Monomeric Aldimino‐diorganoboranes and Aspects of Their Chemistry

The hydroboration of benzo‐, tolu‐, p 1‐methoxybenzo‐, or pivalonitriles with bis(9‐borabicyclo[3.3.1]nonane) ( 9H‐9‐BBN) 2 affords the corresponding 9‐aldimino‐9‐borabicyclo[3.3.1]1‐nonanes ( 1a — d ) in about 80% yields. Compounds 1a and 1d readily react with an excess of ( 9H‐9‐BBN) 2 to form the 1:1 adducts 2a or 2d , respectively, containing a NB 2 H four‐membered ring (X‐ray structure of 2a ). The adducts 2 are thermally rather stable. Compound 2a is converted to benzylbis(1,5‐cyclooctanediylboryl)amine ( 3a ) only after 48 h at reflux in mesitylene. Compounds 1a — d are stable towards strong N‐bases. Compound 1d reacts with Et 2 O · BF 3 to form 9‐fluoro‐9‐borabicyclo[3.3.1]nonane ( 4 ) and the 1:1 cyclic adduct ( 5d ) of (2,2‐dimethylpropylideneamino)difluoroborane ( 6d ) and 1d .