the occasion of his 65th birthday MADHUMITA BARDAN, THOMAS BIRCHALL, CHRISTOPHER S. FRAMPTON, and PRATIBHA KAFQOR. Can. J. Chem. 67, 1878 (1989).The lZ71 Mossbauer spectra of a series of mono-and diaryliodine(II1) carboxylates have been recorded at 4.2 K. The observed parameters are shown to be strongly dependent on the primary bonding arrangement about iodine only and the secondary bonding
“…This suggests that BiF 5 is weaker as a Lewis acid than SbF 5 . Similarly, the Xe–F bond length of the bridging fluoride in [XeF 3 ][SbF 6 ] is 2.49 Å, whereas the analogous bond length in [XeF 3 ][BiF 6 ] is 2.25 Å, indicating that the latter is perhaps better described as XeF 4 ·BiF 5 . Finally, the conductivities of fluorosulfuric acid (HSO 3 F) solutions of the group 15 pentafluorides follow the order SbF 5 > BiF 5 > AsF 5 > PF 5 …”
The global electrophilicity index
(GEI) has been further explored as a general and base-free metric
for Lewis acidity. A number of computational methods, including post-Hartree–Fock,
density functional theory, and time-dependent density functional theory,
have been explored. In this fashion, we sought the method most applicable
to a range of different Lewis acids with differing structural and
electronic features, including boron trihalides, silicon tetrahalides,
fluoroaryl boranes, and group 15 pentahalides. The most accurate and
computationally efficient approach was found to use the energies of
the orbitals from a geometry optimization at the B3LYP/def2-TZVP level
of theory. In addition, the GEI is shown to act as an effective acidity
metric that is complementary to the fluoride ion affinity. The GEI
also proved to be a better gauge of Lewis acidity for softer bases,
as confirmed by comparison to the iodide ion affinity of the group
15 pentahalides.
“…Assignments of the cation modes were made by comparison with the known transition metal cis -dioxo species, cis -OsO 2 F 4 , cis -ReO 2 F 4 - , and the cis -TcO 2 F 4 unit of polymeric TcO 2 F 3 , as well as with cis -IO 2 F 4 - , and were confirmed by local (LDFT) and nonlocal (NLDFT) density functional theory calculations (see Table and Computational Results ). Assignments of anion modes are based on published data for the Sb 2 F 11 - − and AsF 6 - 49,52,54 anions. 3 Raman spectra of (a) microcrystalline F( cis -OsO 2 F 3 ) 2 + AsF 6 - recorded under a layer of liquid HF/AsF 5 at −70 °C in an FEP sample tube, (b) microcrystalline F( cis -OsO 2 F 3 ) 2 + Sb 2 F 11 - recorded at −110 °C in a 3-mm-o.d.…”
Osmium dioxide tetrafluoride, cis-OsO(2)F(4), reacts with the strong fluoride ion acceptors AsF(5) and SbF(5) in anhydrous HF and SbF(5) solutions to form orange salts. Raman spectra are consistent with the formation of the fluorine-bridged diosmium cation F(cis-OsO(2)F(3))(2)(+), as the AsF(6)(-) and Sb(2)F(11)(-) salts, respectively. The (19)F NMR spectra of the salts in HF solution are exchange-averaged singlets occurring at higher frequency than those of the fluorine environments of cis-OsO(2)F(4). The F(cis-OsO(2)F(3))(2)(+)Sb(2)F(11)(-) salt crystallizes in the orthorhombic space group Imma. At -107 degrees C, a = 12.838(3) Å, b = 10.667(2) Å, c = 11.323(2) Å, V = 1550.7(8) Å(3), and Z = 4. Refinement converged with R = 0.0469 [R(w) = 0.0500]. The crystal structure consists of discrete fluorine-bridged F(cis-OsO(2)F(3))(2)(+) and Sb(2)F(11)(-) ions in which the fluorine bridge of the F(cis-OsO(2)F(3))(2)(+) cation is trans to an oxygen atom (Os-O 1.676 Å) of each OsO(2)F(3) group. The angle at the bridge is 155.2(8) degrees with a bridging Os---F(b) distance of 2.086(3) Å. Two terminal fluorine atoms (Os-F 1.821 Å) are cis to the two oxygen atoms (Os-O 1.750 Å), and two terminal fluorine atoms of the OsO(2)F(3) group are trans to one another (1.813 Å). The OsO(2)F(3)(+) cation was characterized by (19)F NMR and by Raman spectroscopy in neat SbF(5) solution but was not isolable in the solid state. The NMR and Raman spectroscopic findings are consistent with a trigonal bipyramidal cation in which the oxygen atoms and a fluorine atom occupy the equatorial plane and two fluorine atoms are in axial positions. Density functional theory calculations show that the crystallographic structure of F(cis-OsO(2)F(3))(2)(+) is the energy-minimized structure and the energy-minimized structures of the OsO(2)F(3)(+) cation and ReO(2)F(3) are trigonal bipyramidal having C(2)(v)() point symmetry. Attempts to prepare the OsOF(5)(+) cation by oxidative fluorination of cis-OsO(2)F(4) with KrF(+)AsF(6)(-) in anhydrous HF proved unsuccessful.
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