Metal and Organometal Complexes of Oxy and Thiophosphorus Acids. Part VI. O-Alkyl-O-boryl Phosphonates

2-(O-Alkyl phosphonato)-1,3,2-dioxaborinanes, Activated OCH2CH2CH2OBOP(O)(H)OEt, Activated OCHMeCH2CH2OBOP(O)(H)OR (R = Et, Pr(n), Bu(n)) and Activated OCH2CMe2CH2OBOP(O)(H)OR (R = Pr(n), Bu(n)), obtained by the reaction of 2-chloro-1,3,2-dioxaborinanes with sodium salts of O-alkyl phosphonic acids, are colourless, hydrolysable, monomeric, volatile liquids. These have been characterised by molecular weight, IR and multinuclear (H-1, C-13, B-11 and P-31) NMR spectral data which suggest the presence of monodentate phosphonato moieties and 3-coordinate boron atoms. The 2-chloro-1,3,2-dioxaborinanes have been prepared by a new route from the corresponding oxybis (1,3,2-dioxaborinanes) and PCl5.