Pyrazole‐Organoboranes, VI. Monomeric and Dimeric 9‐Pyrazolyl‐9‐borabicyclo[3.3.1]nonanes

Bis(9H‐9‐borabicyclo[3.3.1]nonane) (9H‐9‐BBN)2 reacts with pyrazole (Pz) and its 4‐bromo, 3‐methyl, 3‐phenyl, 3,5‐dimethyl, 3‐methyl‐5‐phenyl, 3,5‐diphenyl, 3,5‐di‐ert‐butyl, 3,5‐diadamantyl, 3,5‐di‐tert‐butyl‐4‐methyl, and 3,5‐di‐tert‐butyl‐4‐ethyl derivatives [brPz, mPz, pPz, m2Pz, mpPz, p2Pz, (tb)2Pz, (ad)2Pz, (tb)2mPz, and (tb)2mPz, and (tb)2ePz, respectively] to give the 9‐pyrazolyl‐9‐borabicyclo[3.3.1]nonanes with the dimeric structure (1)2–(3)2 (X‐ray, NMR, and MS analysis), and 4–11 with monomeric structures (X‐ray, NMR, MS).