# Is this complex square planar or tetrahedral?

1. The complex ion [AuCl4]- is paramagnetic. Is this complex square planar or tetrahedral? Explain and show the labeled d-orbital splitting diagrams for both coordination geometries. You will need to refer to the definition of a paramagnetic molecule, as well as the likelihood of e- pairing in both the square planar and tetrahedral fields. 2) Compound/ Apparent Color [Osβ 6 ] 3+ orange [Osβ 5 Ψ] 3+ purple [Osβ 5 Ω] 3+ red Given the octahedral complexes in the table below, answer the following question Which is the most strongly binding ligand between β, Ψ, and Ω? Explain how you can tell, and draw the relevant, labeled d-orbital splitting diagram for each complex, making sure that all three diagrams are on the same energy scale and can thus be compared using your sketch. Refer to how you determine the HOMO-LUMO energy gap, and how you determine the relative absorbed light energies. 3)For octahedral field a) Sketch an energy level diagram showing the d-orbital splitting, and label all orbitals and give symmetry designations for the two d-orbitals sets. b) Sketch the d-orbitals relative to ligand positions in the Cartesian axis system, and explain the resulting d-orbital splitting. 4) Given the following equilibrium: Co2+ (aq) + 6 Cl- (aq) ⇌ CoCl64- (aq) a. Co2+ is pink, and CoCl64- is blue. When you heat up a pink solution containing Co2+ and Cl-, the solution turns blue. Therefore, what is the sign of ΔH (+/-) for the above reaction? Explain your reasoning b. If you had a solution in which Co2+, Cl-, and CoCl64- were in equilibrium, and you added to it some HCl , how would you expect the color of the solution to change? (would it get more pink or blue?) Explain briefly.