THE PREPARATION AND X-RAY STRUCTURE OF [P(C2H5)(4)](-3](-) AND THE ATTEMPTED PREPARATION OF [PH4](+)[N-3](-)()[N)

Tetraethylphosphonium azide, [P(C2H5)(4)](+)[N-3](-), was prepared fro m tetraethyl phosphonium bromide and silver azide. Single crystals of [P(C2H5)(4)](+)[N-3](-) were Pro tvn from dichloromethane/THF (10:1) s olution. The structure was determined by single-crystal X-ray diffract ion analysis. [P(C2H5)(4)](+)[N-3](-) crystallizes in the monoclinic s pace group C 2/c with Z = 4 and unit cell dimensions a = 12.961(6), b = 6.835(3), c = 12.378(6) Angstrom, and beta = 100.57(4)degrees. The a ttempted preparation of phosphonium azide [PH4](+)[N-3](-) from phosph onium iodide and silver azide lead instead to the formation of PH3 and HN3. The instability of [PH4](+)[N-3]- with respect to PH3 and HN3 is in accord with thermodynamic considerations according to which the re action PH3(g) and HN3(g) to yield [PH4](+)[N-3](-) is thermodynamicall y unfavorable. (Non SI units employed: kcal approximate to 4.184 J, An gstrom = 10(-10)m.) (C) 1998 John Wiley & Sons, Inc.