The synthesis of poly(sulphur nitride) and some novel 4-phenyl-1,2,3,5-dithiadiazolium compounds

Abstract

[S(-5)N(_5)]Cl has been reacted with a wide variety of reducing agents leading to a new non-explosive route to high quality powdered (SN)x. Data collected from these reductions has led to a new mechanistic proposal for the formation of the powdered polymer. The vacuum thermolysis of [S(_5)N(_5)Cl with Li(_3)N produced S(_2)N(_2) in low yield. The new supporting electrolyte, [Bu(_4)N]AsF(_6), was prepared, and has a greater scanning window in SO(_2) compared with any others previously reported. S(_5)N(_5)ASF(_6) has been produced in high purity and is much less moisture and oxygen sensitive than any other S(_5)N(_5) salts previously prepared. The new supporting electrolyte, [Bu(_4)N]AsF(_6), in conjunction with [Bu(_4)N]BF(_4), was used to study the electrochemistry of S(_5)N(_5)AsF(_6). [SN]AsF(_6), [S(_4)N(_3)]BF(_4), S(-2)N(_2) and [PhCN(_2)S(_2)][S(_3)N(_3)] by cyclic voltammetry. Electroreduction of both S(_5)N(_5)AsF(_6) and [SN]AsF(_6) produced conducting forms of (SN)x containing AsF(_6) , the latter product having a molecular formula of approximately S(_5)N(_5)AsF(_6). Exhaustive electrolysis of [S(_5)N(_5)]BF(_4) showed the breakdown of BF(_4) anion, producing BF(_3), which was seen as the CH(_3)CN-BF(_3) adduct, and F(^.) which reacted with the solvent, SO(_2), to produce SO(_2)F(_2); the S(_4)N(_4)(^.)S0(_3) adduct was also produced. Reduction of [S(_5)N(_5)]Cl by (PhCN(_2)S(_2))(_2) produced [[PhCN(_2)S(_2)](_2)Cl][S(_3)N(_3)],(I) , in CH(_3)CN and [PhCN(_2)S(_2)][S(_3)N(_3)], (II), in pentane. Reduction of [S(_4)N(_3)]C1 by (PhCN(_2)S(_2))(_2) in CH(_3)CN produced [PhCN(_2)S(_2)] [S(_3)N(_2)]C1, (III). X-ray structure determination has given accurate structures for all three compounds. (I), (II) and (III) were all successfully prepared in high yields. Large crystals of ( II) were prepared from the reaction between [S(_5)N(_5)]AlC1(_4) and (PhCN(_2)S(_2))(_2) in SO(_2), and were shown to contain some free [PhCN(_2)S(_2)]' monomers by e.s.r. spectroscopy. When vapours of (SN)x and (PhCN(_2)S(_2))(_2) were mixed together ( II) was produced adding further evidence for S(_3)N(_3)' being the major vapour phase species of (SN)x. Another e.s.r. active species, [PhCN(_2)S(_2)](_2)Cl (IV), was produced from the solid state reaction between ½(PhCN(_2)S(_2))(_2) and [PhCN(_2)S(_2)]Cl. (I),(II) , (III) and (IV) were all subjected to a low temperature D.C. nitrogen plasma, producing (PhCN(_3)S(_2))(_2), except for (IV) which decomposed to form [PhCN(_2)S(_2)]CI and a black non-conductive polymer.