Exercise 8 | The Chemistry of the Transition Metals

[Cr(CN)₆]^4-: oxidation state of Cr = charge – 6 x oxid. state CN^- = - 4 + 6 = + 2

Cr (II) complex: [Ar] 3d⁴ ⇒ 4 d-electrons

CN^- ⇒ low spin ⇒ electrons will first fill the t_2g orbitals before occupying the higher-energy e_g orbitals ⇒ t_2g⁴ e_g⁰

⇒ 2 unpaired electrons

[FeF₆]^3-: oxidation state of Fe = charge – 6 x oxid. state F^- = - 3 + 6 = + 3

Fe (III) complex: [Ar] 3d⁵ ⇒ 5 d-electrons

F^- ⇒ high spin ⇒ d electrons occupy the e_g orbitals before they pair up in the t_2g orbitals ⇒ t_2g³ e_g²

⇒ 5 unpaired electrons

[Rh(NH₃)₆]³⁺: oxidation state of Rh = charge – 6 x oxid. state of NH₃ = + 3 – 0 = + 3

Rh (III) complex: [Kr] 4d⁶ ⇒ 6 d-electrons

low spin ⇒ electrons will first fill the t_2g orbitals before occupying the higher-energy e_g orbitals ⇒ t_2g⁶ e_g⁰

⇒ no unpaired electrons