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Uranium versus Thorium: Synthesis and Reactivity of [η⁵ -1,2,4-(Me₃ C)₃ C₅ H₂ ]₂ U[η² -C₂ Ph₂ ].

ABSTRACT: The synthesis, electronic structure, and reactivity of a uranium metallacyclopropene were comprehensively studied. Addition of diphenylacetylene (PhC≡CPh) to the uranium phosphinidene metallocene [η⁵ -1,2,4-(Me₃ C)₃ C₅ H₂ ]₂ U=P-2,4,6-tBu₃ C₆ H₂ (1) yields the stable uranium metallacyclopropene, [η⁵ -1,2,4-(Me₃ C)₃ C₅ H₂ ]₂ U[η² -C₂ Ph₂ ] (2). Based on density functional theory (DFT) results the 5f orbital contributions to the bonding within the metallacyclopropene U-(η² -C=C) moiety increases significantly compared to the related Th^IV compound [η⁵ -1,2,4-(Me₃ C)₃ C₅ H₂ ]₂ Th[η² -C₂ Ph₂ ], which also results in more covalent bonds between the [η⁵ -1,2,4-(Me₃ C)₃ C₅ H₂ ]₂ U²⁺ and [η² -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 [η⁵ -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.

SUBMITTER: Wang D

PROVIDER: S-EPMC8251885 | biostudies-literature |

REPOSITORIES: biostudies-literature

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