Synthesis and Reactions of Bis (4,5‐benzo‐1,3‐dioxa‐2‐phospholano)dichlormethane

The title compound 3 was formed in the reaction of Cl 2 PCCl 2 PCl 2 ( 2 ) with catechol in the presence of triethylamine. The reaction of 3 with tetrachloro‐o‐benzoquinone (TOB), 4 , led to the σ 3 P/σ 5 P‐species 5 , and the σ 5 P/σ 5 P‐species 6a / 6b . 5 was stable only in solution, and its existence and identity are postulated on the basis of its 31 P‐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 PCP angle (123.2°) was observed in 3 . The cation of 10 is a centrosymmetric, protonated DMF dimer with OO 241.3 pm.