Stabilization of Diborane(4) Derivatives by tert‐Butyl Groups: The First Tetraalkyldiborane(4)

Boron compounds of type (alkyl)2B—B(alkyl)2, which have been sought for more than 40 years, have been independently synthesized by two research teams almost simultaneously and by the same pathway. Stepwise replacement of the methoxy groups of (1) by alkyl groups gave the tetraalkyldiboranes (4), (5) (RMe), and (6) (R=tBuCh2). Tetra-tert-butyldiborane could not be prepared, while the silylborane (7), RSiMe3, could.