Borane-Bridged Ruthenium Complex Bearing a PNP Ligand:
Synthesis and Structural Characterization
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Abstract
Reaction
of the precursor complex [RuHCl(CO)(PPh<sub>3</sub>)<sub>3</sub>]
with the PNP protioligand CbzdiphosH in toluene resulted
in the formation of two stereoisomeric hydrido complexes, [(CbzdiphosH)RuHCl(CO)]
(<b>A</b>). The addition of a strong base (KO<sup>t</sup>Bu
or LiEt<sub>3</sub>BH), on the other hand, led to the formation of
the 1,2-dehydrochlorination product [(Cbzdiphos)RuH(CO)]. The reaction
of the latter with BH<sub>3</sub>·THF at room temperature led
to the 1,2-addition of the BH<sub>3</sub> moiety to the Ru–N
function, forming a RuNBH cycle in [(CbzdiphosHBH<sub>2</sub>)RuH(CO)]
(<b>B</b>). The same borane-bridged compound was obtained when
complex <b>A</b> was treated with NaBH<sub>4</sub> in THF. The
BH<sub>2</sub> group forms a bridging unit between the carbazole-N
atom and one of the ruthenium-bound hydrides
