78356-94-2Relevant academic research and scientific papers
Descriptive photochemistry and electronic structure of the Cp2MoO and (MeCp)2MoO complexes (Cp = η5-C5H5; MeCp = η5-CH3C5H4)
Silavwe, Ned D.,Bruce, Mitchell R. M.,Philbin, Cecelia E.,Tyler, David R.
, p. 4669 - 4676 (2008/10/08)
The photochemistry of the Cp2MOo and (MeCp)2MoO complexes was studied because these complexes are potential photochemically activated oxygenating agents. Irradiation of these complexes in deoxygenated solutions initially forms Cp2Mo (or (MeCp)2Mo) and O2: 2Cp2MoO →hν 2Cp2Mo + O2. The products that subsequently form arise from the reaction of the photogenerated O2 with Cp2MoO and Cp2Mo. Thus, Cp2MoO reacted with O2 to give [Cp2Mo(MoO4)]2. Cp2Mo dimerized to give C20H18Mo2, and this species subsequently reacted with O2 to give an unidentified oxide (complex A). In the presence of ligands, Cp2Mo was captured to give Cp2MoL-type products (L = CO, PR3, olefin). In the presence of SEt2, CpMo(H)Et formed. In no case, except PPh3, was oxygen atom transfer to any substrate (olefin, phosphine, amine, sulfide) observed. In the case of PPh3, OPPh3 probably formed by reaction of O2 with PPh3. Photochemical oxygen atom transfer from Cp2MoO to the substrates failed because Cp2Mo is a better oxygen atom acceptor than the substrates. The electronic structure of the Cp2MoO complex was investigated by using the self-consistent-field-Xα-scattered-wave (SCF-Xα-SW) molecular orbital method. The calculation showed that the Mo-O bond is best described as being intermediate between a double and a triple bond. This conclusion is consistent with X-ray diffraction and infrared spectroscopic results [d(Mo-O) = 1.721 (2) A?; ν(Mo-O) = 827 cm-1 for (MeCp)2MoO]. The calculation predicts a d-d excited state at lowest energy, with O → Mo and Cp → Mo charge-transfer states at higher energy. The photochemistry was independent of wavelength; the lowest energy d-d excited state (13a1 → 8b1; 1A1 → 1B1) is apparently the reacting state.
