PMID- 16144403
OWN - NLM
STAT- MEDLINE
DCOM- 20060203
LR  - 20131121
IS  - 0002-7863 (Print)
IS  - 0002-7863 (Linking)
VI  - 127
IP  - 36
DP  - 2005 Sep 14
TI  - 19-electron intermediates and cage-effects in the photochemical 
      disproportionation of [CpW(CO)3]2 with Lewis bases.
PG  - 12555-65
AB  - The role of 19-electron intermediates in the photochemical disproportionation of 
      [CpW(CO)3]2 (Cp = C5H5) with Lewis bases (PR3; R = OMe, Bu, Ph) is investigated 
      on the ultrafast time scale using femtosecond VIS-pump, IR-probe spectroscopy. 
      Formation of a 19-electron (19e) species CpW(CO)3PR3*by coordination of PR3 with 
      photogenerated 17-electron (17e) radicals CpW(CO)3* is directly observed, and 
      equilibrium is established between the 17e radicals and the 19e intermediates 
      favoring 19e intermediates in the order: Bu > OMe >> Ph. Steric effects dominate 
      the 17e/19e equilibrium when the cone-angle of the Lewis base exceeds a certain 
      limiting value (between 132 degrees and 145 degrees ), but below this value 
      electronic properties of the Lewis base control the 17e/19e dynamics. 
      Disproportionation occurs in less than 200 picoseconds by electron transfer 
      between a solvent caged 17e radical and 19e, highly reducing species. The rate 
      and extent of ultrafast disproportionation depends on both the identity and 
      concentration of the Lewis base. In low concentrations of PR3 (typically 1-2 M or 
      less) or with Lewis bases whose equilibrium heavily favors 17e radicals (e.g., 
      PPh3), disproportionation is rate-limited by breakdown of the solvent cage. 
      Density functional theory calculations on vibrational frequencies and charge 
      distributions of the various complexes support the experimental results.
FAU - Cahoon, James F
AU  - Cahoon JF
AD  - Department of Chemistry, University of California, Berkeley, California 94720, 
      USA.
FAU - Kling, Matthias F
AU  - Kling MF
FAU - Schmatz, Stefan
AU  - Schmatz S
FAU - Harris, Charles B
AU  - Harris CB
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - United States
TA  - J Am Chem Soc
JT  - Journal of the American Chemical Society
JID - 7503056
RN  - 0 (Organometallic Compounds)
RN  - 0 (Organophosphorus Compounds)
RN  - V9306CXO6G (Tungsten)
SB  - IM
MH  - Electrons
MH  - Molecular Conformation
MH  - Organometallic Compounds/*chemical synthesis/chemistry/radiation effects
MH  - Organophosphorus Compounds/*chemistry
MH  - Photochemistry
MH  - Time Factors
MH  - Tungsten/*chemistry
EDAT- 2005/09/08 09:00
MHDA- 2006/02/04 09:00
CRDT- 2005/09/08 09:00
PHST- 2005/09/08 09:00 [pubmed]
PHST- 2006/02/04 09:00 [medline]
PHST- 2005/09/08 09:00 [entrez]
AID - 10.1021/ja052221g [doi]
PST - ppublish
SO  - J Am Chem Soc. 2005 Sep 14;127(36):12555-65. doi: 10.1021/ja052221g.