# Selenourea > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Selenourea > Markdown URL: https://mediated.wiki/source/Selenourea.md > Source: https://en.wikipedia.org/wiki/Selenourea > Source revision: 1293925106 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Chembox | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 438233364 | ImageFile1 = Selenourea.svg | ImageName1 = Structural formula | ImageFile2 = Selenourea-3D-spacefill.png | ImageName2 = Space-filling model | ImageCaption2 = {{legend|black|[Carbon](/source/Carbon), C}}{{legend|white|[Hydrogen](/source/Hydrogen), H}}{{legend|blue|[Nitrogen](/source/Nitrogen), N}}{{legend|rgb(256, 160, 0)|[Selenium](/source/Selenium)}} | IUPACName = |Section1={{Chembox Identifiers | CASNo = 630-10-4 | CASNo_Ref = {{cascite|correct|chemspider}} | Beilstein = 1734744 | ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI = 36957 | ChEMBL = 3187603 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 10293781 | EINECS = 211-129-9 | Gmelin = 239756 | PubChem = 6327594 | RTECS = YU1820000 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = 0W506YR523 | UNNumber = 3283 3077 | InChI = 1/CH4N2Se/c2-1(3)4/h(H4,2,3,4) | InChIKey = IYKVLICPFCEZOF-UHFFFAOYAJ | StdInChI_Ref = {{stdinchicite|changed|chemspider}} | StdInChI = 1S/CH4N2Se/c2-1(3)4/h(H4,2,3,4) | StdInChIKey_Ref = {{stdinchicite|changed|chemspider}} | StdInChIKey = IYKVLICPFCEZOF-UHFFFAOYSA-N | MeSHName = C081959 | SMILES = NC(N)=[Se]}} |Section2={{Chembox Properties | Formula = {{chem2|SeC(NH2)2}} | C=1|H=4|N=2|Se=1 | Appearance = White solid; pink/grey solid when impure | MeltingPtC = 200 | BoilingPtC = 214 | Solubility =}} |Section7={{Chembox Hazards | GHSPictograms = {{GHS06}}{{GHS08}}{{GHS09}} | GHSSignalWord = Danger | HPhrases = {{H-phrases|301|331|373|410}} | PPhrases = {{P-phrases|260|261|264|270|271|273|301+310|304+340|311|314|321|330|391|403+233|405|501}} | MainHazards = }} | Section9 = {{Chembox Related | OtherCompounds = {{ubl|[Urea](/source/Urea)|[Thiourea](/source/Thiourea)}} }} }} '''Selenourea''' is the [organoselenium compound](/source/organoselenium_compound) with the [chemical formula](/source/chemical_formula) {{chem2|Se\dC(NH2)2|auto=1}}. It is a white solid. This compound features a rare example of a stable, unhindered [carbon](/source/carbon)-[selenium](/source/selenium) [double bond](/source/double_bond). The compound is used in the synthesis of selenium [heterocycle](/source/heterocycle)s. Selenourea is a selenium analog of [urea](/source/urea) {{chem2|O\dC(NH2)2}}. Few studies have been done on the compound due to the instability and toxicity of [selenium](/source/selenium) compounds.{{cite journal|last1=Koketsu |first1=M. |last2=Ishihara |first2=H. |title=Thiourea and selenourea and their applications |journal=Current Organic Synthesis |date=2006 |volume=3 |issue=4 |pages=439–455 |doi=10.2174/157017906778699521}} Selenourea is toxic if inhaled or consumed. ==Synthesis== The compound was first synthesized in 1884 by [Auguste Verneuil](/source/Auguste_Verneuil) by the reaction of [hydrogen selenide](/source/hydrogen_selenide) and [cyanamide](/source/cyanamide):{{cite journal|last=Hope |first=H. |title=Synthesis of selenourea |journal=Acta Chemica Scandinavica |date=1964 |volume=18 |page=1800 |doi=10.3891/acta.chem.scand.18-1800|doi-access=free}} :{{chem2|H2Se + N\tC\sNH2 → Se\dC(NH2)2}} While this reaction has even found use in industrial synthesis of selenourea,{{cite journal|last=Suvorov |first=V. |display-authors=etal |title=Production of selenourea of high purity |journal=Vysokochistye Veshchestva |date=1996 |volume=3 |pages=17–23}} more modern methods concern themselves with synthesis of substituted selenoureas. These can be synthesized using organic isoselenocyanates and secondary amines: :{{chem2|R\sN\dC\dSe + NHR′R″ → Se\dC(\sNHR)(\sNR′R″)}} Alternatively, [isocyanide](/source/isocyanide)s react with amines in the presence of elemental selenium:{{cite journal |doi=10.1021/jacs.6b11021 |title=A Library of Selenourea Precursors to PbSe Nanocrystals with Size Distributions near the Homogeneous Limit |date=2017 |last1=Campos |first1=Michael P. |last2=Hendricks |first2=Mark P. |last3=Beecher |first3=Alexander N. |last4=Walravens |first4=Willem |last5=Swain |first5=Robert A. |last6=Cleveland |first6=Gregory T. |last7=Hens |first7=Zeger |last8=Sfeir |first8=Matthew Y. |last9=Owen |first9=Jonathan S. |journal=Journal of the American Chemical Society |volume=139 |issue=6 |pages=2296–2305 |pmid=28103035 |osti=1437942 }} :{{chem2|RN\tC + R'2NH + Se -> R(H)NC(Se)NR'2}} ==Properties== [X-ray crystallographic](/source/x-ray_crystallography) measurements on [crystal](/source/crystal)s at −100 °C give average C=Se bond lengths of 1.86 [Å](/source/%C3%A5ngstr%C3%B6m), and 1.37 Å for C−N. Both the Se−C−N and N−C−N angles were measured at 120°, as expected for an [sp2-hybridized](/source/sp2_hybridization) carbon. Through these same studies, the existence of Se−H [hydrogen bonding](/source/hydrogen_bonding) in the [crystal lattice](/source/crystal_lattice)—suggested from the O−H and S−H hydrogen bonding found in crystals of [urea](/source/urea) and [thiourea](/source/thiourea)—was confirmed.{{cite journal|last1=Rutherford |first1=J. S. |last2=Calvo |first2=C. |title=The crystal structure of selenourea |journal=Zeitschrift für Kristallographie |date=1969 |volume=128 |issue=3–6 |pages=229–258 |doi=10.1524/zkri.1969.128.3-6.229|bibcode=1969ZK....128..229R |s2cid=98443594}} Both the shortened length of the N−C bond and the longer Se=C bond suggest a delocalization of the [lone pair](/source/lone_pair) on the amines; the Se=C [π-bonding](/source/Pi_bond) electrons are drawn towards the selenium atom, while the nitrogen's lone pair is drawn towards the [carbonyl](/source/carbonyl) carbon. A similar effect is observed in urea and thiourea. In going from urea to thiourea to selenourea the double bond is more delocalized and longer, while the C−N [σ bond](/source/Sigma_bond) is stronger and shorter. In terms of [resonance structure](/source/resonance_structure)s, the [selenol](/source/selenol) form (structures II, III) is more prevalent compared to urea and thiourea analogs; however, the lone pair the nitrogen of selenourea delocalizes only slightly more than the lone pair on thiourea (in contrast to a much greater delocalization in going from urea to thiourea).{{cite journal|last1=Hampson |first1=P. |last2=Mathias |first2=A. |title=Nitrogen-14 chemical shifts in ureas |journal=Journal of the Chemical Society B |date=1968 |volume=1968 |pages=673–675 |doi=10.1039/J29680000673}}. These minor differences suggest that the properties emergent from the delocalized nitrogen lone pair and destabilization of the C=S and C=Se π bond in thiourea and selenourea will also be similar. :File:Resonance.gif Unlike urea and thiourea, which have both been researched extensively, relatively few studies quantitatively characterize selenourea. While the [selone](/source/selone) tautomer (I) has been shown to be the more stable form,{{cite journal|last=Rostkowska |first=H. |display-authors=etal |title=Proton transfer processes in selenourea: UV-induced selenone → selenol photoreaction and ground state selenol → selone proton tunneling |journal=Chemical Physics |date=2004 |volume=298 |issue=1–3 |pages=223–232 |doi=10.1016/j.chemphys.2003.11.024|bibcode=2004CP....298..223R}} mainly qualitative and comparative information on selenourea's [tautomerization](/source/tautomerization) is available. In comparable manner to ketones, selones also tautomerize: :File:Selenourea_Tautomers.gif Since the greater delocalization of the lone pair electrons correlates with the selone product, the equilibrium position of selenourea likely has an [equilibrium position](/source/chemical_equilibrium) comparable to thiourea's (which is lies more to the right that than urea's). Thiourea has been shown to exist predominantly in its thione form at 42 °C in dilute [methanol](/source/methanol), with the thionol tautomer almost nonexistent at neutral [pH](/source/pH).{{cite journal|last1=Pramanick |first1=D. |last2=Chatterjee |first2=A. K. |title=Thiourea as a transfer agent in the radical polymerization of methyl methacrylate in aqueous solution at 42° |journal=European Polymer Journal |date=1980 |volume=16 |issue=9 |pages=895–899 |doi=10.1016/0014-3057(80)90122-6|bibcode=1980EurPJ..16..895P}} ==Reactivity== An important class of reactions of selenourea is the formation of [heterocycle](/source/heterocycle)s. Some selenium-containing heterocycles exhibit [antiinflammatory](/source/antiinflammatory) and [antitumor](/source/antitumor) activity, among other medicinal uses. Using selenourea as a precursor is considered to be the most efficient means of selenium-containing heterocyclic synthesis.{{cite journal|last1=Ninomiya |first1=M. |display-authors=etal |title=Selenium-containing heterocycles using selenoamides, selenoureas, selenazadienes, and isoselenocyanates |journal=Heterocycles |date=2010 |volume=81 |issue=9 |pages=2027–2055 |doi=10.3987/REV-10-677|doi-access=free }} Another class of reactions is the complexation of selenourea with [transition metal](/source/transition_metal)s and [metalloid](/source/metalloid)s. Its ability to act as an effective [ligand](/source/ligand) is attributed to the electron-donating effect of the amino groups and consequent stabilization of the selenium–metal [π bond](/source/pi_bond). In selenourea complexes only selenium–metal bonding has been observed, unlike in the urea and thiourea counterparts, which also bond through the nitrogen atom.{{cite journal|last1=Jones |first1=P. G. |last2=Thöne |first2=C. |title=Preparation, crystal structures and reactions of phosphine(selenourea)gold(I) complexes |journal=Chemische Berichte |date=1991 |volume=124 |pages=2725–2729 |doi=10.1002/cber.19911241213}} ==References== {{Reflist|30em}} Category:Organoselenium compounds Category:Ureas Category:Selenium(−II) compounds --- Adapted from the Wikipedia article [Selenourea](https://en.wikipedia.org/wiki/Selenourea) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Selenourea?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.