6-(2,4-Dichloro­phen­oxy)­dibenzo­[d,f]­[1,3,2]­dioxaphosphepine-6-sulfide

In the title compound, C₁₈H₁₁Cl₂O₃PS, the seven-membered phosphepine ring exhibits a distorted-boat conformation, with the phosphor­yl sulfide group axial and the dichloro­phen­oxy group equatorial. Fusion of the phosphepine ring to the biphen­yl system causes strain, as evidenced by both widening and compression of the endocyclic angles in the heterocyclic ring. The P=S bond length is 1.8939 (12) Å and the planar dichloro­phen­yl ring is oriented at an angle of 28.70 (6)° to the phosphepine ring.