Abstract
The first cyclometallated compounds of some 2,6-diarylpyridines ( 2) and the related ligand, 5,6,8,9-tetrahydrodibenz[ c, h]acridine ( 3) were prepared and characterized as acetato-bridged palladium(II) dimers: [Pd( 2 or 3)OAc] 2. Inseparable isomers ( syn,trans and syn,cis) were indicated by NMR, with the syn,trans isomer invariably predominating. With an unsymmetrical 2, both isomers reuslting from metallation of either one ring or the other dissimilar ring were observed in relative amounts which support the hypothesis that palladium makes an electrophilic attack on the aryl ring during cyclopalladation. Efforts to force trans-dimetallation, previously only observed with 2,6-dialkylpyridines, were unsuccessful. NMR evidence for palladium-to-carbon multiple bonding (M dπ → L π * ) (and a shorter than single PdC bond determined from an X-ray crystal structure), coupled with the near 120° angle restriction on sp 2 carbons, suggests that these diarylpyridines are not sterically suited for dimetallation. The benzo[ h]quinoline ( 1) cyclopalladated complexes. [Pd( 1)OAc] 2, and [Pd( 1)dtc] (dtc = N, N-diethyldithiocarbamate) have been fully characterized by 200 MHz NMR.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
