1610458-75-7Relevant academic research and scientific papers
Regioselective and regiospecific C(naphthyl)-H bond activation: Isolation, characterization, crystal structure and TDDFT study of isomeric cyclopalladates
Biswas, Achintesh Narayan,Neogi, Debatra Narayan,Das, Purak,Choudhury, Amitava,Bandyopadhyay, Pinaki
, p. 147 - 155 (2014)
The C2(naphthyl)-H, C3(naphthyl)-H and C8(naphthyl)-H bonds of the naphthyl group present in a group of naphthylazo-2′-hydroxyarenes (H2L) have been activated at room temperature by palladium(II) and stable cyclopalladates of the type [PdL(B)] have been isolated in presence of neutral Lewis bases (B). The activation of C2(naphthyl)-H and C8(naphthyl)-H bonds of 1-(2′-hydroxynaphthylazo) naphthalene (H2L1) lead to the formation of isomeric cyclopalladates 2a & 2b respectively. The single crystal X-ray structures of both the isomers show the naphthylazonaphtholate is coordinated to palladium(II) as a dianionic terdentate C,N,O-donor and Lewis base B occupies the fourth position in the coordination sphere. The ortho-palladate (2a) contains both five-membered carbopalladacycle and azonaphtholato chelate ring whereas a five-membered carbopalladacycle and a six-membered azonaphtholato chelate ring are present in peri-palladate (2b). On the other hand, only C3(naphthyl)-H bond of 2-(2′-hydroxyarylazo) naphthalene (H2L2 & H2L3) has been found to be regiospecifically activated by palladium(II). The role of auxiliary donors on the regioselective and regiospecific C(naphthyl)-H bond activation and the rationale behind the formation of isomeric cyclopalladates have been discussed. All of the cyclopalladates absorb strongly in the ultraviolet and visible region. The Time-dependent density functional theory (TDDFT) calculations reveal that the high energy absorptions are predominantly due to intraligand π-π* and the low energy absorptions originate from intraligand π-π* with a small admixture of metal-to-ligand charge-transfer transitions.
