Lutetium, thorium, and uranium complexes supported by N-containing ligands

Several f-element complexes supported by N-containing ligands are described. Synthesis and structural characterization of two dimeric halide complexes, {[tBuNON]AnCl2}2 (An = U (2.1), Th (2.2)) ([tBuNON] = [Me3CN(SiMe2)]2O2-), are reported. Reaction of 2.1 or 2.2 with LiCH2SiMe3 and C3H5MgCl resulted in [tBuNON]AnR2 (R = C3H5 or R = CH2SiMe3, An = U, Th), respectively. Reaction of 2.1 or 2.2 with Na(C5Me5) resulted in [tBuNON]An(C5Me5)Cl, which was converted to [tBuNON]An(C5Me5)(Me) (An = U (2.7), Th (2.8)) by reaction with MeMgBr. Uranium(IV) and thorium(IV) ‘ate’ complexes supported by three different diamido ether ligands are additionally discussed. Reaction of Li2[2,6-iPr2PhN(CH2CH2)]2O (Li2[DIPPNCOCN]) with UCl4 in THF generates [DIPPNCOCN]UCl3Li(THF)2 (3.1), while reaction in toluene/ether gives, [DIPPNCOCN]UCl2×½C7H8. Reaction of {[tBuNON]UCl2}2 with LiI in toluene and a minimal amount of THF resulted in [tBuNON]UI3Li(THF)2 (3.3). {[MesNON]ThCl3Li(THF)}2 was prepared by reaction of Li2[2,4,6-Me3PhN(Si(CH3)2)]2O (Li2[MesNON]) with ThCl4 in THF. The analogous reaction in toluene yielded the sterically crowded diligated, [MesNON]2Th. The reaction of 3.1 and 3.3 with LiCH2Si(CH3)3 generated stable, salt-free organoactinides. These reactions illustrate the viability of ‘ate’ complexes as useful synthetic precursors. Reaction of (C5Me5)Lu(CH2SiMe3)2(THF) (4.1) with pyridine resulted in the bis(h1-pyridine) complex, (C5Me5)Lu(NC5H5)2(CH2SiMe3)2(THF) (4.2). After standing in solution, 4.2 was converted to the h2-pyridyl complex, (C5Me5)Lu[h2-(N,C)-NC5H5](CH2SiMe3)(NC5H5) (4.4), as confirmed by X-ray crystallographic analysis. This system represents the first structurally characterized lanthanide h2-(N,C)-pyridyl complex. Isotopic labelling studies suggest that the C-H bond activation chemistry proceeds by a s-bond metathesis mechanism. Reaction of 4.1 or Lu(CH2SiMe3)3(THF)2 (4.5) with 2,2¢:6¢,2¢¢-terpyridine (tpy) or 4,4¢,4¢¢-tri-tert-butyl-2,2¢:6¢,2¢¢-terpyridine (tBu3tpy) resulted in a 1,3-migration of one of the metal-bound alkyl groups to the ortho position of the central pyridyl ring to give complexes, (C5Me5)(tpy¢)Lu(CH2SiMe3), (C5Me5)(tBu3tpy¢)Lu(CH2SiMe3), (tpy¢)Lu(CH2SiMe3)2, and (tBu3tpy¢)Lu(CH2SiMe3)2. These complexes represent the first examples of dearomatization of terpyridine and functionalization at the ortho position. Reaction of the mono(alkyl) derivative, (C5Me5)(tBu3tpy¢)Lu(CH2SiMe3), with either 4-fluoroaniline or pentafluoroaniline resulted in the amido complexes, (C5Me5)(tBu3tpy¢)Lu(NHC6H4F) and (C5Me5)(tBu3tpy¢)Lu(NHC6F5), respectively. A terminal bis(amido) complex was prepared by reaction of (tBu3tpy¢)Lu(CH2SiMe3)2 with NH2-(2,4,6-Ph3C6H2). Finally, a rare example of a room temperature stable lanthanide tris(alkyl) complex, (tBu2bpy)Lu(CH2SiMe3)3, was prepared by reaction of 4.5 with 4,4¢-di-tert-butyl-2,2¢-dipyridyl (tBu2bpy) and is ideal for future reactivity studies.