Reactivity of a Ruthenium-Carbonyl Complex in the Methanol Dehydrogenation Reaction

Finding new catalysts for the release of molecular hydrogen
from methanol is of high relevance in the context of the devel-
opment of sustainable energy carriers. Herein, we report that
the ruthenium complex Ru(salbinapht)(CO)(P i-Pr
3
) {salbinapht =
2-[({2’-[(2-hydroxybenzyl)amino]-[1,1 ’ -binaphthalen]-2-yl}imino)-
methyl]phenolato} (2) catalyzes the methanol dehydrogenation
reaction in the presence of base and water to yield H
2
, for-
mate, and carbonate. Dihydrogen is the only gas detected and
a turnover frequency up to 55 h
1
at 82 8C is reached. Complex
2 bears a carbonyl ligand that is derived from methanol, as is
demonstrated by labeling experiments. The carbony l ligand
can be treated with base to form formate (HCOO

) and hydro-
gen. The nature of the active species is further shown not to
contain a CO ligand but likely still possesses a salen-derived
ligand. During catalysis, formation of Ru(CO)
2
(H)
2
(P-iPr
3
)
2
is oc-
casionally observed, which is also an active methanol dehydro-
genation catalyst