Introduction

The purpose of the project is to explore different phosphine complexes of several metals. To this end, the student will conduct several quantummechnical calculations using Spartan 2010 using the PM6 (additional calculations using a higher level i.e., HF or DFT can be included if desired), and compared them with known data (crystal structure, infrared spectra, ⁹⁵Mo-NMR and ³¹P-NMR data) to assess the quality of the predictions.

Assignment

The instructor will assign the student a ligand. The student will have to calculate the properties for the following compounds

1. All M(CO)_xL_y stereoisomers

2. Free ligand

3. Metal carbonyl compound

Report

Results

The results of the calculations is summarized in a table form containing the following information with an appropriate diagram

1. Distances: M-E (individual and average), M-C, (individual and average), C-O (individual and average), E-C (individual and average)

2. Bond angeles: <(E-M-E), <(C-M-C) (individual and average), <(M-C-O) (individual and average), <(C-E-C) (individual and average)

3. Natural charges: M, E, C (or carbonyl groups)

4. Infrared data: n(CO), n(M-E)

Discussion

1. For the neutral compounds, compare the obtained results with the existing literature data

a. Are the obtained distances and bond angles reasonably close to the known X-ray structures? If not, what is different? (Hint: Show a table side by side)

b. Can the chemical shifts in the M-NMR and the NMR spectrum of the central atom of the ligand (i.e., ³¹P-NMR) be explained when comparing the complexes with M(CO)_x+y and the ligand itself?

c. Are the observed frequencies for the Mo-E and the C-O modes reasonable?

d. Which of the two configurations is more stable? By how much?

Submission

The report has to be submitted by March 13, 2015 at 12:00 pm. The submission is in paper version and online (turnitin.com). The student will also have to submit the obtained data files in electronic form to the instructor (via flash drive because the files are often corrupted when send via email). The assignment is worth 25 points.

Hints

1. If the calculations are terminating before they are complete, make sure to resubmit them. Make sure that the converge and symmetry boxes are checked.

2. A quick way to find structural information is the use of the CDCC software. The package contains a program called Conquest, which allows to search for structural motifs i.e., Mo(CO)₄P₂, or specific structures. After running the search, the data can be transferred to mercury, which allows for the visualization of the data i.e., bond distances, angles, etc.

3. If you have problems using Spartan 2010, please consult your instructor asap to get a quick tutorial.