Poly(sulphur nitride): an assessment of the synthesis from trichlorocyclotri(azathiene) and trimethylsilyl azide

Abstract

An improved synthesis and purification, and some properties, of powdered (SN)_X are reported. Gram quantities can be prepared by reacting (NSCl)₃ and Me₃SiN₃(molar ratio 1:7.5) in acetonitrile, followed by the liquid-SO₂ extraction of impurities. The product polymers are fine black powders; surface areas (14–22 m² g^–1) were measured by the B.E.T. method. Freshly prepared and purified samples readily converted to S₄N₄ both photolytically and by thermal activation; a rapid solid-state conversion to S₄N₄ occurred at ca. 120 °C (under N₂). Differential scanning calorimetry gave ΔH(conversion)=–(20 ± 1) kJ mol^–1 of S₄N₄. Aged samples of powdered polymer were sublimed in vacuo at 110 °C to give gold-bronze conductive layers, σ(bulk)≈ 5 Ω^–1 cm^–1. A new mode of growth of (SN)_X single crystals during high-vacuum sublimation was observed.