Uranium versus Thorium: Synthesis and Reactivity of [η5‐1, 2, 4‐(Me3C)3C5H2]2U[η2‐C2Ph2]. Issue 22 (16th March 2021)

• Record Type: Journal Article
• Authors: Wang, Deqiang; Ding, Wanjian; Hou, Guohua; Zi, Guofu; Walter, Marc D.
• Is Part Of: Chemistry. Volume 27:Issue 22(2021)
• Page Start: 6767
• Page End: 6782
• Publication Date: 2021-03-16
• Subjects: actinides -- bonding -- metallacyclopropene complexes -- reactivity -- uranium; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202100089
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The synthesis, electronic structure, and reactivity of a uranium metallacyclopropene were comprehensively studied. Addition of diphenylacetylene (PhC≡CPh) to the uranium phosphinidene metallocene [ η 5 ‐1, 2, 4‐(Me3 C)3 C5 H2 ]2 U=P‐2, 4, 6‐ t Bu3 C6 H2 (1 ) yields the stable uranium metallacyclopropene, [ η 5 ‐1, 2, 4‐(Me3 C)3 C5 H2 ]2 U[ η 2 ‐C2 Ph2 ] (2 ). Based on density functional theory (DFT) results the 5f orbital contributions to the bonding within the metallacyclopropene U‐( η 2 ‐C=C) moiety increases significantly compared to the related Th IV compound [ η 5 ‐1, 2, 4‐(Me3 C)3 C5 H2 ]2 Th[ η 2 ‐C2 Ph2 ], which also results in more covalent bonds between the [ η 5 ‐1, 2, 4‐(Me3 C)3 C5 H2 ]2 U 2+ and [ η 2 ‐C2 Ph2 ] 2− fragments. Although the thorium and uranium complexes are structurally closely related, different reaction patterns are therefore observed. For example, 2 reacts as a masked synthon for the low‐valent uranium(II) metallocene [ η 5 ‐1, 2, 4‐(Me3 C)3 C5 H2 ]2 U II when reacted with Ph2 E2 (E=S, Se), alkynes and a variety of hetero‐unsaturated molecules such as imines, ketazine, bipy, nitriles, organic azides, and azo derivatives. In contrast, five‐membered metallaheterocycles are accessible when 2 is treated with isothiocyanate, aldehydes, and ketones. Abstract : The intrinsic reactivity of a stable uranium metallacyclopropene complex, [ η 5 ‐1, 2, 4‐(Me3 C)3 C5 H2 ]2 U( η 2 ‐C2 Ph2 ), was evaluated and compared to that of other uranium and thorium metallacyclopropenes. Although structurally similar, the thorium and uranium metallacyclopropenes exhibit distinctively different reactivity.