Direct Observation of a Bent Carbonyl Ligand in a 19-Electron Transition Metal Complex

作者：Lomont Justin P; Nguyen Son C; Harris Charles B^*

来源：Journal of Physical Chemistry A, 2013, 117(11): 2317-2324.

DOI：10.1021/jp311732t

The photochemistry of [CpRu(CO)(2)](2) in P(OMe)(3)/CH2Cl2 solution has been studied using picosecond time-resolved infrared (TRIR) spectroscopy. Photolysis at 400 nm leads to the formation of 17-electron CpRu(CO)(2)(center dot) radicals, which react on the picosecond time scale to form 19-electron CpRu(CO)(2)P(OMe)(3)(center dot) adducts. The TRIR spectra of this adduct display an unusually low CO stretching frequency for the antisymmetric CO stretching mode, suggesting that one carbonyl ligand adopts a bent configuration to avoid a 19-electron count at the metal center. This spectral assignment is supported by analogous experiments on [CpFe(CO)(2)](2) in the same solvent, combined with DFT studies on the structures of the 19-electron adducts. The DFT results predict a bent CO ligand in CpRu(CO)(2)P(OMe)(3)(center dot), whereas approximately linear Fe-C-O bond angles are predicted for CpFe(CO)(2)P(OMe)(3)(center dot). The observation of a bent CO ligand in the 19-electron ruthenium adduct is a surprising result, and it provides new insight into the solution-phase behavior of 19-electron complexes. TRIR spectra were also collected for [CpRu(CO)(2)](2) in neat CH2Cl2, and it is interesting to note that no singly bridged [CpRu(CO)](2)(mu-CO) photoproduct was observed to form following 400- or 267-nm excitation, despite previous observations of this species on longer time scales.

• 出版日期2013-3-21