(barycentre). Calculating the CFSE for the Iron complexes Complex: [Fe(H O) ] + High Spin Complex Low spin complex Electronic configuration in isotropic field : d No. of paired electrons (n'p)= ; Therefore, E iso = XII U5 Coordination XII U5 Coordination - - - - High Spin Complex Low spin complex Electronic configuration( for high spin com- plex) : t 2g e g CFSE = {[ (- . )+ ( .
)] Δ o + × P} - { } = Electronic configuration ( for low spin com- plex) : t 2g e g CFSE = {[ (- . )+ ( . )] Δ o + × P} - { } = - Δ o + 2P = (- ×14000) + ( × 30000) = 32000 cm - High positive CFSE value indicates that low spin complex is not a favourable one. Actual nature of [Fe(H O) ] + High spin (Spin free) Electronic configuration of central metal ion t 2g e g Magnetic property No.
of unpaired electrons = ; Hence paramagnetic Magnetic moment (Using spin only formula) µ s = n(n+ ) = ( + ) = . BM Complex: [Fe(CN) ] - High Spin Complex Low spin complex Electronic configuration in isotropic field : d5 No. of paired electrons (n'p)= ; Therefore, E iso = Ligand field: Electronic configuration : t 2g e g CFSE = {[ (- . )+ ( .
)] Δ o + × P} - { } = Ligand field Electronic configuration : t 2g e g CFSE = {[ (- . )+ ( . )] Δ o + × P} - { } = - Δ o + 2P = (- ×35000) + ( × 30000) = -10000 cm - Negative CFSE value indicates that low spin complex is favoured XII U5 Coordination XII U5 Coordination - - - - Nature of the complex Low spin (Spin paired) Electronic configuration of central metal ion t 2g e g Magnetic property