Adducts of the Parent Boraphosphaketene H2BPCO and their Decarbonylative Insertion Chemistry

The first examples of Lewis base adducts of the parent boraphosphaketene (H 2 B-PCO) and their cyclodimers are prepared. One of these adducts is shown to undergo mild decarbonylation and phosphinidene insertion into a B-C bond of a borole, forming very rare examples of 1,2-phosphaborinines, B/P isosteres of benzene. The strong donor properties of these 1,2-phosphaborinines are confirmed by the synthesis of their π complexes with the Group 6 metals.