Difference between revisions of "Dibromine monoxide"
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{{chembox | {{chembox | ||
| − | | IUPACName = Oxygen dibromide | + | | IUPACName = Oxygen dibromide{{#tag:ref|Although oxygen is more [[Electronegativity|electronegative]] than bromine on the normal numerical scales,<ref>{{Allred (1961)}}.</ref> it appears after the [[halogen]]s on the conventional electronegativity series used in inorganic nomenclature.<ref>{{RedBook2005|page=260}}.</ref> Hence, OBr<sub>2</sub> is considered a bromide of oxygen, and not an oxide of bromine, for nomenclature purposes.|group=note}} |
| − | | OtherNames = Hypobromous anhydride | + | | OtherNames = Bromine(I) oxide<br/>Hypobromous anhydride<br/>Dibromooxidane<br/>Dibromidooxygen |
| Section1 = {{Chembox Identifiers | | Section1 = {{Chembox Identifiers | ||
| ChemSpiderID = 10686917 | | ChemSpiderID = 10686917 | ||
| Line 11: | Line 11: | ||
}} | }} | ||
| Section2 = {{Chembox Properties | | Section2 = {{Chembox Properties | ||
| − | | Reference = <ref name="G&E">{{Greenwood&Earnshaw1st|pages=996–97}}.</ref> | + | | Reference = <ref name="G&E">{{Greenwood&Earnshaw1st|pages=996–97}}.</ref><ref name="Xstal">{{citation | first1 = In-Chur | last1 = Hwang | first2 = Raimund | last2 = Kuschel | first3 = Konrad | last3 = Seppelt | title = Structures of Bromine Oxygen Compounds | journal = Z. Anorg. Allg. Chem. | volume = 623 | issue = 1–6 | pages = 379–83 | doi = 10.1002/zaac.19976230160}}.</ref> |
| Formula = Br<sub>2</sub>O | | Formula = Br<sub>2</sub>O | ||
| MolarMass = 175.81 g mol<sup>−1</sup> | | MolarMass = 175.81 g mol<sup>−1</sup> | ||
| MeltingPt = −17.5 °C (255.7 K) ''decomp.'' | | MeltingPt = −17.5 °C (255.7 K) ''decomp.'' | ||
| − | | Density = | + | | Density = 4.10 g cm<sup>−3</sup> (crystal) |
| Appearance = dark brown solid | | Appearance = dark brown solid | ||
| + | }} | ||
| + | | Section3 = {{Chembox Structure | ||
| + | | Reference = <ref name="Xstal"/> | ||
| + | | SpaceGroup = P''c''2<sub>1</sub>''n'' (No. 33) | ||
| + | | LattConst_a = 390.4(1) pm | ||
| + | | LattConst_b = 686.2(1) pm | ||
| + | | LattConst_c = 1062.2(2) pm | ||
| + | }} | ||
| + | | Section4 = {{Chembox Thermochemistry | ||
| + | | Reference = <ref>{{citation | title = Photoionization Efficiency Spectrum, Ionization Energy, and Heat of Formation of Br<sub>2</sub>O | first1 = R. Peyton, Jr. | last1 = Thorn | first2 = Paul S. | last2 = Monks | first3 = Louis J. | last3 = Stief | first4 = Szu-Cherng | last4 = Kuo | first5 = Zhengyu | last5 = Zhang | first6 = R. Bruce | last6 = Klemm | journal = J. Phys. Chem. | year = 1996 | volume = 100 | issue = 30 | pages = 12199–203 | doi = 10.1021/jp960405z}}.</ref> | ||
| + | | DeltaHf = +107.1(35) kJ mol<sup>−1</sup> | ||
}} | }} | ||
| Section8 = {{Chembox Related | | Section8 = {{Chembox Related | ||
| Line 22: | Line 33: | ||
| OtherFunctn = [[Bromine dioxide]] | | OtherFunctn = [[Bromine dioxide]] | ||
| Function = [[oxides of bromine]] | | Function = [[oxides of bromine]] | ||
| + | | OtherCpds = [[Hypobromous acid]] | ||
}} | }} | ||
}} | }} | ||
| − | '''Dibromine monoxide''', Br<sub>2</sub>O, is a binary compound of [[bromine]] and [[oxygen]]. It is prepared by the reaction of bromine with [[mercury(II) oxide]] or by the low temperature decomposition of [[bromine dioxide]] in vacuo.<ref name=" | + | '''Dibromine monoxide''', Br<sub>2</sub>O, is a binary compound of [[bromine]] and [[oxygen]]. The dark brown solid is unstable at room temperature.<ref name="G&E"/><ref name="C&W">{{Cotton&Wilkinson5th|page=562}}.</ref> It is prepared by the reaction of bromine with [[mercury(II) oxide]]<ref>{{citation | first1 = E. | last1 = Zintl | first2 = G. | last2 = Rienäcker | title = Über die Existenz eines flüchtigen Bromoxyds | journal = Ber. Dtsch. Chem. Ges. B | year = 1930 | volume = 63 | issue = 5 | pages = 1098–1104 | doi = 10.1002/cber.19300630516}}.</ref><ref>{{citation | first1 = W. | last1 = Brenschede | first2 = H.-J. | last2 = Schumacher | title = Über die Darstellung und einige Eigenschaften eines Bromoxyds von der Formel Br<sub>2</sub>O | journal = Z. Anorg. Allg. Chem. | year = 1936 | volume = 226 | issue = 4 | pages = 370–84 | doi = 10.1002/zaac.19362260409}}.</ref> or by the low temperature decomposition of [[bromine dioxide]] in vacuo.<ref>{{citation | first1 = R. | last1 = Schwarz | first2 = H. | last2 = Wiele | title = Über das Bromoxyd Br<sub>2</sub>O | journal = Naturwissenschaften | year = 1938 | volume = 26 | issue = 45 | page = 742 | doi = 10.1007/BF01774152}}.</ref><ref>{{citation | first1 = Robert | last1 = Schwarz | first2 = Heinz | last2 = Wiele | title = Zur Kenntnis der Bromoxyde (II. Mitteilung) | journal = J. Prakt. Chem. | year = 1938 | volume = 152 | issue = 3–6 | pages = 157–76 | doi = 10.1002/prac.19391520306}}.</ref> Other routes include the [[photolysis]] of mixtures of oxygen and bromine vapour<ref name="Campbell">{{citation | first1 = C. | last1 = Campbell | first2 = J. P. M. | last2 = Jones | first3 = J. J. | last3 = Turner | title = Spectroscopic studies of bromine oxides: the infrared spectrum of solid bromide monoxide | journal = Chem. Commun. (London) | year = 1968 | issue = 15 | pages = 888–89 | doi = 10.1039/C19680000888}}.</ref><ref name="rot">{{citation | first1 = Holger S. P. | last1 = Müller | first2 = Edward A. | last2 = Cohen | title = Dibromine monoxide, Br<sub>2</sub>O: The rotational spectrum and molecular properties | journal = J. Chem. Phys. | volume = 106 | issue = 20 | pages = 8344–54 | year = 1997 | doi = 10.1063/1.473920}}.</ref> and the reaction of BrOTeF<sub>5</sub> with water.<ref name="Xstal"/> |
| + | |||
| + | ==Structure== | ||
| + | Dibromine monoxide has a bent ''C''<sub>2v</sub> structure in the vapour phase, as expected from [[VSEPR theory]], with ''r''(Br–O) = 184.29(20) pm, ''θ''(Br–O–Br) = 112.24(20)°.<ref name="rot"/> In the solid state, the symmetry is lower, with slightly different Br–O distances (185.7(5), 187.5(5) pm) and ''θ''(Br–O–Br) = 114.2(2)°.<ref name="Xstal"/> Solid Br<sub>2</sub>O has also been studied by [[infrared spectroscopy]]<ref name="Campbell"/><ref>{{citation | first1 = D. | last1 = Tevault | first2 = N. | last2 = Walker | first3 = R. | last3 = Smardzewski | first4 = W. | last4 = Fox | title = Infrared spectra of the BrO and OBrO free radicals and of BrOBr and BrBrO molecules in Solid Argon at 10K | journal = J. Phys. Chem. | year = 1978 | volume = 82 | issue = 25 | pages = 2733–36 | doi = 10.1021/j100514a022}}.</ref><ref>{{citation | first1 = S. D. | last1 = Allen | first2 = M. | last2 = Poliakoff | first3 = J. J. | last3 = Turner | title = Photochemistry of an ozone-bromine complex; the IR spectrum of matrix isolated Br<sub>2</sub>O | journal = J. Mol. Struct. | volume = 157 | issue = 1–3 | year = 1987 | pages = 1–15 | doi = 10.1016/0022-2860(87)87078-3}}.</ref><ref name="EXAFS">{{citation | first1 = William | last1 = Levason | first2 = J. Steven | last2 = Ogden | first3 = Mark D. | last3 = Spicer | first4 = Nigel A. | last4 = Young | title = Characterization of dibromine monoxide (Br<sub>2</sub>O) by bromine K-edge EXAFS and IR spectroscopy | journal = J. Am. Chem. Soc. | year = 1990 | volume = 112 | issue = 3 | pages = 1019–22 | doi = 10.1021/ja00159a019}}.</ref> and by [[EXAFS]].<ref name="EXAFS"/> | ||
| + | |||
| + | ==Reactivity== | ||
| + | Dibromine monoxide is a strong [[oxidizing agent]], converting [[iodine]] to [[diiodine pentoxide]] and [[benzene]] to [[1,4-benzoquinone]].<ref name="G&E"/> It is formally the anhydride of [[hypobromous acid]], and gives the [[hypobromite]] ion BrO<sup>−</sup> in alkaline solution.<ref name="G&E"/> | ||
==Notes and references== | ==Notes and references== | ||
Latest revision as of 11:59, 1 January 2011
| Dibromine monoxide | |
|---|---|
| IUPAC name | Oxygen dibromide[note 1] |
| Other names | Bromine(I) oxide Hypobromous anhydride Dibromooxidane Dibromidooxygen |
| Identifiers | |
| InChI | InChI=1/Br2O/c1-3-2 |
| InChIKey | HJCMMOODWZOXML-UHFFFAOYAD |
| Standard InChI | InChI=1S/Br2O/c1-3-2 |
| Standard InChIKey | HJCMMOODWZOXML-UHFFFAOYSA-N |
| CAS number | [] |
| ChemSpider | |
| Properties[3][4] | |
| Chemical formula | Br2O |
| Molar mass | 175.81 g mol−1 |
| Appearance | dark brown solid |
| Density | 4.10 g cm−3 (crystal) |
| Melting point |
−17.5 °C (255.7 K) decomp. |
| Structure[4] | |
| Space group | Pc21n (No. 33) |
| Lattice constant | a = 390.4(1) pm, b = 686.2(1) pm, c = 1062.2(2) pm |
| Thermochemistry[5] | |
| Std enthalpy of formation ΔfH |
+107.1(35) kJ mol−1 |
| Related compounds | |
| Other cations | Difluorine monoxide Dichlorine monoxide |
| Other oxides of bromine | Bromine dioxide |
| Other compounds | Hypobromous acid |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
Dibromine monoxide, Br2O, is a binary compound of bromine and oxygen. The dark brown solid is unstable at room temperature.[3][6] It is prepared by the reaction of bromine with mercury(II) oxide[7][8] or by the low temperature decomposition of bromine dioxide in vacuo.[9][10] Other routes include the photolysis of mixtures of oxygen and bromine vapour[11][12] and the reaction of BrOTeF5 with water.[4]
Structure
Dibromine monoxide has a bent C2v structure in the vapour phase, as expected from VSEPR theory, with r(Br–O) = 184.29(20) pm, θ(Br–O–Br) = 112.24(20)°.[12] In the solid state, the symmetry is lower, with slightly different Br–O distances (185.7(5), 187.5(5) pm) and θ(Br–O–Br) = 114.2(2)°.[4] Solid Br2O has also been studied by infrared spectroscopy[11][13][14][15] and by EXAFS.[15]
Reactivity
Dibromine monoxide is a strong oxidizing agent, converting iodine to diiodine pentoxide and benzene to 1,4-benzoquinone.[3] It is formally the anhydride of hypobromous acid, and gives the hypobromite ion BrO− in alkaline solution.[3]
Notes and references
Notes
- ↑ Although oxygen is more electronegative than bromine on the normal numerical scales,[1] it appears after the halogens on the conventional electronegativity series used in inorganic nomenclature.[2] Hence, OBr2 is considered a bromide of oxygen, and not an oxide of bromine, for nomenclature purposes.
References
- ↑ Allred, A. L. Electronegativity values from thermochemical data. J. Inorg. Nucl. Chem. 1961, 17 (3–4), 215–21. DOI: 10.1016/0022-1902(61)80142-5.
- ↑ Nomenclature of Inorganic Chemistry; IUPAC Recommendations 2005; Royal Society of Chemistry: Cambridge, 2005; p 260. ISBN 0-85404-438-8, <http://www.iupac.org/publications/books/rbook/Red_Book_2005.pdf>.
- ↑ 3.0 3.1 3.2 3.3 Greenwood, Norman N.; Earnshaw, A. Chemistry of the Elements; Pergamon: Oxford, 1984; pp 996–97. ISBN 0-08-022057-6.
- ↑ 4.0 4.1 4.2 4.3 Hwang, In-Chur; Kuschel, Raimund; Seppelt, Konrad Structures of Bromine Oxygen Compounds. Z. Anorg. Allg. Chem., 623 (1–6), 379–83. DOI: 10.1002/zaac.19976230160.
- ↑ Thorn, R. Peyton, Jr.; Monks, Paul S.; Stief, Louis J.; Kuo, Szu-Cherng; Zhang, Zhengyu; Klemm, R. Bruce Photoionization Efficiency Spectrum, Ionization Energy, and Heat of Formation of Br2O. J. Phys. Chem. 1996, 100 (30), 12199–203. DOI: 10.1021/jp960405z.
- ↑ Cotton, F. Albert; Wilkinson, Geoffrey Advanced Inorganic Chemistry, 5th ed.; Wiley-Interscience: New York, 1988; p 562. ISBN 0-471-84997-9.
- ↑ Zintl, E.; Rienäcker, G. Über die Existenz eines flüchtigen Bromoxyds. Ber. Dtsch. Chem. Ges. B 1930, 63 (5), 1098–1104. DOI: 10.1002/cber.19300630516.
- ↑ Brenschede, W.; Schumacher, H.-J. Über die Darstellung und einige Eigenschaften eines Bromoxyds von der Formel Br2O. Z. Anorg. Allg. Chem. 1936, 226 (4), 370–84. DOI: 10.1002/zaac.19362260409.
- ↑ Schwarz, R.; Wiele, H. Über das Bromoxyd Br2O. Naturwissenschaften 1938, 26 (45), 742. DOI: 10.1007/BF01774152.
- ↑ Schwarz, Robert; Wiele, Heinz Zur Kenntnis der Bromoxyde (II. Mitteilung). J. Prakt. Chem. 1938, 152 (3–6), 157–76. DOI: 10.1002/prac.19391520306.
- ↑ 11.0 11.1 Campbell, C.; Jones, J. P. M.; Turner, J. J. Spectroscopic studies of bromine oxides: the infrared spectrum of solid bromide monoxide. Chem. Commun. (London) 1968 (15), 888–89. DOI: 10.1039/C19680000888.
- ↑ 12.0 12.1 Müller, Holger S. P.; Cohen, Edward A. Dibromine monoxide, Br2O: The rotational spectrum and molecular properties. J. Chem. Phys. 1997, 106 (20), 8344–54. DOI: 10.1063/1.473920.
- ↑ Tevault, D.; Walker, N.; Smardzewski, R.; Fox, W. Infrared spectra of the BrO and OBrO free radicals and of BrOBr and BrBrO molecules in Solid Argon at 10K. J. Phys. Chem. 1978, 82 (25), 2733–36. DOI: 10.1021/j100514a022.
- ↑ Allen, S. D.; Poliakoff, M.; Turner, J. J. Photochemistry of an ozone-bromine complex; the IR spectrum of matrix isolated Br2O. J. Mol. Struct. 1987, 157 (1–3), 1–15. DOI: 10.1016/0022-2860(87)87078-3.
- ↑ 15.0 15.1 Levason, William; Ogden, J. Steven; Spicer, Mark D.; Young, Nigel A. Characterization of dibromine monoxide (Br2O) by bromine K-edge EXAFS and IR spectroscopy. J. Am. Chem. Soc. 1990, 112 (3), 1019–22. DOI: 10.1021/ja00159a019.
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