C–C coupling reaction of pyridine derivatives at the dimethyl rare-earth metal cation [YMe2(THF)5]+: A DFT investigation

Applying DFT methods, the reductive elimination reaction of bis(pyridyl) rare-earth metal cation [Ln(η2-C,N-pyridyl)2(THF)3]+ (Ln = Y, La) was studied. The effect of both electron-donating and electron-withdrawing substituents in the para-position of the pyridine ring was considered. An alternative mechanism for the C–C coupling reaction between pyridine derivatives (pyridine, DMAP and 4-trifluoromethyl-pyridine) and [LnMe2(THF)5]+ (Ln = Y or La) is suggested. The reaction involves a single electron reductive C–C coupling to form of Ln(II) complexes with a bipyridine radical anion.

Graphical abstractApplying DFT methods, the reductive elimination reaction of bis(pyridyl) rare-earth metal cation [Ln(η2-C,N-pyridyl)2(THF)3]+ (Ln = Y, La) was studied. An alternative mechanism for the C–C coupling reaction between pyridine ligands is suggested. The reaction involves a single electron reductive C–C coupling to form of Ln(II) complexes with bipyridine radical anions.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► Monoelectronic reductive C-C coupling reaction is not possible for the DMAP with yttrium cations. ► Monoelectronic reductiveC-C coupling is calculated to be a possible reaction for the 4-trifluoromethyl) pyridine. ► The non reductive C-C coupling is found to be even less favourable in all cases.