Photophysical and photochemical behavior of tetrahydridobis(bis)1,2-diphenylphosphino)ethane)-molybdenum and -tungsten: optical emission and photoreduction of alkenes

Journal Article · Wed Dec 29 04:00:00 EST 1982 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00390a023· OSTI ID:6012058

Wrighton, M S; Geoffroy, G L

The complexes H/sub 4/M(DPPE)/sub 2/ and D/sub 4/M(DPPE)/sub 2/ (M = Mo, W; DPPE = bis(1,2-diphenylphosphino)ethane) exhibit emission of visible light upon photoexcitation at 77/sup 0/K in 2-methyltetrahydrofuran. The emission lifetime at 77/sup 0/K for the W species (approx. 13 ..mu..s) is shorter than for the Mo species (about 90 ..mu..s) and is independent of whether the substance is /sup 1/H or /sup 2/H. The shorter lifetime for the W species suggests an H-N/sub 2/ antibonding emissive triplet state, since the solution photochemistry at 298/sup 0/K is dominated by H/sub 2/ loss. While the lifetime of the /sup 1/H species (0.21). The data suggest that /sup 2/H diminishes nonradiative decay from the singlet excited state reached by direct absorption. This diminished nonradiative decay, yielding the emissive triplet by intersystem crossing with higher efficiency. Irradiation of H/sub 4/M(DPPE)/sub 2/ in the presence of an alkene (e.g., 1-pentene, cis-2-pentene, 3,3-dimethyl-1-pentene, cyclopentene) results a stoichiometric reduction to the alkane. Irradiation of H/sub 4/M(DPPE)/sub 2/ in the presence of alkene and 10 psi of H/sub 2/ yields photoassisted alkane formation, yielding many alkane molecules per H/sub 4/M(DPPE)/sub 2/ initially present. Photoreduction of 1-pentene or cis-2-pentene occurs without detectable isomerization to cis- and trans-2-pentene or 1- and trans--2-pentene, respectively, an unprecedented result, photoassisted alkene reactions using polyhydride precursors.

• OSTI ID: 6012058
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 104:26; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
400500 -- Photochemistry
ALKANES
ALKENES
CATALYSTS
CHEMICAL PREPARATION
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
COMPLEXES
DEUTERIUM
EMISSION
ENERGY LEVELS
EXCITED STATES
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
ISOTOPE EFFECTS
ISOTOPES
KINETICS
LIGHT NUCLEI
LOW TEMPERATURE
MOLYBDENUM COMPLEXES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHINES
PHOSPHORUS COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOEMISSION
REACTION KINETICS
REDUCTION
SECONDARY EMISSION
STABLE ISOTOPES
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
TUNGSTEN COMPLEXES
YIELDS