Crystal and molecular structure of 6- t -butyl-3-cyclohexyl-3,4-dihydro-2-(2-chlorophenoxy)-2H-1,3,2-benzoxazaphosphorine-2-oxide

The structure of the title compound was determined by the Patterson method and refined to anR of 0·10 for 8065 observed reflections. The crystals are triclinicP1,a=12·408(2),b=13·157(2),c=14·479(8)?, α=74·706(8), β=88·728(9), γ=88·660(13)° withZ=4. The intensity data were collected on an Enraf-Nonius CAD-4 single crystal X-ray diffractometer. The benzoxazaphosphorine ring adopts a conformation intermediate between a half-chair and a sofa with the phosphoryl oxygen O(2) in an axial and the 2-chlorophenyl andt-butyl groups which aretrans to each other in equatorial positions. The cyclohexyl ring adopts a chair conformation with the nitrogen atomN(5) in an equatorial position. In one conformation of the molecule (I) thet-butyl group atoms and one of the carbon atoms, C(24) in the cyclohexyl ring are disordered. In the other conformation (molecule II) the 2-chlorophenyl ring adopts a conformation midway between a half-chair and a sofa. The molecular packing involves mainly van der Waals contacts.