Treating tri-tert-butylazadiboriridine (I) with CO in pentane gave 71% dispiro compd. II (R = Me3C throughout this abstr.). Irradn. of I with Fe(CO)5 gave 34% dioxadiazadiboranaphthalene III. Treating I with BuN3 in pentane gave 65% diazadiboretidine IV. Reaction mechanisms are discussed. The structures of II and III were detd. by x-ray chrystallog.