Abstract
Cis-MCl2(big), big = bis(1-methylimidazol-2-yl)glyoxal, M = Pt, Pd, were prepd. and characterized through electrochem., spectroscopy, and for M = Pt, by x-ray structure anal. The seven-membered chelate ring formed through N,N' coordination of the ligand big shows a boat conformation in agreement with d. functional theory (DFT) calcn. results. No significant intermol. interactions were obsd. for the platinum compd. Both the PdII and PtII complexes undergo reversible 1-electron redn. in CH2Cl2/0.1 M Bu4NPF6; the reduced palladium compd. disintegrates \textgreater-30°. EPR, UV-visible, and IR spectroelectrochem. studies were employed to study the monoanions. The anion radical complex [cis-PtCl2(big)].bul.- exhibits a well-resolved EPR spectrum with small but well-detectable g anisotropy and an isotropic 195Pt hyperfine coupling of 12.2 G. DFT calcns. confirm the spin concn. in the a-semidione part of the radical complex with small delocalization to the bis(imidazolyl)metal section. EPR and electroactive moieties can be linked to the cis-dichloroplatinum(II) group via imidazole coordination. [on SciFinder(R)]
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