%0 Journal Article %A Selzer, Tzvia %A Rappoport, Zvi %D 1996 %T Bis(dimesitylmethylene)-1,3-dithietane, -1,2,4-trithiane, and -1,2,4,5-tetrathiane. Conformation and DNMR Study. Observable Dimesityl Thioketene %U https://acs.figshare.com/articles/journal_contribution/Bis_dimesitylmethylene_-1_3-dithietane_-1_2_4-trithiane_and_-1_2_4_5-tetrathiane_Conformation_and_DNMR_Study_Observable_Dimesityl_Thioketene/3703158 %R 10.1021/jo960911k.s001 %2 https://ndownloader.figshare.com/files/5793600 %K P 2 S 5 %K Observable Dimesityl Thioketene %K kcal mol %K dimesityl thioketene 2 %K tetrathiane ring %K signal %K dimesityl ketene %K propeller conformation %K analog %K bi %K Static NMR data %K dimesitylmethylene moieties %K Ditipylketene forms %K DNMR Study %K enantiomer %K meso form %K 160 K %K threshold barriers %K Diphenylacetyl chloride %X The reaction of dimesityl ketene with P2S5 and pyridine gives 2,4-bis(dimesitylmethylene)-1,3-dithietane (3), 3,6-bis(dimesitylmethylene)-1,2,4,5-tetrathiane (4), 3,5-bis(dimesitylmethylene)-1,2,4-trithiane (5), and dimesityl thioketene 2 as a transient. The structures of 3 and 4 were determined by X-ray crystallography. The dimesitylmethylene moieties in 3 and 4 have a propeller conformation, and the tetrathiane ring in 4 has a twist-boat conformation. Static NMR data are consistent with the presence of two enantiomers and one meso form for 3 and of three pairs of enantiomers for 4. The several aromatic signals observed for 3 and 4 at slow exchange at 160 K coalesce to a single signal at higher temperatures. The threshold barriers for these dynamic processes are 12.7 (3) and 13.3 (4) kcal mol-1, and the dynamic behavior was analyzed in terms of flip processes. On standing, a solution of 3 develops a blue color which is attributed to formation of 2, by retro-dimerization of 3. Diphenylacetyl chloride gives with P2S5 the analog of 5 and its one-double bond reduction product. Ditipylketene forms a product identified tentatively as the analog of 3. %I ACS Publications