Alvarez, Celedonio M. Alvarez, M. Angeles Alonso, María García, M. Esther Rueda, M. Teresa Ruiz, Miguel A. Herson, Patrick Trapping of Hemiquinone Radicals at Mo and P Sites by Phosphide-Bridged Dimolybdenum Species:  Chemistry of Complexes [Mo<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>(OC<sub>6</sub>H<sub>4</sub>OH)(μ-PR<sub>2</sub>)(CO)<sub>4</sub>] and [Mo<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>{μ-PR(OC<sub>6</sub>H<sub>4</sub>OH)}(CO)<sub>4</sub>]<sup>-</sup> (R = Cy, Ph) The phosphide-bridged dimolybdenum complexes (H-DBU)[Mo<sub>2</sub>Cp<sub>2</sub>(μ-PR<sub>2</sub>)(CO)<sub>4</sub>] (R= Cy, Ph; DBU = 1,8-diazabicyclo[5.4.0.]undec-7-ene) react with <i>p</i>-benzoquinone to give the hemiquinone complexes [Mo<sub>2</sub>Cp<sub>2</sub>(OC<sub>6</sub>H<sub>4</sub>OH)(μ-PR<sub>2</sub>)(CO)<sub>4</sub>]. The latter experience facile homolytic cleavage of the corresponding Mo−O bonds and react readily at room temperature with HSPh or S<sub>2</sub>Ph<sub>2</sub> to give the thiolate complexes [Mo<sub>2</sub>Cp<sub>2</sub>(μ-PCy<sub>2</sub>)(μ-SPh)(CO)<sub>4</sub>] or [Mo<sub>2</sub>Cp<sub>2</sub>(μ-PR<sub>2</sub>)(μ-SPh)(CO)<sub>2</sub>]. In contrast, PRH-bridged substrates experience overall insertion of quinone into the P−H bond to give the anionic compounds (H-DBU)[Mo<sub>2</sub>Cp<sub>2</sub>{μ-PR(OC<sub>6</sub>H<sub>4</sub>OH)}(CO)<sub>4</sub>], which upon acidification yield the corresponding neutral hydrides. The cyclohexyl anion experiences rapid nucleophilic displacement of the hemiquinone group by different anions ER<sup>-</sup> (ER = OH, OMe, OC<sub>4</sub>H<sub>5</sub>, OPh, SPh) to give novel anionic compounds (H-DBU)[Mo<sub>2</sub>Cp<sub>2</sub>{μ-PCy(ER)}(CO)<sub>4</sub>], which upon acidification yield the corresponding neutral hydrides. The structure of four of these hydride complexes [PPh(OC<sub>6</sub>H<sub>4</sub>OH), PCy(OH), PCy(OMe), and PCy(OPh) bridges] was determined by X-ray diffraction methods and confirmed the presence of cis and trans isomers in several of these complexes. In addition, it was found that the hydroxyphosphide anion [Mo<sub>2</sub>Cp<sub>2</sub>{μ-PCy(OH)}(CO)<sub>4</sub>]<sup>-</sup> displays in solution an unprecedented tautomeric equilibrium with its hydride-oxophosphinidene isomer [Mo<sub>2</sub>Cp<sub>2</sub>(μ-H){μ-PCy(O)}(CO)<sub>4</sub>]<sup>-</sup>. OH;DBU;ER;cyclohexyl anion experiences;OC 4H OPh;complex;Mo 2Cp;Mo 2Cp displays 2006-11-13
    https://acs.figshare.com/articles/dataset/Trapping_of_Hemiquinone_Radicals_at_Mo_and_P_Sites_by_Phosphide_Bridged_Dimolybdenum_Species_Chemistry_of_Complexes_Mo_sub_2_sub_sup_5_sup_C_sub_5_sub_H_sub_5_sub_sub_2_sub_OC_sub_6_sub_H_sub_4_sub_OH_PR_sub_2_sub_CO_sub_4_sub_and_Mo_sub_2_sub_sup_5_sup_C/3048487
10.1021/ic061344e.s002