Mechanistic Insights into Concerted C–C Reductive Elimination from Homoleptic Uranium Alkyls

Abstract

A mechanistic study was carried out to probe concerted C–C reductive elimination from homoleptic uranium(IV) alkyls. The para-chloro uranium(IV) tetrabenzyl derivative, U(CH2–p-ClC6H4)4 (2-p-Cl), was synthesized by treating UCl4 with 4 equivalents of KCH2–p-Cl-Ph (1-p-Cl) at −108 °C, adding a new member to the previously reported family of uranium alkyl complexes U(CH2C6H5)4 (2-Bn), U(CH2–p-iPrC6H4)4 (2-p-iPr), U(CH2–ptBu-C6H4)4 (2-p-tBu), U(CH2–o-OMeC6H4)4 (2-o-OMe), and U(CH2–m-OMeC6H4)4 (2-m-OMe). Each member of this family readily reacts with the redox-active α-diimine ligand, MesDABMe (MesDABMe = [MesN═C(Me)C(Me)═NMes]; Mes = 2,4,6-trimethylphenyl), to afford the products from C–C reductive elimination, namely, (MesDABMe)U(CH2Ph′)2 and Ph′CH2CH2Ph′ (Ph′ = p-iPrC6H4, p-tBuC6H4, m-OMeC6H4, p-ClC6H4). Room-temperature magnetic-susceptibility values, obtained via SQUID magnetometry, show a correlation with an increase in the magnetic moment as the electron-withdrawing character of the substituent increas...