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)

Two first-series transition metals have three unpaired electrons in complex ions of the type [MCl4]2-.

(a) What are the oxidation state and the identity of M in these complexes?

(b) Draw valence bond orbital diagrams for the two possible ions.

(c) Based on common oxidation states of first-series transition metals (Figure 21.6), which ion is more likely to exist?

<QUESTION REFERENCES FIGURE 21.6>

Constitutional isomers of a ruthenium(II) coordination compound are shown below.

(a) Give the formula and name for structures 1-3.

(b) Which structures are linkage isomers? 

(c) Which structures are ionization isomers?

Tell how many diastereoisomers are possible for each of the following complexes, and draw their structures. 

(a) Pt(NH₃)₃Cl (square planar) 

(b) [FeBr₂Cl₂(en)]^-

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.

(a) Draw crystal field energy-level diagrams for a square planar and a tetrahedral nickel(II) complex, and show the population of the orbitals.

Cobalt(III) trifluoroacetylacetonate, Co(tfac)₃, is a sixc oordinate, octahedral metal chelate in which three planar, bidentate tfac ligands are attached to a central Co atom:

(a) Draw all possible diastereoisomers and enantiomers of Co(tfac)₃.

For each of the following complexes, draw a crystal field energy-level diagram, assign the electrons to orbitals, and predict the number of unpaired electrons.

(a) [Pt(NH3)4]2+ (square planar)