InterviewSolution
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InterviewSolution
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Atomic numbers of `Cr` and `Fe` are respectively `24` and `26`. Which of the following is paramagnetic with the spin of the electron?A. (a) `[Cr(NH_3)_6]^(3+)`B. (b) `[Fe(CO)_5]`C. (c) `[Fe(CN)_6]^(4-)`D. (d) `[Cr(CO)_6]` |
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Answer» Correct Answer - A `[Fe(CN)_6]^(4-)` is diamagnetic (`Fe^(2+)` has `3d^6` configuration and the 6 electron pairs up in three d-orbitals followed by `d^2sp^3`-hybridization). `[Cr(NH_3)_6]^(3+)` is paramagnetic (`Cr^(3+)` has `3d^3` configuration. Hybridization is `d^2sp^3`. Due to 3 unpaired electrons it is paramagnetic) `[Cr(CO)_6:Cr(Z=25): [Ar]^(18)4s^1, 3d^5`. The one `4s`-electron pairs up with five `3d`-electrons in three `d`-orbitals. This is followed by `d^2sp^3`-hybridization to give octahedral complex. No unpaired electron and hence complex is diamagnetic. `Fe(CO)_5: Fe(Z=26): [Ar]^(18) 4s^2, 3d^6`. The six electrons in d-subshell pairs up in three d-orbitals. This is followed by `d^2sp^3`-hybridization to give octahedral geometry with one vacant hybridized orbital. The resulting shape of the complex is square-based pyramid. As there is no unpaired electron, the complex is diamagnetic. |
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