|U n i v e r s i t y|
|Course: CHEMISTRY||Number: 341/2||Section: X|
|Instructor: P.H. Bird|
|Examination: Final||Date: 11th December, 2001||Time: 14:00-17:00 pm||# of pages: 12|
|Materials Allowed: Data sheets attached to this paper - no other materials are allowed.
Calculators Allowed: Yes
The data sheets attached consisted of:
|Special Instructions: Please attempt all questions: theyu carry equal marks. Write your answers in the spaces provided on this paper. Be sure to give adequate explanations for your answers. Use the back of the pages for rough work and, if necessary, for extra space. If you continue an answer on the back of a page, please indicate this clearly.|
Student Number: _________________________________________________
(m means bridging)
Do not forget ox2- is a bidentate ligand.
Show its full structure somewhere in your answer.
To get full marks:
|Complex||High Spin, Low Spin
or not applicable
In units of D
|[Co(NH3)6]3+||Low spin||t2g6(eg0)||6 x -2/5Do = 1.2Do|
Find dn, and use either the table of terms and the associated diagrams, or the appropriate Tanabe-Sugano diagram to get the ground state. Use the Tanabe Sugano diagram to determine which transitions are spin-allowed. The question is not asking you to estimate the frequency of the transitions, but you could do that too with the information you are given. you would need to estimate Do and a B value from the free ion values given.
You may need to consider the possible presence of spin forbidden or charge transfer bands to answer this, This time some rough calculations are needed to support your conclusions.
Find dn's, and, if appropriate, use either the table of terms and the associated diagrams, or the correct Tanabe-Sugano diagram to get the ground state. Use the Tanabe-Sugano diagram to determine which transitions are spin-allowed. The question is not asking you to estimate the frequency of the transitions.
You need to know the trans-directing order and order of nucleophilicity for the ligands involved to answer this.
To answer these, you need to consider:
- Lability/inertness of reactants and products.
- Occupancy of antibonding eg orbitals, before and after electron transfer, which might require bond length changes.
You know it or you don't!
Not covered in Fall 2003.