The triphenylphosphine–benzotrifuroxan reaction. Part III. Crystal and molecular structure of a ‘light green compound’, 4-nitroso-5-tri-phenylphosphoranylideneaminobenzo[1,2-c:3,4-c′]difurazan

Abstract

The ‘light green compound’ isolated from the reaction of benzotrifuroxan with triphenylphosphine has been shown to be 4-nitroso-5-triphenylphosphoranylideneaminobenzo[1,2-c:3,4-c′]difurazan by three dimensional X-ray structure analysis. Examination of the bond-lengths suggests that it is best formulated as (I) although other resonance forms will be important. The P–N bond (1.630 Å) and nitroso-group C–N and N–O bonds. (1.369 and 1.265 Å) are respectively larger and shorter than the corresponding bond-lengths (1.39 and 1.20 Å) found in 1,4-dichloro-1′,4′dinitrosocyclohexane. The furazan rings contain CN bonds of high π bond-order (mean 1.322 Å) and the C(2)–C(3) and C(1)–C(6) bonds in the ‘benzene’ ring are similar in length (1.47 Å) to the ‘single’ bonds of a p-quinone.