Coordination Structure and Fragmentation Chemistry of the Tripositive Lanthanide-Thio-Diglycolamide Complexes

Tripositive Ln­(TMTDA)₃³⁺ complexes (Ln = La–Lu except Pm, TMTDA = tetramethyl 3-thio-diglycolamide) were observed in the gas phase by electrospray ionization of LnCl₃ and TMTDA mixtures. Collision-induced dissociation (CID) was employed to investigate their fragmentation chemistry, which revealed the influence of metal center as well as ligand on the ligated complexes. Ln­(TMTDA)₂­(TMTDA-45)³⁺ resulting from C_carbonyl–N bond cleavage of TMTDA and hydrogen transfer was the major CID product for all Ln­(TMTDA)₃³⁺ except Eu­(TMTDA)₃³⁺, which predominantly formed charge-reducing product Eu^II(TMTDA)₂²⁺ via electron transfer from TMTDA to Eu³⁺. Density functional theory calculations on the structure of La­(TMTDA)₃³⁺ and Lu­(TMTDA)₃³⁺ revealed that Ln³⁺ was coordinated by six O_carbonyl atoms from three neutral TMTDA ligands, and both complexes possessed <i>C</i>_3<i>h</i> symmetry. The S_ether atom deviating from the ligand plane was not coordinated to the metal center. On the basis of the CID results of Ln­(TMTDA)₃³⁺, Ln­(TMGA)₃³⁺, and Ln­(TMOGA)₃³⁺, the fragmentation chemistry associated with the ligand depends on the coordination mode, while the redox chemistry of these tripositive ions is related to the nature of both metal centers and diamide ligands

Matrix Infrared Spectra of Manganese and Iron Isocyanide Complexes

Mono and diisocyanide complexes of manganese and iron were prepared via the reactions of laser-ablated manganese and iron atoms with (CN)₂ in an argon matrix. Product identifications were performed based on the characteristic infrared absorptions from isotopically labeled (CN)₂ experiments as compared with computed values for both cyanides and isocyanides. Manganese atoms reacted with (CN)₂ to produce Mn­(NC)₂ upon λ > 220 nm irradiation, during which MnNC was formed mainly as a result of the photoinduced decomposition of Mn­(NC)₂. Similar reaction products FeNC and Fe­(NC)₂ were formed during the reactions of Fe and (CN)₂. All the product molecules together with the unobserved cyanide isomers were predicted to have linear geometries at the B3LYP level of theory. The cyanide complexes of manganese and iron were computed to be more stable than the isocyanide isomers with energy differences between 0.4 and 4 kcal/mol at the CCSD­(T) level. Although manganese and iron cyanide molecules are slightly more stable according to the theory, no absorption can be assigned to these isomers in the region above the isocyanides possibly due to their low infrared intensities

Formation and Structure of Gas-Phase Lanthanide(III) Cyanobenzyne Complex (η²‑4-CNC₆H₃)LnCl₂^–, Obtained via Both the Single- and Dual-Ligand Strategies

The lanthanide(III) cyanobenzyne complexes (η2-4-CNC6H3)LnCl2– (Ln = La–Lu except Eu; Pm was not examined) were generated in the gas phase using an electrospray ionization mass spectrometry coupled with collision-induced dissociation (CID) technique. For all lanthanides except Sm, Eu, and Yb, (4-CNC6H3)LnCl2– can be generated either via a single-ligand strategy through consecutive CO2 and HCl losses of (4-CNC6H4CO2)LnCl3– or via a dual-ligand strategy through successive CO2/C6H5CN or 4-CNC6H4CO2H and CO2 losses of (4-CNC6H4CO2)2LnCl2–. For Sm and Yb, although only reduction products LnCl3– were formed upon CID of (4-CNC6H4CO2)LnCl3–, (4-CNC6H3)LnCl2– were obtained via the dual-ligand strategy without the appearances of other products. CID of (4-CNC6H4CO2)EuCl3– and (4-CNC6H4CO2)2EuCl2– gave EuCl3– and the cyanophenyl complex (4-CNC6H4)EuCl2–, respectively, in both of which the +III oxidation state of Eu was reduced to +II. Density functional theory (DFT) calculations reveal that (4-CNC6H3)LnCl2– are formally described as Ln(III) cyanobenzyne complexes, (η2-4-CNC6H3)LnCl2–, with the dianionic cyanobenzyne ligand (4-CNC6H32–) coordinating to the Ln(III) centers through two Ln–C σ bonds, which is in accordance with their reactivities toward water. Benzyne and substituted benzyne complexes (XC6H3)LuCl2– (X = H, 3-CN, 4-F, 4-Cl, and 4-CH3) were also synthesized in the gas phase via the single- and dual-ligand strategies

Postsynthesis Modification of a Metallosalen-Containing Metal–Organic Framework for Selective Th(IV)/Ln(III) Separation

An uncoordinated salen-containing metal–organic framework (MOF) obtained through postsynthesis removal of Mn­(III) ions from a metallosalen-containing MOF material has been used for selective separation of Th­(IV) ion from Ln­(III) ions in methanol solutions for the first time. This material exhibited an adsorption capacity of 46.345 mg of Th/g. The separation factors (β) of Th­(IV)/La­(III), Th­(IV)/Eu­(III), and Th­(IV)/Lu­(III) were 10.7, 16.4, and 10.3, respectively