Details

Autor(en) / Beteiligte

• Li, Tongyu
• Heng, Yi
• Wang, Dongwei
• Hou, Guohua
• Zi, Guofu
• Ding, Wanjian
• Walter, Marc D.

Titel

Uranium versus Thorium: A Case Study on a Base-Free Terminal Uranium Imido Metallocene

Ist Teil von

• Inorganic chemistry, 2024-05, Vol.63 (21), p.9487-9510

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2024

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The structure of and bonding in two base-free terminal actinide imido metallocenes, [η5-1,2,4-(Me3C)3C5H2]2AnN­(p-tolyl) (An = U (1), Th (1′)) are compared and connected to their individual reactivity. While structurally rather similar, the U­(IV) derivative 1 is slightly more sterically crowded. Furthermore, density functional theory (DFT) studies imply that the 5f orbital contribution to the bonding within the individual actinide imido AnN­(p-tolyl) moieties is significantly larger for 1 than for 1′, which makes the bonds between the [η5-1,2,4-(Me3C)3C5H2]2U2+ and [(p-tolyl)­N]2– fragments more covalent. Therefore, steric and electronic factors impact the reactivity of these imido complexes. For example, complex 1 is inert toward internal alkynes, but it readily forms Lewis base adducts [η5-1,2,4-(Me3C)3C5H2]2UN­(p-tolyl)­(L) (L = OPMe3 (6), dmap (9), PhCN (14), and 2,6-Me2PhNC (17)) with Me3PO, 4-dimethylaminopyridine (dmap), nitrile, PhCN, or isonitrile 2,6-Me2PhNC. It may also react as a nucleophile or undergo a [2 + 2] cycloaddition with CS2, isothiocyanates, thio-ketones, ketones, lactides, and acyl nitriles, forming the four- or five-membered metallaheteroacycles, terminal sulfido, or oxido complexes, and cyanide amidate complexes, respectively. In contrast, after the addition of aldehyde p-tolylCHO, the tetranuclear complex [η5-1,2,4-(Me3C)3C5H2]4[OCH­(p-tolyl)­CH­(p-tolyl)­O]2U4O4 (10) is isolated. However, while 1 is unreactive toward dicyclohexylcarbodiimide (DCC), an equilibrium exists in benzene solution between N,N′-diisopropylcarbodiimide (DIC), 1, and the four-membered metallaheterocycle [η5-1,2,4-(Me3C)3C5H2]2U­[N­(p-tolyl)­C­(N i Pr)­N­( i Pr)] (12). Furthermore, 1 may also engage in single- and two-electron transfer processes. It is singly oxidized by Ph3CN3, CuI, Ph2S2, and Ph2Se2, yielding the uranium­(V) imido complexes [η5-1,2,4-(Me3C)3C5H2]2UN­(p-tolyl)­(X) (X = N3 (20), I (22), PhS (23), and PhSe (24)), or is doubly oxidized by organic azides (RN3) and 9-diazofluorene, forming the uranium­(VI) bis-imido metallocenes [η5-1,2,4-(Me3C)3C5H2]2UN­(p-tolyl)­(=NR) (R = p-tolyl (18), mesityl (19)) and [η5-1,2,4-(Me3C)3C5H2]2U=N­(p-tolyl)­[=NN=(9-C13H8)] (21), respectively.