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DFT studies of isomerization in palladium(IV) chemistry and alkyl halide transfer from palladium(IV) to palladium(II)
journal contributionposted on 2023-05-19, 21:06 authored by Allan CantyAllan Canty, Alireza AriafardAlireza Ariafard
A DFT study of alkyl halide exchange from Pd(IV) to Pd(II) centers supports proposals for an SN2 process in which nucleophilic Pd(II) square-planar complexes attack the axial alkyl group in electrophilic squarepyramidal Pd(IV) centers, leading to transfer of R+ from Pd(IV) to Pd(II) involving a transition structure of the form [R2(bpy)··R··PdR2 (bpy)]+ (bpy = 2,20’ -bipyridine). Computation accounts for the selectivity in benzyl (Bn) over methyl transfer from PhMeBnPdIV(bpy)Br to Me2PdII(bpy), giving PhMePdII(bpy) and BnMe2PdIV(bpy). Transition structures are formed by the interaction of a dz2-like HOMO at the Pd(II) nucleophile and the Pd-C σ* LUMO at the cationic Pd(IV) electrophile. Isomerization of octahedral palladium(IV) complexes via halide loss followed by involvement of trigonal-bipyramidal transition structures to facilitate isomerization is also examined. A lower barrier for Bn+ than Me+ transfer is attributed to stabilisation of the transition structure by delocalisation of positive charge within the benzyl group, reflected in a higher total charge density for the benzyl group than found for the methyl group.
Publication titleJournal of Organometallic Chemistry
Department/SchoolSchool of Natural Sciences
PublisherElsevier Science Sa
Place of publicationPo Box 564, Lausanne, Switzerland, 1001
Rights statementCopyright 2018 Elsevier B.V.