Synthesis and characterisation of Pd(II) complexes with a derivative of aminoazobenzene

Mechanism of Mechanochemical C−H Bond Activation in an Azobenzene Substrate by PdII Catalysts

“…Analogous IAG and ILAG of AZB and chloride precursors in 1:1 and 1:2 molar ratios afforded a mixture of AZB , mono‐ and dipalladated products. This could be due to a side reaction in which the released chlorides consume the Pd precursor and form chloropalladate species that, according to the study of azobenzene palladation in DMF, undergo palladation but very slowly, thus retarding the reaction.…”

“…Rate of transformation of AZB into the first adducts increases in the following order of additives: none<MeCN<DMF<H 2 O indicating that the listed liquids assist the formation of the first intermediate (Figure ). Either adducts with monomeric [PdCl 2 ( AZB )(Solvent)], that is, mA α ‐I and mA β ‐I , or dimeric structure [PdCl 2 ( AZB )] 2 , for example, cis ‐( dA α ‐I ) and trans ‐( dA α ‐I ), are expected (Figure ) . Differentiating monomeric from dimeric adducts in situ by Raman spectroscopy is not feasible as their spectra, according to calculations, should show only minor differences (Figures S55–S57).…”

“…Thus, a detailed IR and NMR spectral analysis was necessary to gain important data on possible isomerism during milling and possible ancillary ligands bound to Pd centers. 1 H NMR spectra of all reaction mixtures with chloride precursors after 15–45 minutes of milling show multiple sets of signals, typical for coordination complexes of aminoazobenzenes, due to presence of monomeric or dimeric alpha or beta isomers containing Pd bound to alpha or beta azo‐nitrogen (Figure S14). According to the previous studies of azobenzene palladation, alpha isomers should be dominant over beta isomers.…”

“…1 H NMR spectra of all reaction mixtures with chloride precursors after 15–45 minutes of milling show multiple sets of signals, typical for coordination complexes of aminoazobenzenes, due to presence of monomeric or dimeric alpha or beta isomers containing Pd bound to alpha or beta azo‐nitrogen (Figure S14). According to the previous studies of azobenzene palladation, alpha isomers should be dominant over beta isomers. IR spectra of the PdCl 2 (MeCN) 2 reaction mixtures (see Figure S23 for ILAG‐DMF/PdCl 2 (MeCN) 2 ) reveal that the isolated mA α ‐I and its beta isomer mA β ‐I are dominant adducts in both PdCl 2 (MeCN) 2 reactions (Figure ).…”

Cyclopalladated Azo–linked Porous Polymers in C–C Bond Forming Reactions

“…The shoulder at ∼120 ppm was assigned to the ortho‐carbons ( b ), and the band at ∼130 ppm to other aromatic carbons ( c,f ). The 13 C CP‐MAS NMR spectrum of cyclo‐Pd(II)/PP‐2 (Figure b) has a characteristic shoulder at ∼158 ppm ( b’ ) for cyclopalladated azobenzene …”