A photochemical synthesis of
[CpOs(CH3CN)3]+ is
reported (Cp = η5-cyclopentadienyl). Photolysis of
[CpOs(Bz)]+ (Bz = η6-benzene) in acetonitrile
solution gives
[CpOs(CH3CN)3]+, but only
30% conversion is achieved
before significant photochemically induced decomposition of
[CpOs(CH3CN)3]+
occurs. Photolysis of acetonitrile
solutions of [CpOs(Bz)]+ that contain biphenyl
eliminates this side reaction and allows the high-yield
preparation
of [CpOs(CH3CN)3]+.
Quantum yields for the photodearylation reaction are identical in
the presence or absence
of biphenyl, suggesting that biphenyl acts as a passive filter, slowing
the photochemical decomposition of [CpOs(CH3CN)3]+.
[CpOs(CH3CN)3]+
reacts with arenes, CO, and polypyrazolylborate ligands, providing a
high-yield route to CpOsL3 compounds under mild conditions.
Compounds that were synthesized and fully
characterized
include [CpOs(η6-anthracene)]PF6,
[CpOs(η6-rubrene)]PF6,
CpOs(BPz4) (BPz4
- =
tetrakis(1-pyrazolyl)borate),
CpOs(HBPz3) (HBPz3
- =
hydrotris(1-pyrazolyl)borate),
[CpOs(CH3CN)2CO]PF6,
and CpOs(CO)2Br. 1H NMR
evidence for an additional species
([(CpOs)(CpOs(CH3CN))(μ-η6,η4-anth)]2+)
that contains an η6 and an η4
CpOs+
group is presented. Intriguing differences between the reactivity
of [CpOs(CH3CN)3]+
and
[CpRu(CH3CN)3]+
with rubrene are observed, with the osmium complex showing a remarkable
kinetic preference for the naphthacene
backbone relative to the pendant phenyl rings.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.