1,3‐Di‐tert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazaborole (4a) and 1,3‐bis(2,6‐dimethylphenyl)‐2,3‐dihydro‐1H‐1,3,2‐diazaborole (4b) were formed by the reaction of the corresponding 2‐bromo or 2‐iodo derivatives 1a and 2b with LiAlH4. Treatment of 1a with n‐butyllithium afforded 2‐n‐butyl‐1,3‐di‐tert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazaborole (5a), whereas 1,3‐di‐tert‐butyl‐2‐cyano‐2,3‐dihydro‐1H‐1,3,2‐diazaborole (3a) was converted into the 2‐tert‐butyl derivative 6a or the 2‐ethynyl‐1,3,2‐diazaborole 7a by means of tert‐butyllithium or by the ethylenediamine adduct of lithium acetylide. Similarly, 1,3‐di‐tert‐butyl‐2‐trimethylstannyl‐2,3‐dihydro‐1H‐1,3,2‐diazaborole (8a) and 1,3‐bis(2,6‐dimethylphenyl)‐2‐trimethylstannyl‐2,3‐dihydro‐1H‐1,3,2‐diazaborole (8b) were accessible from 1a or 2b and trimethylstannyllithium. In the complex 9a the compound 3a serves as an η1 ligand towards the [Cr(CO)5] unit via the cyano group. These novel compounds were characterized by 1H‐, 11B‐, 13C‐, and 119Sn‐NMR spectroscopy, as well as by X‐ray structure analyses of 4b, 8a, and 9a.