1,2,4,5-Tetraaza-3-phospha-6-silacyclohexane. Twist conformation of an inorganic heterocycle containing hydrazine, phosphorus, and silicon. Conformational analysis in solution and x-ray structure

Abstract

Bis(1,2-dimethylhydrazido)thiophosphoric acidO-phenyl ester reacts with dichlorodiphenylsilane in the presence of triethylamine and aluminum trichloride as a catalyst in tetrahydrofuran to give 1,2,4,5-tetramethyl-3-phenoxy-6,6-diphenyl-3-thioxo-1,2,4,5-tetraaza-3-phospha-6-silacy-clohexane in about 10% yield. The six-membered ring adopts a twist conformation in solution and in the solid state. In solution a hindered twist-to-twist interconversion can be detected at low temperatures by1H-NMR. Crystals obtained from methylcyclohexane solutions are monoclinic, space groupP21/c (No. 14),a=14.983(2),b=8.267(2),c=20.019(3) A,β=103.56(2)°, x =1.26 g cm−3 forZ=4,R=0.073 for 1867 contributing reflections.