63672-64-0Relevant academic research and scientific papers
Molecular structure, bonding, and reaction of Mo(η5-C5H5)2 derivatives containing phosphorus ligands. Crystal structures of 5-C5H5)2H(PPh3)>I*1/2H2O and 5-C5H5)2(CH3)(PPh3)>
Azevedo, C. G.,Calhorda, M. J.,Carrondo, M. A. A. F. de C. T.,Dias, A. R.,Felix, V.,Romao, C. C.
, p. 345 - 360 (1990)
The oxidative addition reactions of 5-C5H5)2(PPh3)>, prepared by deprotonation of 5-C5H5)2H(PPh3)> with HCl, CH3I, (CH3)3SiCl and (C2H5)2S2 are described.Two of the complexes obtained have been characterized by single crystal X-ray diffraction studies, viz: 2-C5H5)2H(PPh3)>I.1/2H2O (1a) and 5-C5H5)2(CH3)(PPh3)> (3).In complex 1a, the Mo-H and Mo-P bond lengths are 1.74(8) and 2.501(4) Angstroem, and the H-Mo-P angle is 77(2) deg, while in complex 3 the Mo-C and Mo-P bond lengths are 2.269(7) and 2.526(4) Angstroem and the C-Mo-P angle is 84.1(2) deg.Molecular orbital and steric energy calculations have been carried out for some model complexes in order to throw light on their geometrical preferences and to evaluate the influence of a bulky ligand in association with a small hydride on the overall geometry of the molecule.
Photoactivation of water by Cp'2Mo and photochemical studies of Cp2MoO. Investigation of a proposed water-splitting cycle and preparation of a water-soluble molybdocene dihydride
Baxley, Gregory T.,Avey, Alfred A.,Aukett, Tim M.,Tyler, David R.
, p. 102 - 112 (2008/10/08)
Irradiation (λ > 350 nm) of Cp'2MoH2 (Cp'= η5-C5H4CH3) dissolved in 3:5 H2O-CH3CN (v/v) results in the quantitative formation of Cp'2MoO and 2 equiv. of H2. In light of this result, the photochemistry of the Cp'2MoO and Cp2MoO complexes was re-examined to determine the feasibility of using these molybdocene complexes as sensitizers in a photochemical water-splitting scheme. The metal-containing products formed by irradiation of Cp2MoO were [Cp2MoO2(MoO2)]2, {(η-C5H5)(μ-[η1:η5-C5H4])Mo}2 (C20H18Mo2) and Cp2MoPPh3 (in the presence of PPh3), but gas chromatographic and mass spectroscopic analyses showed that free O2 was not a product. Variations in the temperature, pH of the solution, and wavelength of the irradiating light did not yield any O2. Experiments showed that O2 reacted with Cp2MoO to form [Cp2MoO2(MoO2)]2. A sensitive apparatus was therefore built to remove and quantitate any O2 generated in solution (as little as 0.O2 μmol of O2) before it could react with Cp2MoO, but no O2 was detected in experiments using this apparatus. It is concluded that O2 is not produced by irradiation of Cp2MoO. Electron spin resonance experiments in the presence of α-phenyl-tert-butylnitrone, a radical spin trap, demonstrated that Cp radicals form when Cp2moO is irradiated, and it is proposed that this photoprocess may be responsible for the observed photochemistry. (C) 2000 Elsevier Science S.A.
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.
