10.1021/acs.organomet.7b00423.s001 Tufan K. Mukhopadhyay Tufan K. Mukhopadhyay Chandrani Ghosh Chandrani Ghosh Marco Flores Marco Flores Thomas L. Groy Thomas L. Groy Ryan J. Trovitch Ryan J. Trovitch Hydrosilylation of Aldehydes and Formates Using a Dimeric Manganese Precatalyst American Chemical Society 2017 turnover frequency Dimeric Manganese Precatalyst imine coordination 2PEt ambient temperature propylene-bridged variant Mn catalyst Ojima mechanism Mn center κ 4 η 2 electron PDI reduction Ph PDI chelate dimer dissociation donor functionalities carboxylate hydrosilylation turnover frequencies EPR spectroscopic analysis 2017-09-13 13:18:49 Journal contribution https://acs.figshare.com/articles/journal_contribution/Hydrosilylation_of_Aldehydes_and_Formates_Using_a_Dimeric_Manganese_Precatalyst/5402014 The formally zero-valent Mn dimer [(<sup>Ph2PEt</sup>PDI)­Mn]<sub>2</sub> has been synthesized upon reducing (<sup>Ph2PEt</sup>PDI)­MnCl<sub>2</sub> with excess Na/Hg. Single crystal X-ray diffraction analysis has revealed that [(<sup>Ph2PEt</sup>PDI)­Mn]<sub>2</sub> possesses a κ<sup>4</sup>-PDI chelate about each Mn center, as well as η<sup>2</sup>-imine coordination across the dimer. The chelate metrical parameters suggest single electron PDI reduction and EPR spectroscopic analysis afforded a signal consistent with two weakly interacting <i>S</i> = <sup>1</sup>/<sub>2</sub> Mn centers. At ambient temperature in the absence of solvent, [(<sup>Ph2PEt</sup>PDI)­Mn]<sub>2</sub> has been found to catalyze the hydrosilylation of aldehydes at loadings as low as 0.005 mol % (0.01 mol % relative to Mn) with a maximum turnover frequency of 9,900 min<sup>–1</sup> (4,950 min<sup>–1</sup> per Mn). Moreover, the [(<sup>Ph2PEt</sup>PDI)­Mn]<sub>2</sub>-catalyzed dihydrosilylation of formates has been found to proceed with turnover frequencies of up to 330 min<sup>–1</sup> (165 min<sup>–1</sup> relative to Mn). These metrics are comparable to those described for the leading Mn catalyst for this transformation, the propylene-bridged variant (<sup>Ph2PPr</sup>PDI)­Mn; however, [(<sup>Ph2PEt</sup>PDI)­Mn]<sub>2</sub> is more easily inhibited by donor functionalities. Carbonyl and carboxylate hydrosilylation is believed to proceed through a modified Ojima mechanism following dimer dissociation.