Lanthanide(III)/Actinide(III) Differentiation in Mixed Cyclopentadienyl/Dithiolene Compounds from X-ray Diffraction and Density Functional Theory Analysis

Citations Over TimeTop 10% of 2005 papers

Abstract

Treatment of [U(Cp*)2Cl2] with Na2dddt in thf afforded the “ate” complex [U(Cp*)2Cl(dddt)Na(thf)2] (1), and the salt-free compound [U(Cp*)2(dddt)] (2) could be extracted from 1 with toluene (Cp* = η-C5Me5; dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate). Reduction of 2 with Na(Hg) or addition of Na2dddt to [U(Cp*)2Cl2Na(thf)x] in the presence of 18-crown-6 gave the first uranium(III) dithiolene compound, [Na(18-crown-6)(thf)2][U(Cp*)2(dddt)] (4). The dimeric lanthanide complexes [{Ln(Cp*)2(dddt)K(thf)2}2] (Ln = Ce (5), Nd (6)) were prepared by reaction of [Ln(Cp*)2Cl2K] with K2dddt, and in the presence of 15-crown-5, they were transformed into the cation−anion pairs [K(15-crown-5)2][Ln(Cp*)2(dddt)] (Ln = Ce (7), Nd (8)). The crystal structures of 2, 4·thf, 5−7, 7·0.5(pentane), and 8·0.5(pentane) were determined by X-ray diffraction analysis. Comparison of the structural parameters of the anions [M(Cp*)2(dddt)]- (M = U, Ce, Nd) revealed that the U−S and U−C(Cp*) distances are shorter than those expected from a purely ionic bonding model; the relatively small folding of the dddt ligand suggests that the interaction between the CC double bond and the metal center is weak, in agreement with the NMR observations in solution. The structural data obtained from molecular geometry optimizations on the complexes [M(Cp*)2(dddt)]-,0 (M = Ce, U) using relativistic density functional theory (DFT) calculations reproduce experimental trends. A detailed orbital analysis shows that the contraction of the metal−sulfur bond lengths when passing from [Ce(Cp*)2(dddt)]- to [U(Cp*)2(dddt)]- is partly related to the uranium 5f orbital−ligand mixing, which is greater than the cerium 4f orbital−ligand mixing. The comparison of the two [U(Cp*)2(dddt)]-,0 species reveals a higher ligand-to-metal donation in the case of the U(IV) complex.

Related Papers

• → Materials with layered structures: Crystal structure of Zn1.25In2.5S3Se2, a new polytype of Zn2In2S5 and the isotypic compounds Cd0.5Ga2InS5 and Hg0.8Ga1.6In1.2S5(1988)13 cited
• → Hydrothermal Synthesis and Crystal Structure of Hexafluorogallate, Na3GaF6(2017)9 cited
• → Crystal Structure of a New Modification of CoSeO3(1995)8 cited
• → The crystal structure of (Mg,Ga)₈(Ga,Ge)₂O₁₂(1992)3 cited
• → Crystal Structure of Tetraphenylarsonium Diisothiocyanatodichlorocobaltate(II)(2009)1 cited