thioketone

The C=S bond length of thiobenzophenone is 1.63 Å, which is comparable to 1.64 Å, the C=S bond length of thioformaldehyde, measured in the gas phase. Due to steric interactions, the phenyl groups are not coplanar and the dihedral angle SC-CC is 36°. Unhindered dialkylthiones polymerize or oligomerize but thiocamphor is well characterized red solid.{{cite journal |doi=10.1524/zkri.217.2.83.20627|title=Crystal Structures of R-Thiocamphor |year=2002 |last1=Brunelli |first1=M. |last2=Fitch |first2=A. N. |last3=Mora |first3=A. J. |journal=Zeitschrift für Kristallographie - Crystalline Materials |volume=217 |issue=2 |pages=83–87 |bibcode=2002ZK....217...83B |s2cid=97935620 }}

File:Ph2CS.JPG

Consistent with the double bond rule, most alkyl thioketones are unstable with respect to dimerization.Organosulfur Chemistry I: Topics in Current Chemistry, 1999, Volume 204/1999, 127-181, {{doi|10.1007/3-540-48956-8_2}} The energy difference between the p orbitals of sulfur and carbon is greater than that between oxygen and carbon in ketones.Fisera, L.; Huisgen, R.; Kalwinsch, I.; Langhals, E.; Li, X.; Mloston, G.; Polborn, K.; Rapp, J.; Sicking, W.; Sustmann, R. "New Thione Chemistry". Pure Appl. Chem., 1996, 68, 789-798. {{doi|10.1351/pac199668040789}} The relative difference in energy and diffusity of the atomic orbitals of sulfur compared with carbon results in poor overlap of the atomic orbitals and the energy gap between the HOMO and LUMO is thus reduced for C=S molecular orbitals relative to C=O.Sustmann, R.; Sicking, W.; Huisgen, R. "A Computational Study of the Cycloaddition of Thiobenzophenone S-Methylide to Thiobenzophenone". J. Am. Chem. Soc. 2003, 125, 14425-14434. {{doi|10.1021/ja0377551}} The striking blue appearance of thiobenzophenone is attributed to π→ π* transitions upon the absorption of red light. Thiocamphor is red.

Thiones are usually prepared from ketones using reagents that exchange S and O atoms. A common reagent is phosphorus pentasulfide,{{cite journal|first1=Vivek |last1=Polshettiwar |first2=M. P. |last2=Kaushik |title=A new, efficient and simple method for the thionation of ketones to thioketones using P₄S₁₀/Al₂O₃ |journal=Tetrahedron Letters |date=2004 |volume=45 |issue=33 |pages=6255–6257 |doi=10.1016/j.tetlet.2004.06.091}} although that reagent also tends to induce side-reactions.{{rp|928}} Lawesson's reagent is related. Other methods uses a mixture of hydrogen chloride combined with hydrogen sulfide. Bis(trimethylsilyl)sulfide has also been employed.{{Cite journal| last1 = Mcgregor | first1 = W. M.| last2 = Sherrington | first2 = D. C.| title = Some recent synthetic routes to thioketones and thioaldehydes| journal = Chemical Society Reviews| volume = 22| issue = 3| pages = 199| year = 1993 | doi = 10.1039/CS9932200199}} Thiones can also be prepared from geminal dichlorides,{{cite book|title=The Chemistry of the Carbonyl Group|editor-first=Saul|editor-last=Patai|orig-date=1966|publisher=Interscience|location=Chichester|lccn=66-18177|isbn=0-470-66920-9|year=1979|first=E.|last=Campaigne|series=The Chemistry of Functional Groups|chapter=Thioketones}}{{rp|927}} but geminal dichlorides are typically prepared from ketones as well.

There are no general methods to oxidize methylene groups to thioketones,{{rp|pp=929-930}} reflecting sulfur's comparable electronegativity to carbon.

Thiobenzophenone [(C₆H₅)₂CS] is a stable deep blue compound that dissolves readily in organic solvents. It photooxidizes in air to benzophenone and sulfur. Since its discovery, a variety of related thiones have been prepared.{{Cite journal| pages = 625–630| issue = 9| year = 2000| pmid = 10995200 | doi = 10.1021/ar980073b| volume = 33| journal = Accounts of Chemical Research| last1 = Okazaki | first1 = R.| last2 = Tokitoh | first2 = N.| title = Heavy ketones, the heavier element congeners of a ketone}}

Thiosulfines, also called thiocarbonyl S-sulfides, are compounds with the formula R₂CSS. Although superficially appearing to be cumulenes, with the linkage R₂C=S=S, they are more usefully classified as 1,3-dipoles and indeed participate in 1,3-dipolar cycloadditions. Thiosulfines are proposed to exist in equilibrium with dithiiranes, three-membered CS₂ rings. Thiosulfines are often invoked as intermediates in mechanistic discussions of the chemistry of thiones. For example, thiobenzophenone decomposes upon oxidation to the 1,2,4-trithiolane (Ph₂C)₂S₃, which arises via the cycloaddition of Ph₂CSS to its parent Ph₂CS.{{cite journal|author1 =Rolf Huisgen|author-link =Rolf Huisgen|author2 = J. Rapp |title=1,3-Dipolar Cycloadditions. 98. The Chemistry of Thiocarbonyl S-Sulfides |journal=Tetrahedron |date=1997 |volume=53 |issue=3 |pages=939–960 |doi=10.1016/S0040-4020(96)01068-X}}

• {{Cite journal| pages = 265–269| year = 1974 | doi = 10.1016/0009-2614(74)85029-3| issue = 2| volume = 29 | first1 = H.| last2 = Landsberg | first2 = B. M.| last3 = Suffolk | first3 = R. J.| last4 = Vodden | first4 = A.| title = The photoelectron and microwave spectra of the unstable species thioacetaldehyde, CH₃CHS, and thioacetone, (CH₃)₂CS| journal = Chemical Physics Letters| last1 = Kroto|bibcode = 1974CPL....29..265K }}
• {{cite book |doi=10.1016/B0-08-044655-8/00053-2 |chapter=Thioaldehydes and Thioketones |title=Comprehensive Organic Functional Group Transformations II |date=2005 |last1=Cooper |first1=N.J. |pages=355–396 |isbn=978-0-08-044655-4 }}
• {{cite journal |doi=10.1007/s41061-018-0209-0 |title=The Construction and Application of C=S Bonds |date=2018 |last1=Murai |first1=Toshiaki |journal=Topics in Current Chemistry |volume=376 |issue=4 |page=31 |pmid=29987439 |s2cid=51605664 }}

• Thial, for a description of thioaldehydes.
• Thioketene
• Sulfene
• Selone (often called selenone)

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Category:Functional groups