Reactions of Tri‐ tert ‐butylazadiboriridine NB 2 R 3 with Carbonyl and Similar Species

The carbonyl group of X(R')CO is added to the B—B bond of the three‐membered ring compound NB 2 R 3 ( 1 ; R = t Bu) to give the five‐membered rings [—BR—NR—BR—X(Rapos;)C—O—] ( 2a — d ; Rapos;/X = t Bu/H, Ph/Ph, H/OMe, H/NMe 2 ). The tetraazoniatetraboratatricyclo[6.2.0.0 3, 6 ]deca‐2, 4, 7, 9‐tetraenes N 4 B 4 C 2 R 6 Rapos; 2 ( 4a , b ; Rapos; = Me, Et), known products from the reaction of 1 with isonitriles CNRapos;, undergo a rearrangement to give the corresponding deca‐1, 4, 6, 9‐tetraenes 6a , b by the migration of two t Bu groups from boron to carbon on photolysis; the structure of 6a is confirmed by X‐ray analysis. The reaction of CO, generated from carbonylmetal complexes (photolytically from [Cr(CO) 6 ] or [Cp 2 Fe 2 (CO) 4 ]; thermally from [Fe 2 (CO) 9 ] or [Co 2 (CO) 8 ]), with 1 gives the 3, 7‐dioxonia‐1, 5‐diazonia‐2, 4, 6, 8‐tetraboratanaphtalene O 2 N 2 C 2 B 4 R 6 ( 7 ), as has been known from the reaction of [Fe(CO) 5 ] and 1 . The product 7 is also obtained from the isomeric dispiro compound 5 , the known product from the reaction of 1 with gaseous CO at —78 °C, by standing in solution at room temperature. Surprisingly, the reaction of 1 with CO from the photolysis of [CpMn(CO) 3 ] gives a naphthalene‐type isomer of 7 , the 1, 5‐dioxonia‐3, 7‐diazonia species 8 , the crystal structure of which is reported.