The effects of light lanthanoid elements (La, Ce, Nd) on (Ar)CF–Ln coordination and C–F activation in N,N-dialkyl-N′-2,3,5,6-tetrafluorophenylethane-1,2-diaminate complexes

Abstract

A new class of homoleptic organoamido rare earth complexes [Ln(L^Me or L^Et)₃] (Ln = La, Ce, Nd; L^Me/Et = p-HC₆F₄N(CH₂)₂NMe₂/Et₂) exhibiting (Ar)CF–Ln interactions has been isolated from redox–transmetallation/protolysis (RTP) reactions between the free metals, Hg(C₆F₅)₂ and L^Me/EtH in tetrahydrofuran, together with low yields of [Ln(L^Me)₂F]₃ (Ln = La, Ce) or [Nd(L^Et)₂F]₂ species, resulting from C–F activation reactions. The structures of the homoleptic complexes have eight-coordinate Ln metals with two tridentate (N,N′,F) amide ligands including (Ar)CF–Ln bonds and either a bidentate (N,F) ligand (Ln = La, Ce, Nd; L^Et) or a bidentate (N,N′) ligand (Ln = Nd; L^Me), in an unusual case of linkage variation. All (Ar)CF–Ln bond lengths are shorter than or similar to the corresponding Ln–NMe₂/Et₂ bond lengths. In [Ln(L^Me)₂F]₃ (Ln = La, Ce) complexes, there is a six-membered ring framework with alternating F and Ln atoms and the metal atoms are eight-coordinate with two tridentate (N,N′,F) L^Me ligands, whilst [Nd(L^Et)₂F]₂ is a fluoride-bridged dimer.