Bonding Trends in Tetravalent Th–Pu Monosalen Complexes

Abstract

The synthesis of three complex series of the form [AnCl2(salen)(Pyx)2] (H2salen=N,N′‐bis(salicylidene)ethylenediamine; Pyx=pyridine, 4‐methylpyridine, 3,5‐dimethylpyridine) with tetravalent early actinides (An=Th, U, Np, Pu) is reported with the goal to elucidate the affinity of these heavy elements for small neutral N‐donor molecules. Structure determination by single‐crystal XRD and characterization of bulk powders with infrared spectroscopy reveals isostructurality within each respective series and the same complex conformation in all reported structures. Although the trend of interatomic distances for An−Cl and An−N (imine nitrogen of salen or pyridyl nitrogen of Pyx) was found to reflect an ionic behavior, the trend of the An−O distances can only be described with additional covalent interactions for all elements heavier than thorium. All experimental results are supported by quantum chemical calculations, which confirm the mostly ionic character in the An−N and An−Cl bonds, as well as the highest degree of covalency of the An−O bonds. Structurally, the calculations indicate just minor electronic or steric effects of the additional Pyx substituents on the complex properties.

Comprehensive Bonding Analysis of Tetravalent f-Element Complexes of the Type [M(salen)2]

“…All synthetic work in this study was performed in an oxygen- and water-free glovebox filled with nitrogen gas. The synthesis (Scheme ) and solid-state characterization of bis­(salen) complexes were described previously . Single crystals of [M­(salen) 2 ] were grown by layering a solution of the complex in tetrahydrofuran (THF) with pentane.…”

“…The synthesis (Scheme 1) and solid-state characterization of bis(salen) complexes were described previously. 44 Single crystals of [M(salen) 2 ] were grown by layering a solution of the complex in tetrahydrofuran (THF) with pentane.…”

Taming salophen in rare earth metallocene chemistry

“…Multidentate Schiff base ligands, such as salen-type ligands, where salen = N,N′-bis(salicylidene)-ethylenediamine, form stable complexes with transition metals, 1 lanthanides, 2 and actinides, 3 comprising various metal oxidation states and featuring compounds of differing nuclearity. In particular, the tert-butyl-functionalized salophen ligand, N,N′-o-phenylene-bis (3,5-di-tert-butylsalicylidene-imine) (H 2 tBu salophen), has been exploited in coordination chemistry due to its facile synthesis, 4,5 multidentate nature, and redox-activity.…”

Structure of the {U13} polyoxo cluster U13O8Cl x (MeO)38–x (x = 2.3, MeO = methoxide)

“…Route B: [UCl 2 (salen) 2 (MeOH) 2 ] (H 2 salen = N,N 0 -bis-(salicylidene)ethylenediamine) was prepared according to a reported procedure (Radoske et al, 2020). A solution containing 7 mg of [UCl 2 (salen) 2 (MeOH) 2 ] in 1 mL of methanol was transferred into a quartz cuvette and sealed doubly with a lid and Parafilm in a dry and inert glove box filled with nitrogen gas.…”