THE EPR SPECTRA OF TETRADENTATE SCHIFF BASE COMPLEXES OF COPPER (II) I. N,N'-Bis-(acetylacetone) ethylenediimine and N,N'-Bis-(1,1,1-trifluoroacetylacetone) ethylenediimine |
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Abstract: | Abstract The EPR spectrum of N, N'-bis-(acetylacetone)ethylenediimino Cu(II), Cu-en(acac)2], and N, N'-bis-(1,1,1-trifluoroacetylacetone)ethylenediimino-Cu(II), Cu-en(tfacac)2], have been studied in doped single crystals of the corresponding Ni(II) chelate. The parameters in the usual doublet spin-Hamiltonian are found to be: Cuen(acac)2], gz =2.183 ± 0.003, gx =2.047 ± 0.004, gy =2.048 ± 0.004, Az =204.8 × 10?4cm?1, Ax =31.5 × 10?4cm?1, Ay =27.1 × 10?4 cm?1, AzN= 12.8 × 10?4 cm?1 and AxN =AyN =14.3 × 10?4 cm?1: Cuen(tfacac)2], gz =2.192 ± 0.002, gx =2.048 ± 0.004, gy =2.046 ± 0.004, Az =200.8 × 10?4 cm?1, Ax =31.1 × 10?4 cm?1, Ay =28.3 × 10?4 cm?1, AzN =12.8 × 10?4 cm?1 and AxN =AyN =14.6 × 10?4 cm?1. These parameters are related to coefficients in the molecular orbitals of the complex. It is found that the α-bonding is quite covalent and there is significant in-plane σ-bonding. From the nitrogen hyperfine structure it is determined that the hybridization on the nitrogen is sp2. |
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Keywords: | EPR Spectra N N'-bis-(acetylacetone)ethylenediimino Cu(II) N N'-(1 1 1-trifluoroacetylacetone) ethylenediimino Cu(II) magnetic parameters molecular orbitals |
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