Cyclo-thiazenokomplexe von Molybdän und Wolfram. Die Kristallstruktur von AsPh4[WCl4(N3S2)] / Cyclo-thiazeno Complexes of Molybdenum and Tungsten. The Crystal Structure of AsPh4[WCl4(N3S2)]

Abstract

The dark brown cyclo-thiazeno com plexes [MoCl3(N3S2)]2 and [WCl3(N3S2)]2 are obtained by quantitative reactions of MoNCl3 with (NSCl)3 and of WOCl4 or WSCl4 with excess (NSCl)3, respectively. They are diamagnetic, thermally stable up to 200 °C, and only slightly sensitive towards moist air, but react explosively with aqueous bases. According to the IR spectra [MoCl3(N3S2)]2 is dimerized via chloro bridges whereas the tungsten com pound is associated via the γ-nitrogen atoms of the cyclo-thiazeno ligand. By reaction with [AsPh4]Cl or [PPh4]Cl in CH2Cl2, the compounds EPh4[MCl4(N3S2)] are obtained (E = P, As; M = Mo, W). The crystal structure of AsPh4[WCl4(N3S2)] was determined from X-ray diffraction data (1845 observed reflexions, R = 0.045). It crystallizes in the monoclinic space group P21/c with four formula units per unit cell. The lattice constants are a = 1352.4, b = 968.4, c = 2393.8 pm and β = 115.1°. The com pound is built up from AsPh4 ⊕ cations and [WCl4(N3S2)]⊖ anions in which the W atoms are coordinated in a distorted octahedral fashion by four Cl and two N atoms of the N3S2 ligand. The WN bond lengths (182 and 188 pm) correspond to douple bonds. The WN3S2 ring is planar and has SN bond lengths between 154 and 161 pm.