Synthesis and reactions of bis(4,5-benzo-1,3-dioxa-2-phospholano)dichloromethane

The title compound 3 was formed in the reaction of Cl2PCCl2PCl2 (2) with catechol in the presence of triethylamine. The reaction of 3 with tetrachloro-o-benzoquinone (TOB), 4, led to the sigma(3)P/sigma(5)P-species 5, and the sigma(5)P/sigma(5)P-species 6a/6b. 5 was stable only in solution, and its existence and identity are postulated on the basis of its P-31-NMR spectrum. The structure of 6a/6b could not be assigned unambiguously to one isomer. The reaction of 6a/6b with water yielded the phosphorate 10. The structures of 3 and 10 were determined by single crystal X-ray methods. A wide P-C-P angle (123.2 degrees) was observed in 3. The cation of 10 is a centrosymmetric, protonated DMF dimer with O ... O 241.3 pm.