Homoleptic Perchlorophenyl "Ate" Complexes of Thorium(IV) and Uranium(IV).

The reaction of AnCl(DME) (An = Th, = 2; U, = 0) with 5 equiv of LiCCl in EtO resulted in the formation of homoleptic actinide-aryl "ate" complexes [Li(DME)(EtO)][Li(DME)][Th(CCl)] ([Li][]) and [Li(EtO)][U(CCl)] ([Li][]). Similarly, the reaction of AnCl(DME) (An = Th, = 2; U, = 0) with 3 equiv of LiCCl in EtO resulted in the formation of heteroleptic actinide-aryl "ate" complexes [Li(DME)(EtO)][Li(EtO)][ThCl(CCl)] ([Li][]) and [Li(EtO)][UCl(CCl)] ([Li][]). Density functional calculations show that the An-C σ-bonds are considerably more covalent for the uranium complexes vs the thorium analogues, in line with past results. Additionally, good agreement between experiment and calculations is obtained for the C NMR chemical shifts in [Li][] and [Li][]. The calculations demonstrate a deshielding by ca. 29 ppm from spin-orbit coupling effects originating at Th, which is a direct consequence of 5f orbital participation in the Th-C bonds.