MOs in Inorganic Chemistry

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MOs in Inorganic Chemistry: The Exam

The EXAM

All the materials given to you are examined, this includes all the notes, tutorial and exam prep problems. The notes contain more material than is covered in the slides and you are expected to do some additional reading on the topic. In addition, you are expected to be able to make synoptic connections to your first and second year courses, principally physical chemistry and inorganic chemistry.

Remember my goal is not to be "mean" in the exam, but to allow you to demonstrate your mastery of the topic. I am much more interested in you knowing how than in you memorising bits and pieces, so if you hit a problem you cannot do, do as much of it as you can because I will incrementally mark it for each aspect that you show me you can do. I identified in the lectures which material I did expect you to know ie to have memorised, knowledge that you need to have "at hand" to be able to complete problems.

The course content has changed since 2014

Important Old exams do fully reflect the current course content:
  • the derivation of symmetry adapted MOs has been removed
  • the reduction formula and projection operator have been removed
  • the interpretation of computed MOs has been added
  • M-M bonding has been added
  • there is a much larger focus on TM complexes

The format of the exam

  • section (a) compulsory worth 8-12 marks
  • section (b) choice: answer two out of three questions 4-6 marks each
  • marked out of a total of 20

past exam papers are available from blackboard
I particularly encourage you to read the feeback comments from past papers, these are detailed and written for you!!

Examples with answers to work through

from the course so far:

  • from L1: producing a representation table, determining the symmetry of orbitals, improper rotations, an old exam question drawing the symmetry elements of borazine, finding and drawing all the symmetry elements for the tetrahedral point group.
  • Additional problems on diatomics (CN, CO, NO, N2, O2) focusing on mixing and linking to experimental PES, On-line interactive tutorial on CN-
  • from L2: revise the workshop from last year so you can carry out calculations, predict if BeH2 is linear or bent, the MO diagrams for linear H2O and CH2, MO diagram of planar NH3, Walsh diagram distorting to trigonal pyramidal NH3 including mixing, forming the MO diagram for H3BNH3 and computing the real orbitals of BeH2, NH3, H3BNH3.
  • from P1: the MO diagram of BH3, and computing the real orbitals of BH3
  • from L3: MO diagram of FHF, splitting energies, an advanced problem on the allene fragment (C3H5), connecting with your QM course (Huckel theory) and computing the real orbitals of FHF and C3H5
  • from L4: the MO diagram of H2CN(an old exam question) and the MO diagram of I3- (an old exam question) and computing the real orbitals of I3-
  • workshop: the MO diagram of PL5
  • from L5: the energy diagram for Mo2, degenerate MOs in Mo2, improper rotations in Oh
  • from L6: explain colour changes in Ni TM complexes, explain why H– and RH– are appear relatively high in the spectrochemical series, construct the L6 ligand FOs from L4+L2 fragments, show the short-cuts for determining symmetry label, form the energy diagram for ML4L'2
  • from T2: Examining end on vs side on binding of N2 and explaining why M-CO bonds are stronger than M-N2 bonds using MO theory
  • from P2: The energy diagram for ML4
  • from L7: why can the octahedral splitting parameter be difficult to identify, whe can the oxo ligand O2- convert between double and triple bonds, key MOs of O2 coordinating side on and end on, bent end-on coordination, comparing the key MOs for H2O and O2- ligands, explain using MO theory and diagrams why cis-[CoCl2(NH3)4]+ is violet and trans-[CoCl2(NH3)4]+ is green
  • from L8: use MO diagrams to explain how a large octahedral splitting could be obtained, explain (employing an energy diagram including key MOs) why NH3 generates a larger octahedral splitting than H2O, rationalise why N2 prefers to coordinate end-on, construct an energy diagram for M2L10 where L are sigma-donor ligands

new problems to test yourself on:

  • additional examples: constructing the octahedral ligand set, explaining the bonding antibonding character of a MO (an old exam question), the MX2L4 energy diagram and MOs (an old exam question) pdf
  • pdf form a MO diagram for MgCl2
  • pdf form a MO diagram for H2CO, pop_ch2O_opt_freq.fchk
  • pdf form a MO diagram of PH3Cl2, pop_ph3cl2_opt_freq.fchk
  • pdf form a Walsh diagram for H4

use the sidebar to access specific lecture, workshop and problems class material.

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