5. Show how the d orbital splitting changes as an octahedral complex undergoes tetragonal distortion and eventually becomes a square planar complex. What is the spectrochemical series and what is its importance Using crystal field theory, (a) Draw the d-orbital electronic configuration of [Cr(CN)6]³ (b) How many unpaired electrons are present? (c) Calculate the CFSE and magnetic moment of the complex ion (c) If six Br groups were substituted for the six CN groups to give [CrBr.]³ would you expect Ao to increase or decrease? Why? Describe how Ao changes as the charge on the metal changes from M² to M and how it changes between a first row, second row or third row transition element.

15. Describe clearly how crystal field theory explains satisfactorily the magnetic moment of transition metal complexes. Which complex has the larger crystal field splitting? Give reasons for your answer. (i) [Co(CN)6] or (ii) [Co(H2O)²+ or (iii) [Co(NH)6] or [Co(NH3)6] [Co(H_O)] [Rh(NH3)]* What relationship exist between A (the crystal field splitting) and the pairing energy (P) in determining whether a given complex will be high spin or low spin.

Part 1 See Periodic Table Draw the major resonance contributor for the skeletal arrangement CNNO 2 (arrangement a). Include all nonbonding electrons and all nonzero formal charges. The skeleton has been given to you. Н Ν HCNO SE F ·N—N; ☑ P Cl Br I