24. Transition Metals and Coordination Compounds

Determine if the following complex ion is either paramagnetic or diamagnetic: [CoF₄]^2–.

Four-coordinate metals can have either a tetrahedral or a square-planar geometry; both possibilities are shown here for [PtCl₂ (NH₃)₂].

a. What is the name of this molecule?

b. Would the tetrahedral molecule have a geometric isomer?

c. Would the tetrahedral molecule be diamagnetic or paramagnetic?

d. Would the square-planar molecule have a geometric isomer?

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For each of the following, (i) give the systematic name of the compound and specify the oxidation state of the transi-tion metal, (ii) draw a crystal field energy-level diagram and assign the d electrons to orbitals, (iii) indicate whether the complex is high-spin or low-spin (for d4 - d7 complexes), and (iv) specify the number of unpaired electrons.

(e) [Pt(NH3)4](ClO4)2

For each of the following, (i) give the systematic name of the compound and specify the oxidation state of the transi-tion metal, (ii) draw a crystal field energy-level diagram and assign the d electrons to orbitals, (iii) indicate whether the complex is high-spin or low-spin (for d4 - d7 complexes), and (iv) specify the number of unpaired electrons.

(f) Na2[Fe(CO)4]

Nickel(II) complexes with the formula NiX₂L₂, where X is Cl^- or N-bonded NCS^- and L is the monodentate triphenylphosphine ligand P(C₆H₅)₃, can be square planar or tetrahedral.

(b) If NiCl₂L₂ is paramagnetic and Ni(NCS)₂L₂ is diamagnetic, which of the two complexes is tetrahedral and which is square planar?

An alternative to cyanide leaching of gold ores is leaching with thiocyanate ion, which forms a square planar gold(III) complex, [Au(SCN)₄]^-.

(b) Draw a crystal field energy-level diagram for [Au(SCN)₄]^-, and predict the number of unpaired electrons.

What hybrid orbitals are used by the metal ion and how many unpaired electrons are present the complex ion [VCl₄]^- with tetrahedral geometry?

(a) sp³; 2 unpaired electrons

(b) sp³; 3 unpaired electrons

(c) sp³d²; 3 unpaired electrons

(d) sp³d²; 4 unpaired electrons

Give a valence bond description of the bonding in each of the following complexes. Include orbital diagrams for the free metal ion and the metal ion in the complex. Indicate which hybrid orbitals the metal ion uses for bonding, and specify the number of unpaired electrons. 

(b) [NiBr₄]^2- (tetrahedral) 

For each of the following complexes, describe the bonding using valence bond theory. Include orbital diagrams for the free metal ion and the metal ion in the complex. Indicate which hybrid orbitals the metal ion uses for bonding, and specify the number of unpaired electrons. 

(a) [AuCl4]2 (square planar)

For each of the following complexes, describe the bonding using valence bond theory. Include orbital diagrams for the free metal ion and the metal ion in the complex. Indicate which hybrid orbitals the metal ion uses for bonding, and specify the number of unpaired electrons. 

(b) [Ag(NH3)2]+

Give a valence bond description of the bonding in each of the following complexes. Include orbital diagrams for the free metal ion and the metal ion in the complex. Indicate which hybrid orbitals the metal ion uses for bonding, and specify the number of unpaired electrons.

(c) [Fe(CN)6]3- (low-spin)

Give a valence bond description of the bonding in each of the following complexes. Include orbital diagrams for the free metal ion and the metal ion in the complex. Indicate which hybrid orbitals the metal ion uses for bonding, and specify the number of unpaired electrons.

(a) [Ti(H2O)6]3+

Give a valence bond description of the bonding in each of the following complexes. Include orbital diagrams for the free metal ion and the metal ion in the complex. Indicate which hybrid orbitals the metal ion uses for bonding, and specify the number of unpaired electrons.

(d) [MnCl6]32 (high-spin)