Facile Insertion of CO₂ into Tetra- and Pentamethylcyclopentadienyl Lanthanide Moieties To Form (C₅Me₄RCO₂)^- Carboxylate Ligands (R = H, Me)

Abstract

Recent efforts to extend the reduction chemistry of LnZ 3 /M and LnZ 2 Z′/M (Ln ) lanthanide; Z ) C 5 Me 5 , C 5 Me 4 H; Z′ ) BPh 4 , Cl; M ) alkali metal) to substrates beyond N 2 have identified unexpectedly facile insertion of CO 2 into lanthanide cyclopentadienyl linkages to make carboxylate ligands. The insertion was initially identified in [(C 5 Me 4 H)La(THF)] 3 (µ-η 1 :η 1 -O 2 CC 5 Me 4 H) 3 (µ 3 -η 2 :η 2 :η 2 -CO 3 )(µ 3 -Cl), 1, a product of a (C 5 Me 4 H) 3 La/Na/CO 2 reaction in the presence of chloride. In this case, both insertion and reduction of CO 2 to carbonate was observed. A [(C 5 Me 5 ) 2 La][(µ-Ph) 2 BPh 2 ]/KC 8 /CO 2 reaction also provided a CO 2 insertion product, [(C 5 Me 5 )La(µ-η 1 :η 1 -O 2 CC 5 Me 5 )(µ-η 1 :η 2 -O 2 CC 5 Me 5 )] 2 , 2, but in this case a CO 2 reduction product was not identified. CO 2 insertion also occurs in the absence of an alkali metal. Hence, the (C 5 -Me 4 H) 3 Ln complexes (Ln ) La, Nd, Sm, Gd) react with CO 2 to form mixtures of tetramethylcyclopentadienyl carboxylate products. In the La complex, single crystals of {[(C 5 Me 4 H) 2 La](µ-η 1 :η 1 -O 2 CC 5 -Me 4 H)} 2 , 3, could be isolated and structurally characterized. Crystallographic characterization of a rare example of a tetramethylcyclopentadienyl lanthanide ate salt, [(µ-C 5 Me 4 H)(C 5 Me 4 H)LaCl(µ-Cl)K(18crown-6)] n , 4, was also obtained as part of this study, and it was found to have a chain structure in the solid state involving bridging methyl groups as well as bridging chloride ligands.

Density Functional Theory and X-ray Analysis of the Structural Variability in η5,η5,η1-Tris(ring) Rare Earth/Actinide Tetramethylpyrrolyl Complexes, (C5Me5)2M(NC4Me4)

“…1,2 Hence, as shown in Scheme 1, the (C 5 Me 5 ) 3 M compounds can ring-open tetrahydrofuran (THF), 1 polymerize ethylene, 1 undergo hydrogenolysis, 1 and engage in CO 2 2 and CO 3 insertion chemistry.…”

Utilization of Methacrylates and Polymer Matrices for the Synthesis of Ion Specific Resins

“…The milestone we expect to achieve in the first year include the synthesis and characterization of various metal methacrylate complexes, which will add to our knowledge of lanthanide carboxylate chemistry, an area for which discoveries and incites are still being made. 11,12 Additionally, the ability of heterometallic combinations and the synthetic requirements will not only add to the basic understanding of mixed-metal chemistry, but also provide insight and possible selective complexation of relevant metals for separations and processing.…”

Actinyl-Modified g-C3N4 as CO2 Activation Materials for Chemical Conversion and Environmental Remedy via an Artificial Photosynthetic Route

“…However, despite the availability of an enormous amount of literature on the accumulation of transition and main-group metals into CN , in which the resultant materials showed excellent reactivities for CO 2 activation, actinides have never been investigated for their modification. Moreover, the low - and mid -valent uranium and thorium in complexation with nitrogen-rich ligands have already proved to be appealing in the context. − Low -valent species, due to their highly reductive nature, have received special attraction in this regard. ,,− Among these, uranium has been a subject of tremendous interest and has been investigated with other ligand systems in almost all low -, mid -, and high -valent (though the last is rare) oxidation states, for the CO 2 RR, the HER, the nitrogen reduction reaction (NRR), coupling reactions, hydroelementation, ring-opening polymerization, alkene polymerization, and reduction of hydrazines and azides and carbamate formation. ,− The trans uranium elements (Np and Pu), although hardly investigated for CO 2 activation, may also show similar kinds of activities. ,, …”