Abstract

The reaction of a Ge(II) hydride compound HC{CMeArN}2GeH (Ar = 2,6-iPr2C6H3) 1 with 2,2,2-trifluoroacetophenone (CF3PhCO) is theoretically investigated with density functional theory and spin-component-scaled second-order Møller-Plesset methods. This reaction easily occurs with moderate activation barrier and considerably large exothermicity, to afford a Ge(II) alkoxide 2 through a four-membered transition state. In the transition state, the charge transfer from the Ge-H σ-bonding molecular orbital (MO) to the C═O π*-antibonding MO of CF3PhCO plays an important role. Acetone ((CH3)2CO) and benzophenone (Ph2CO) are not reactive for 1, because their π*-antibonding MOs exist at higher energy than that of CF3PhCO. Though 2 is easily formed, the catalytic hydrogenation of CF3PhCO by 1 is difficult because the reaction of 2 with a dihydrogen molecule needs a large activation energy. On the other hand, our calculations clearly show that the catalytic hydrogenation of ketone by cis-RhH(PPh3)24 easily occurs, as expected. The comparison of catalytic cycle between 1 and 4 suggests that the strong Ge-O bond of 2 is the reason of the very large activation energy for the hydrogenation by 1. To overcome this defect, we investigated various reagents and found that the catalytic cycle can be completed with the use of SiF3H. The product is silylether CF3PhCHOSiF3, which is equivalent to alcohol because it easily undergoes hydrolysis to afford CF3PhCHOH. The similar catalytic cycles are also theoretically predicted for hydrosilylations of CO2 and imine. This is the first theoretical prediction of the full catalytic cycle with a heavier main-group element compound.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.