Novel scorpionate ligands devoid of C–H bonds: BpBr3 and TpBr3

Abstract

The novel ligands dihydrobis(3,4,5-tribromopyrazol-1-yl)borate, Bp^Br3, and hydrotris(3,4,5-tribromopyrazol-1-yl)borate, Tp^Br3, have been synthesized and structures of their complexes have been determined and compared with those of their almost isosteric Bp* and Tp* analogues. The structurally characterized complexes include Mo[Bp^Br3](CO)₂(η³-methallyl), Mo[Bp*](CO)₂(η³-methallyl), Mo[Tp^Br3](CO)₂(η³-methallyl), Mo[Tp*](CO)₂(η³-methallyl), Pd[Tp^Br3](η³-methallyl), Pd[Tp*](η³-methallyl), and Rh[Tp^Br3](CO)₂. The new ligands have the unique feature among scorpionates of containing no C–H bonds, thus making their organometallic derivatives more suitable for spectroscopic (IR, NMR) studies than those of other known Bp^x and Tp^x ligands.