Crystal and molecular structure of 4-methyl-4-p-nitrobenzyl-4-phosphoniatetracyclo[3.3.0.0.0]octane bromide

Abstract

Crystals of the title compound are triclinic, space group P, Z= 2, a= 6.750(3), b= 8.705(3), c= 12.961(5)Å, α= 91.60(3), β= 95.02(4), γ= 89.27(3)°. The structure was solved by the heavy-atom technique, and refined by block-diagonal least-squares methods to R 0.056 for 1 440 independent reflections. The internal angles of the phosphetan ring are 87.3, 74.8, 87.5, and 90.3°; the ring is puckered with a dihedral angle of 46.6°. The crystals were twinned, and the two twins were related by a two-fold rotation about a, which superimposed 0kl and 0kl. The twinning did not seriously limit the accuracy of the analysis.