An Actinide Complex with a Nucleophilic Allenylidene Ligand.

The reaction of [CpTh(3,3-diphenylcyclopropenyl)] (Cp = η-CH) with 1 equiv of lithium diisopropylamide (LDA) results in cyclopropenyl ring opening and formation of the thorium allenylidene complex, [Li(EtO)][CpTh(CCCPh)] ([Li(EtO)][]), in good yield. Additionally, deprotonation of [CpTh(3,3-diphenylcyclopropenyl)] with 1 equiv of LDA, in the presence of 12-crown-4 or 2.2.

Quantifying Actinide-Carbon Bond Covalency in a Uranyl-Aryl Complex Utilizing Solution C NMR Spectroscopy.

Reaction of [UOCl(THF)] with generated LiFmes (FmesH = 1,3,5-(CF)CH) in EtO resulted in the formation of the uranyl aryl complexes [Li(THF)][UO(Fmes)] ([Li(THF)][]) and [Li(EtO)(THF)][UO(Fmes)] ([Li(EtO)(THF)][]) in good to moderate yields after crystallization from hexanes and EtO, respectively. Both complexes were characterized by X-ray crystallography and NMR spectroscopy. DFT calculations reveal that the C resonance in [] exhibits a deshielding of 51 ppm from spin-orbit coupling effects originating at uranium, which indicates an appreciable covalency in the U-C bonding interaction.

Assessing the 4f Orbital Participation in the Ln-C Bonds of [Li(THF)][Ln(CCl)] (Ln = La, Ce).

The reaction of [Ln(NO)(THF)] (Ln = La, Ce) with 4 equiv of LiCCl in EtO resulted in the formation of the homoleptic lanthanide-aryl "ate" complexes [Li(THF)][La(CCl)] ([Li][]) and [Li(THF)][Ce(CCl)] ([Li][]). These complexes represent the first isolated homoleptic perchlorophenyl complexes for the lanthanides. In the solid state, both [Li][] and [Li][] exhibit octa-coordinate lanthanide centers, with four Ln-C σ-bonds and four Cl → Ln dative interactions involving the -Cl atoms of the CCl ligands.

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.

Synthesis and Characterization of Two Uranyl-Aryl "Ate" Complexes.

Reaction of [UO Cl (THF) ] with 3 equivalents of LiC Cl in Et O resulted in the formation of first uranyl aryl complex [Li(Et O) (THF)][UO (C Cl ) ] ([Li][1]) in good yields. Subsequent dissolution of [Li][1] in THF resulted in conversion into [Li(THF) ][UO (C Cl ) (THF)] ([Li][2]), also in good yields. DFT calculations reveal that the U-C bonds in [Li][1] and [Li][2] exhibit appreciable covalency.