Substitution Reaction of Molybdenum Hexacarbonyl: the Use of Infrared Spectroscopy as a Structural Tool in Metal Carbonyl Chemistry.

School of Chemistry @ Pietermaritzburg

University of KwaZulu Natal
Chemistry 310

Substitution reaction of Molybdenum Hexacarbonyl: the use of infrared spectroscopy as a structural tool in metal carbonyl chemistry.

Abstract

The synthesis of isomer A and B of [Mo(CO)4(PPh3)2] were prepared from molybdenum hexacarbonyl, sodium borohydride and triphenylphosphine with a % yield of 79% and 8.5% respectively. Two isomer was identified using IR spectra and from isomer A four C≡O stretching was observed, while in isomer B only one C≡O stretching was observed in a frequency ranged of (1867.24- 2024,39 cm-1) and 1880.91 cm-1 through this results isomer A concluded to be cis and B to be trans isomer .

Results discussion

|Isomer A |Isomer B |
| | |
|Isomer A was obtained as a very fine, light yellow, crystalline |Isomer B was obtained as a fine, pale yellow powder. |
|powder. |Mass of Isomer B Produced: 0.0424 g |
|Mass of Isomer A Produced: 1.102 g | |
|Mass of [Mo(CO)6] Used: 0.5000 g |Mo(CO)4(PPh3)2 (Isomer A) → Mo(CO)4(PPh3)2 (Isomer B) |
|n = m/Mr | |
|= 0.5000 g /264.00 g/mol |Since isomer A and B are geometric isomers, the data from isomer A can|
|= 1.893×10-3 mol |be