Mapping the unpaired electron density in [Pt(bipy)L2]- (bipy=2,2′-bipyridine; L=Cl-, CN-, 13CN-): A combined EPR–ENDOR–theoretical study
- 1 January 1998
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions
- Vol. 94 (19) , 2985-2991
- https://doi.org/10.1039/a804498h
Abstract
The X-band EPR and electron–nuclear double resonance (ENDOR) spectra of the formally , 17-electron radical anions [Pt(bipy)L2]− (bipy = 2,2′-bipyridine; L = Cl−, CN−, 13CN−) are reported. The 195Pt (I = 1/2, 34%) anisotropic hyperfine matrices are analysed in terms of both 5d and 6p contributions to the singly occupied molecular orbitals (SOMOs). For L = Cl− there is 5.0% 5dyz and 7.6% 6pz character, for L = CN−there is yz and 13.1% 6pz. The bulk of the unpaired electron density is delocalised about the bipy π* system and ENDOR spectra reveal the superhyperfine couplings to the 1H, 14N and 13C (L = 13CN−) nuclei. The unpaired electron densities in the 14N 2pz orbitals contributing to the π* systems are calculated to be 12% and 4% for L = Cl− and CN−, respectively. The cyanide π-orbitals make little contribution to the SOMO for [Pt(bipy)(CN)2]−. There is a good agreement with density functional theory (DFT) MO calculations on the radical anions. DFT calculations also show the atomic orbital compositions of the lowest unoccupied (LU) MO of [Pt(bipy)L2] and the SOMO of [Pt(bipy)L2]− to be virtually identical.Keywords
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