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Spectroscopic and Electrochemical Behavior of Cyclometalated Pd(II) Complexes
Author(s) -
Maestri Mauro,
Sandrini Diana,
Balzani Vincenzo,
von Zelewsky Alex,
Jolliet Philippe
Publication year - 1988
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19880710117
Subject(s) - chemistry , ligand (biochemistry) , electrochemistry , quinoline , luminescence , deprotonation , metal , absorption (acoustics) , absorption spectroscopy , pyridine , photochemistry , crystallography , redox , medicinal chemistry , inorganic chemistry , electrode , receptor , organic chemistry , ion , biochemistry , physics , optoelectronics , quantum mechanics , acoustics
The absorption and emission spectra, emission lifetimes, luminescence quantum yields, and electrochemical behavior of the complexes Pd(Phpy) 2 , Pd(Thpy) 2 , and Pd(bhq) 2 (Phpy − , Thpy − , and bhq − , and bhq − are the deprotonated forms of 2‐phenylpyridine, 2‐(2‐thienyl)pyridine, and benzo[ h ] quinoline, respectively) have been studied, and the results obtained have been compared with those available for Pt(II) and Pt(IV) complexes containing the same ligands. The intense ligand‐centered absorption bands below 340 nm are strongly perturbed by matalation, and the absorption features in the 340–450‐nm region are likely to include contributions from formally metal‐to‐ligand charge‐transfer transitions. The structured luminescence spectra observed at 77 K (lifetimes are 0.48, 0.28 and 2.6 ms for Pd(Phpy) 2 , Pd(Thpy) 2 , and Pd(bhq) 2 , respectively) have been assigned to transitions having mainly ligand‐centered character, with an increasing metal‐to‐ligand charge‐transfer contribution in going from Pd(bhq) 2 to Pd(Phpy) 2 and to Pd(Thpy) 2 . The complexes Pd(phpy) 2 and Pd(thpy) 2 show two reversible one‐electron reduction waves, whereas reduction of Pd(bhq) 2 is irreversible, as is the oxidation of the three complexes.