Synthesis and X-ray Crystal Structure of [U(η-C8H8)(HMPA)3][BPh4], the First Cationic Monocyclooctatetraenyl Compound of Uranium (III), and its Neodymium Homologue

Abstract

The title compound was synthesized in 88% yield by reducing the uranium(IV) dication [U(COT)(HMPA)3][BPh4]2 (COT = η‐C8H8) with sodium amalgam while the neodymium analogue was prepared by substitution of the THF ligands in [Nd(COT)(THF)4][BPh4]. Comparison of the crystal structures of the complexes [M(COT)(HMPA)3][BPh4] (M = U, Nd, Sm) shows that the variations in the M−ligand bond lengths simply reflect the differences in the ionic radii of the metals.

Synthesis of Arene-Soluble Mixed-Metal Uranium/Zirconium Complexes Using the Dizirconium Nonaisopropoxide Ligand

“…In 2 , the 2.564(4)−2.621(4) Å U−O distances are larger than those in 1 , which is consistent with the higher formal coordination number of 2 generated by the (C 8 H 8 ) 2- versus [I 2 (THF)] 2- ligand set. The 2.743(7) Å average U−C(C 8 H 8 ) distance in 2 is similar to those found in the only three other structurally characterized U III −(C 8 H 8 ) complexes, (C 8 H 8 )(C 5 Me 5 )U(4,4'-dimethyl-2,2'-bipyridine),19a [K(diglyme)][U(C 8 H 7 Me) 2 ],19b and [(C 8 H 8 )U(HMPA) 3 ][BPh 4 ],19c in which the average distances are 2.703, 2.707(7), and 2.71(4) Å, respectively. This suggests that the dzni ligand is sterically equivalent to the [(C 5 Me 5 )(Me 2 bpy)] - and [(C 8 H 7 Me)K(diglyme)] - ligand sets.…”

“…X-ray crystallography was employed to definitively characterize 2 (Figure ). 2 represents one of the few U(III)/C 8 H 8 2- complexes reported in the literature 2 Plot of [Zr 2 (O i Pr) 9 ]U(C 8 H 8 ), 2 , with thermal ellipsoids drawn at the 30% probability level. …”

“…The oxidation potentials of 1 and 2 are comparable to the few U(III) values reported in the literature. (C 8 H 8 )(C 5 Me 5 )U(4,4'-dimethyl-2,2'-bipyridine) has a reported redox potential of −0.69 V vs SHE (−1.1 V vs ferrocene) 19a.…”

Cationic Organometallic Complexes of Scandium, Yttrium, and the Lanthanoids

“…The syntheses of two cationic cyclooctatetraene neodymium complexes, [Nd( η 8 -C 8 H 8 )(THF) 4 ] + [BPh 4 ] - ( 4 ) − and [Nd( η 8 -C 8 H 8 )(HMPA) 3 ] + [BPh 4 ] - ( 5 ), , have been presented. The reaction of the neutral borohydride complex [Nd( η 8 -C 8 H 8 )(BH 4 )(THF) 2 ] with a slight excess of [NEt 3 H] + [BPh 4 ] - in THF afforded 4 in good yield.…”

Uranocene. The First Member of a New Class of Organometallic Derivatives of the f Elements

“…Another type of cationic C 8 H 8 uranium complex was prepared by the action of [Et 3 NH]BPh 4 on C 8 H 8 U(BH 4 ) 2 ·THF (eq 24) The monocation could be converted to the novel dication [C 8 H 8 U(HMPA) 3 ] 2+ by reaction with [Et 3 NH]BPh 4 in the presence of HMPA in refluxing THF solution 15 Christopher C. Cummins (photo by Atlantic Photo Service, Inc.; reproduced by permission of Atlantic Photo Service, Inc., and Christopher C. Cummins). …”