Cyclic and Heterocyclic Thiazenes

Abstract

Scheme I1A second binary compound, tetrasulfur dinitride (S4N2, 4), was also isolated before the end of the last century (32). Its correct elemental composition, however, was not established until 1925 (33), and its molecular formula not confirmed until 1951 (34). Early estimates suggested the formula N2Sj (32), an observation that attests to the tendency of the molecule to disproportionate above its melting point of 22.5"C (hence, the high sulfur content). The six-membered ring structure with a half-chair conformation was finally confirmed in 1981 (35,36). Most early preparative methods involved a thermal decomposition, for example, of S4N, in the presence of sulfur and/or carbon disulfide (37,38). More recently the use of simple metathetical reactions, for example, between Ni(S2N2H)? and S2CI2 has been explored (39). A simple procedure involving the reaction of aqueous ammonia with sulfur monochloride has also been developed (40); although the yield is low (<2%), the method provides a convenient preparation of small quantities (<0.5 g) starting from commercially available materials (3%). The solid state polymerization of S4N2 to (SN), ( 5 ) has recently been reported (36); this process is presumably initiated by trace amounts of (radical) impurities since, when recrystallized from diethyl ether, solid S,N, is indefinitely stable below its melting point (3%).Disulfur dinitride (6) (Scheme 11) was first generated (inadvertently) by Burt in 1910 (41) during an attempt to remove sulfur impurities from SJNJ by passing a vaporous mixture of the two over finely divided silver. At the time he noted the formation of a blue film [later characterized as (SN), polymer]. This reaction has been studied extensively since then, and now 304 RICHARD T. OAKLEY

Interactive Radical Dimers in Photoconductive Organic Thin Films

“…The thiazyl radical family demonstrates chemical stability and strong intermolecular interactions, and has been shown to have various interesting properties. [11][12][13][14][15][16] Since BDTDA is a so-called disjoint diradical, the molecular orbitals for the two unpaired electrons are localized on separate five-membered rings and the exchange interactions between the two radical centers are very small. [10] The crystal structure of BDTDA in fact consists of a face-to-face BDTDA dimer, which reflects the fact that the intermolecular interaction is stronger than the intramolecular interaction.…”

A Variable Temperature X-ray Diffraction Investigation of [PPN+][S4N5−]: Supramolecular Interactions Governing an Order/Disorder Transformation and the First High Resolution X-ray Structure of the Anion

“…However, another possibility needs to be considered (Scheme 1) since it is now well-established that 1,3-nitrogen shift reactions are possible for many sulfur-nitrogen rings and cages [2]. This was first discovered from the scrambling of 15 N labels introduced into PhCN 5 S 3 [53,54] and also found as the operative mechanism for the transformation of this same type of cage molecule into trithiatetrazocines under nucleophilic attack [55].…”

“…Amongst the binary sulfur-nitrides, virtually all of which are endoergic, the sulfur-nitrogen anions are particularly noted for their instability with an enhanced tendency to decompose explosively [1,2,3]. The use of large cations was recognized early on in this chemistry as a mitigating factor in the stability of their salts [4].…”

Experimental and Computational Evidence for “Double Pancake Bonds”: The Role of Dispersion-Corrected DFT Methods in Strongly Dimerized 5-Aryl-1λ2,3λ2-dithia-2,4,6-triazines

“…However, the essence of the idea was captured much earlier by “diffuse π*−π* overlap” to explain many interactions in electron-rich, unsaturated thiazyl (i.e., −S · =N−) compounds. 32 As introduced, this concept was a unifying framework for many interactions between such electron-rich unsaturated moieties, whether diamagnetic or paramagnetic (for example, it rationalizes the formation of transannular short contacts in thiazyl cage compounds such as the paradigmatic S 4 N 4 structure). 31 Significantly, diffuse π*−π* overlap was also used to develop the dimerization of the (formally antiaromatic) 8π 5-phenyl-1λ 2 ,3λ 2 -dithia-2,4,6-triazine, wherein the very short transannular contacts were rationalized through four-electron multicenter (4 e /mc) interactions (Figure 1).…”