dure to give an insoluble black powder with an IR spectrum in good agreement with that reported by Dehnicke et a1. ['] The insolubility of this black powder in organic solvents and in liquid SO, and the possibility of combine to make its characterization by spectroscopic methods (e.g. NMR) difficult. However, complete elemental analyses are consistent with the formula Se,N,CI, rather than Se4N,.1'4% 15] Furthermore, when the reaction is carried out with the stoichiometry indicated in Equation (a), the 'HNMR spectrum of the filtrate reveals the presence of unchanged Me,SiN, (6 = 0.26). When the stoichiometry is adjusted to that shown in Equation (b), Me,SiN, is com-3 Se,CI, + 2 Me,SiN, -2 Se,N,Cl, + 2 Me,SiCl + N, (b) Id pletely consumed, and the 'H NMR spectrum shows only Me3SiC1 (6 = 0.41). The yield of Se,N,Cl, (found: C1, 19.75; Se, 70.00) is approximately 70% after 16 h. Compound Id may also be prepared in high yield by the reaction of bis[bis(trimethylsilyl)arnin~]selane[~~~ with a mixture of selenium halides designed to mimic "SeCI," in dichloromethane [Eq. (c)]. The 'H NMR spectrum of the 3 [(Me,Si),N),Se + 4 SeCI, + Se,CI, -3 Se,N,Cl, +12 Me,SiCI
Id
filtrate revealed that Me,SiCI (6 = 0.39) is the exclusive proton-containing product of this reaction, which proceeds according to Equation (c) to give analytically pure samples of Se,N,Cl, (Id). The infrared spectra of the products obtained from the reactions (a), (b), and (c) are identical.
The synthesis of Se,N,CI, completes the series l a -l d in which one of the sulfur atoms of l a is successively replaced by selenium. Although l b and l c are represented as ionic, we note that covalent forms of both derivatives have been structurally characterized.13s41 Thus Id may also exist in both covalent and ionic forms. The thermal instability of Id relative to the other members of the series is probably due to the presence of the labile NSeN group in Id and, as mentioned earlier," 51 samples should be stored at low temperatures to avoid loss of chlorine.
Finally, we note that attempts to convert Se,N,Cl, to the known compound Se3N2211 by reaction with AgAsF, in liquid SO,, or to prepare Se,N,Cl+ salts by the treatment of Se,N,Cl, with chloride ion acceptors in dichloromethane or liquid SO,, were unsuccessful, probably due to the insolubility of Se,N,Cl, in these solvents.
Experimental Procedure
A solution of [(Me,Si),N,]Se [17] (0.200 g, 0.5 mmol) in CH,CI, (5 mL) was added to a mixture of Se,CI, (0.0345 g, 0.15 mmol) and SeCI, (0.143 g, 0.65 mmol) in CH,CI, (20 mL) at -78 "C under a dry nitrogen atmosphere. The dark red solution was allowed to warm to room temperature (20 h) and gave a black precipitate, which was washed with CH,CI, (3 x 5 mL), to give Se,N,Cl, (0.16 g, 0.48 mmol, 95% yield). Analyses: calcd.