Aryl 1,5-dithia-2,4,6,8-tetrazocines. A synthetic, electrochemical, and structural investigation

Abstract

New preparative routes to the title compounds are reported in which the yields are substantially improved over previous methods. In one method, reaction of O2 with a mixture of XC6H,CN2S2+~1-and Ph,Sb leads to the products in 40-60% yield. In another, the reaction of the same salts with silylated amidines XC6H4C{NSiMe3}N(SiMe3)2 in a 1 : 1 mol ratio leads to the same compounds in 18-65% yield. The syntheses of 3,7-(XC6H,)2{CN2S2N,C), X = H, 4-CH,, 4-CH,O, 4 4 , 4-CF,, and 3-CF,, are reported. Mixed derivatives were also prepared, but not isolated as pure compounds. The crystal structure of the 4-CF, compound has been determined by X-ray diffraction; triclinic, with Z = 1; cell dimensions: a = 6.835(2), b = 9.936(3), c = 6.320(2) A , a = 96.44(3)", P = 102.88(3)", y = 88.42(3)". R = 3.4%, R,,. = 3.5% for 1100 data. The eight-membered ring is flat with equivalent bond lengths between any two types of atoms, indicative of a delocalized electron distribution. ' The 10a central aromatic rings have been oxidized and reduced in CHzC1, using voltammetric methods. The reversible one-electron reduction step gives stable 1 l n species. On a dCveloppC de nouvelles voies de synthkse des compos6s mentionnes dans le titre qui donnent des rendements de beaucoup superieurs 2 ceux rapportes anterieurement. Dans une mCthode, la rCaction du O2 avec un melange de HC6H4CN2S2+C1-et de Ph3Sb conduit aux produits avec des rendements allant de 40 a 60%. Dans une autre mCthode, la reaction des mCmes sels avec les amidines silylkes XC6H,C{NSiMe,}N(SiMe,),, dans un rapport molaire de 1 : 1, conduit aux mCmes produits avec des rendements allant de 18 a 65%. Donc on rapporte la synthkse des 3,7-(XC6H,)2{CN2S2N2C), X = H, 4-CH,, 4-CH,O, 4-C1, 4-CF3 et 3-CF3. On a aussi prepare des derives mixtes; toutefois, il n'a pas Cte possible de les isqler 2 I'Ctat pur. On a determine la structure cristallin: du compose 4-CF, par diffraction des rayons X; triclinique, P l , avec a = 8,835(2), b = 9,936(3) et c = 6,320(2) A , a = 96,44(3)", P = 102,88(3)" et y = 88,42(3)", Z = 1. R = 3,4% et R,, = 3.5% pour I100 donnCes. Le cycle a huit chainons est plat alors que les longueurs des liaisons sont Cquivalentes entre tous les atomes pris deux a deux; ce resultat indique que la distribution Clectronique est dClocalisCe. Utilisant des methodes voltampCrometriques et operant dans le CH2C1,, on a oxydC et reduit les cycles aromatiques 2 10 Clectrons a . La reduction reversible par un electron conduit a des espkces stables a 11 electrons n . En accord avec les etudes chimiques anterieures, les composCs mentionnes dans le titre sont beaucoup plus difficiles a oxyger que le 3,7-[(CH3)2Nl2{CNzSzNzC}.[Traduit par la redaction]

Electrochemistry of methylidyne and 1,2,3,5-dithiadiazole complexes of iron and nickel and a reinterpretation of the composition of "PhCN2S2Fe2(CO)6"

“…Clusters 2 provide well-resolved NMR spectra typical for diamagnetic species, i.e., without paramagnetic line broadening or unusual chemical shifts (5), whereas the parent dithiadiazole radicals 4 show broad featureless NMR spectra consistent with their paramagnetism. The 'H and I3c chemical shifts (Table 3) are within the range observed for a wide variety of aryl-C(NS-), compounds that we have previously studied (8). The samples of 4 were sealed under vacuum to prevent the facile reaction with oxygen (8a).…”

Structural studies of dithiatetrazocines: X-ray crystal structures of the symmetric dithiatetrazocines p-XC6H4CN4S2CC6H4X [X = NO2, Br] and the first unsymmetric dithiatetrazocine, p-BrC6H4CN4S2CC6H4NO2

“…They recovered a mixture of symmetrically substituted products (14.5%) and unsymmetrically substituted products (3%) in a non-statistical ratio. Subsequent studies by Boeré et al (9) showed that unsymmetric dithiatetrazocines can be prepared by reaction of a dithiadiazolylium chloride salt with the silylated amidine in the minimum volume of refluxing MeCN. This scrambling reaction led to a statistical distribution of products (i.e., 50% unsymmetric product).…”

“…In our current studies, we utilized an alternative preparative route to DTTA rings, also developed by Boeré et al (9). The two dithiadiazolylium salts, [p-BrC 6 H 4 CNSSN]Cl and [p-O 2 NC 6 H 4 CNSSN]Cl, were prepared according to the literature method (17).…”

“…A series of crystallographic studies have revealed two different geometries possible for the dithiatetrazocine ring, either a planar 10p aromatic structure (8,9) with a nonbonding transannular S···S contact (A) or a folded structure (8,10) with a long S-S bond (B).…”

“…Electrochemical studies (9) indicate that the planar dithiatetrazocines are quite resistant to oxidation and, for example, attempted oxidation (at S) using MCPBA or N 2 O 4 proved unsuccessful (8,13). This is, perhaps, surprising, given the isolation of both the S IV and S VI derivatives i.e., SR and S(O)R by other synthetic methods (14).…”