{{Chembox | ImageFile = Dithiete.svg | ImageFile_Ref = {{chemboximage|correct|??}} | ImageSize = 100 | ImageName = Kekulé, skeletal formula of dithiete with all explicit hydrogens added | PIN = 1,2-Dithiete | SystematicName = 1,2-Dithiacyclobut-3-ene | OtherNames = Dithiete<br />Dithiacyclobutene<br />1,2-Dithia[4]annulene |Section1={{Chembox Identifiers | CASNo = 7092-01-5 | PubChem = 138918 | ChemSpiderID = 122516 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | SMILES = c1css1 | SMILES1 = S1SC=C1 | StdInChI = 1S/C2H2S2/c1-2-4-3-1/h1-2H | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = CTGHONDBXRRMRC-UHFFFAOYSA-N | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} }} |Section2={{Chembox Properties | C=2 | H=2 | S=2 }} |Section3={{Chembox Related | OtherFunction_label = thietes | OtherFunction = Thiete | OtherCompounds = {{Unbulleted list|Thiirene|2,3-Dihydrothiophene|Thiophene}} }} }}

'''Dithiete''' is an unsaturated heterocyclic compound that contains two adjacent sulfur atoms and two sp<sup>2</sup>-hybridized carbon centers. Derivatives are known collectively as dithietes or 1,2-dithietes. With 6 π electrons, 1,2-dithietes are examples of aromatic organosulfur compounds. A few 1,2-dithietes have been isolated;<ref>{{cite book |last=Drabowicz |first=J |author2=Lewkowski, J |author3=Kudelska, W |author4= Zając, A |chapter=Four-membered Rings with Two Sulfur Atoms |title=Comprehensive Heterocyclic Chemistry III |year=2008 |volume=2 |pages=811–852 |doi=10.1016/B978-008044992-0.00218-2|isbn=978-0-08-044992-0 }}</ref><ref>{{cite journal | author1 = Donahue, JP | author2 = Holm, RH | title = 3,4-Bis(1-adamantyl)-1,2-dithiete: the First Structurally Characterized Dithiete Unsupported by a Ring or Benzenoid Frame | journal = Acta Crystallographica | year = 1998 | volume = C54 | pages = 1175–1178 | doi = 10.1107/S0108270198002935 | issue = 8 | pmid = 9760719| bibcode = 1998AcCrC..54.1175D }}</ref> one (low-yielding) route is oxidation of a dithiolene complex.<ref name=":0" />

thumb|left|194px|Structure of the dithiete S<sub>2</sub>C<sub>2</sub>(CO<sub>2</sub>Me)<sub>2</sub>. Selected distances and angles: r<sub>C=C</sub> = 1.362, r<sub>C-S</sub> = 1.738, r<sub>S-S</sub> = 2.072 Å, <<sub>S-S-C</sub> = 78.3°, <<sub>S-C-S</sub> = 102°.<ref name=":0">{{cite journal|title=Synthesis, Structure, and Ring Conversion of 1,2-Dithiete and Related Compounds|journal=J. Org. Chem.|year=1998|volume=63|pages=8192–8199|author=T. Shimizu |author2=H. Murakami |author3=Y. Kobayashi |author4=K. Iwata |author5=N. Kamigata | issue=23 |doi=10.1021/jo9806714}}</ref> Computation suggests that electron-donating substituents tend to promote isomerization to the vicinal dithione, and conversely electron-withdrawing substituents stabilize the dithiete. 3,4-Bis(trifluoromethyl)-1,2-dithiete is a particularly stable example, arising from boiling the corresponding alkyne in sulfur.<ref name=DS>{{cite book|pp=625&ndash;626,628&ndash;629|doi=10.1002/9780470187203|title=Small Ring Heterocycles|volume=3|chapter=Four‐membered sulfur heterocycles|first1=D. C.|last1=Dittmer|first2=T. C.|last2=Sedergran|series=Chemistry of Heterocyclic Compounds|year=1985|publisher=Wiley|isbn=9780471056249}}</ref> Empirically, bulky neighboring groups, even when electron-donating also force the equilibrium towards the dithiete conformer. Absent either of these effects, "most of the 1,2-dithietes are highly reactive and elude isolation at room temperature."<ref name=Z>{{cite book |last=Zoller |first=U |title=Comprehensive Heterocyclic Chemistry II |year=1996 |isbn=978-0-08-096518-5 |volume=1B |pages=1113–1138 |chapter=Four-membered Rings with Two Sulfur Atoms |doi=10.1016/B978-008096518-5.00035-6}}</ref>{{rp|1131}}

Ring opening is facile, even with stabilized dithietes, and occurs in many reactions.<ref name=DS/> For example 3,4-bis(trifluoromethyl)-1,2-dithiete undergoes a hetero-Diels-Alder reaction with tetramethylethylene, indicating that a diene (thione) form must be the active intermediate. Metals and trivalent phosphorus derivatives insert into the ring/reduce the dithione tautomer to give metal dithiolene complexes.<ref name=Z/>{{rp|1131}}

Unsubstituted 1,2-dithiete has been generated in thermolytic reactions and was characterized by microwave spectroscopy, ultraviolet photoelectron spectroscopy and infrared spectroscopy in a low temperature matrix. The open ring isomer, dithioglyoxal, HC(S)C(S)H, is less stable than the 1,2-dithiete.<ref>{{Cite journal| author1 = Reinhard Schulz| author2 = Armin Schweig| author3 = Klaus Hartke| author4 = Joachim Koester| title = Theory and application of photoelectron spectroscopy. 100. Variable-temperature photoelectron spectral study of 1,3-dithiol-2-one and 4,5-disubstituted 1,3-dithiol-2-ones. Thermal generation of 1,2-dithiete, 3,4-disubstituted 1,2-dithietes, and dialkyl tetrathiooxalates| journal = Journal of the American Chemical Society| volume = 105| issue = 14| pages = 4519–4528| year = 1983 | doi = 10.1021/ja00352a004| bibcode = 1983JAChS.105.4519S}}</ref> The dithione can be prepared (as ''trans''-dithioglyoxal) by low temperature photolysis of 1,3-dithiol-2-one.<ref>{{cite journal | author1 = Mucha, M | author2 = Pagacza, M | author3 = Mielke, Z | title = Infrared detection of dithioglyoxal from photolysis of 1,3-dithiol-2-one in solid argon and nitrogen | journal = Chemical Physics Letters | volume = 458 | issue = 1–3 | date = 6 June 2008 | pages = 39–43 | doi = 10.1016/j.cplett.2008.04.088 |bibcode = 2008CPL...458...39M }}</ref> Quantum chemical calculations reproduce the observed greater stability of 1,2-dithiete only if large basis-sets with polarization functions are used.<ref>{{cite journal | author1 =Frolov, YV | author2 = Vashchenko, AV | author3 = Mal'kina, AG| author4 = Trofimov, BA| title = ''Ab initio'' quantum-chemical calculations of the energies and structures of 1,2-acetylenedithiol isomers | journal =Journal of Structural Chemistry | year = 2009| volume = 50| issue = 2 | pages = 195–200 | doi = 10.1007/s10947-009-0029-8| bibcode = 2009JStCh..50..195F | s2cid = 93780466}}</ref>

==See also== * Dithietane - the corresponding saturated ring * Thiete - an analogue with only one sulfur atom

==Additional reading <!--how many calculations do we need?-->== *{{cite journal | last1 = Diehl | first1 = F. | first2 = H. | last2 = Meyer | first3 = A. | last3 = Schweig | first4 = B. A. | last4 = Hess | first5 = J. | last5 = Fabian | date=September 1989 | title = 1,2-Dithiete is more stable than 1,2-dithioglyoxal as evidenced by a combined experimental and theoretical IR spectroscopic approach | journal = J. Am. Chem. Soc. | volume = 111 | issue = 19 | pages = 7651–7653 | doi = 10.1021/ja00201a076 | bibcode = 1989JAChS.111.7651D }} *{{cite journal | author1 =Vijay, D| author2 =Priyakumar, UD| author3 =Sastry, GN| title = Basis set and method dependence of the relative energies of C<sub>2</sub>S<sub>2</sub>H<sub>2</sub> isomers| journal =Chemical Physics Letters | year = 2004| volume = 383| issue = 1–2 | pages = 192–197 | doi= 10.1016/j.cplett.2003.11.021|bibcode = 2004CPL...383..192V }} *{{cite journal | author1 = Jonas, V | author2 = Frenking, G | title = On the crucial importance of polarization functions for the calculation of molecules with third-row elements: the conformations of chlorocarbonyl isocyanate ClC(O)NCO and the equilibrium of 1,2-dithioglyoxal with its cyclic isomer 1,2-dithiete | journal = Chemical Physics Letters | year = 1991 | volume = 177 | issue = 2 | pages = 175–183 | doi = 10.1016/0009-2614(91)90064-G |bibcode = 1991CPL...177..175J }} *{{cite journal | author1 = Gonzalez, L | author2 = Mo, O | author3 = Yanez, M | title = High-level ''ab initio'' calculations on the 1,2-dithioglyoxal/1,2-dithiete isomerism | journal = Chemical Physics Letters | volume = 263 | issue = 3 | date = 13 December 1996 | pages = 407–413(7) | doi = 10.1016/S0009-2614(96)01240-7 | bibcode=1996CPL...263..407G}}

==References== {{reflist}}

Category:Organic disulfides Category:Sulfur heterocycles Category:Four-membered rings