Deprotonation of a Seemingly Hydridic Diborane(6) To Build a B−B Bond

Abstract

Abstract Deprotonation of the doubly arylene‐bridged diborane(6) derivative 1 H 2 with (Me 3 Si) 3 CLi or (Me 3 Si) 2 NK gives the B−B σ‐bonded species M[ 1 H] in essentially quantitative yields (THF, room temperature; M=Li, K, arylene=4,4′‐di‐tert‐butyl‐2,2′‐biphenylylene). With nBuLi as the base, the yield of Li[ 1 H] drops to 20 % and the 1,1‐bis(9‐borafluorenyl)butane Li[ 2 H] is formed as a side product (30 %). In addition to the 1,1‐butanediyl fragment, the two boron atoms of Li[ 2 H] are linked by a μ‐H bridge. In the closely related molecule Li[ 3 H], the corresponding μ‐H atom can be abstracted with (Me 3 Si) 3 CLi to afford the B−B‐bonded conjugated base Li 2 [ 3 ] (THF, 150 °C; 15 %). Li[ 1 H] and Li[ 2 H] were characterized by NMR spectroscopy and X‐ray crystallography.