File(s) under permanent embargo
Phosphine- and pyridine-functionalized N-heterocyclic carbene methyl and allyl complexes of palladium. Unexpected regiospecificity of the protonation reaction of the dimethyl complexes
journal contribution
posted on 2023-06-10, 01:35 authored by Andreas A Danopoulos, Nikolaos Tsoureas, Stuart A Macgregor, Christopher SmithSquare planar neutral dimethyl and cationic allyl complexes of palladium with the electronically nonsymmetric diphenylphosphinomethyl- and pyridyl-N-heterocyclic carbene ligands have been synthesized and characterized. The products from the protonation of the dimethyl complexes with 1 equiv of acid at low temperatures are monomethyl cations, the exact nature of which is dependent on the type of ligand; in pyridine-carbene complexes the Pd-Me bond cleaved is trans to the carbene, while for the phosphino-carbene complexes it is trans to the phosphine. Density functional calculations suggest that protonation in these complexes occurs directly at the methyl ligands and that the site of protonation determines the selectivity of Pd-Me cleavage. For the pyridine-carbene complexes there is a clear preference for protonation trans to the carbene. For phosphino-carbene complexes, however, the site of protonation depends on the steric bulk of the N-heterocyclic carbene ligand. Protonation trans to carbene is favored with small substituents (H, Me), but the bulky 2,6-Pri2C6H3 susbstituent induces protonation trans to the phosphine, as is seen experimentally.
History
Publication status
- Published
File Version
- Published version
Journal
OrganometallicsISSN
0276-7333Publisher
American Chemical SocietyExternal DOI
Issue
2Volume
26Page range
253-263Department affiliated with
- Chemistry Publications
Full text available
- No
Peer reviewed?
- Yes
Legacy Posted Date
2021-11-01First Compliant Deposit (FCD) Date
2021-10-30Usage metrics
Categories
No categories selectedKeywords
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC