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Disproportionation Reaction Lab Report

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18e rule is the most stable product from disproportionation reaction. In this experiment to study about 19-electron intermediate reactivity and mechanism of disproportionation reaction of [CpW(CO)3]2 in solvent cage effect varied of Lewis bases. Disproportionation reaction of [CpW(CO)3]2 was activated by photolysis reaction at 400 nm separate to two radical of 17e (CpW(CO)3•), then add Lewis base will generate radical of 17e to 17e/19e radical in solvent cage effect. in solvent cage electron transfer to 17e, disproportionated product was separated in cationic and anionic formation. In this reaction ultrafast time scale using femtosecond VIS-pump, IR-probe spectroscopy. Lewis bases is using is P(OMe)3 , PBu3 and PPh3 that has …show more content…

High concentration 17e/19e intermediate has electron transfer in cage radical pair and go to disproportionated product CpW(CO)3- and CpW(CO)3P(OMe)+ is 18e. In low concentration case, radical may slowly electron transfer. The sepation of radical equivalent to breakdown the solvent cage. Reaction between PBu3 likely reaction with P(OMe)3. Kinetic in this reaction slightly faster than P(OMe)3. Kinetic was indicate by using decay of 17e to formation 19e intermediate(high concentration) and separation of cage radical pair(low concentration). Reaction with PPh3 has result different from two lewis base. In this case if compare between 17e radical from electron transfer to disproportionated product and 17e/19e equilibrium this reaction likely to 17e/19e in equilibrium and product of 19e intermediate outside solvent cage to two species of radica Because 19e intermediate CpW(CO)3PPh3• is less stable than others. And kinetic in this reaction has longer time to go to equilibrium and may be react out of …show more content…

Trend of reduction potential is P(OMe)3 (-0.1344 v ) > PPh3 (-0.2630 V) > PBu3 (-0.3990 V) , electron donating ability : PBu3 (2060.3 /cm) > PPh3 (2068.9 /cm) > P(OMe)3 (2079.5 /cm) that lower frequency is better electron donating. And cone angle of Lewis bases molecule in order to PPh3 (145) > PBu3 (132) > P(OMe)3 (107). This properties will explain about from 17e to 19e intermediated is different experimental data in PPh3. PPh3 has cone angle more than others lewis base steric effect dominate hinder to form intermediate with 17e to 19e intermediated, that make 17e with PPh3 favoring to 17e/19e equilibrium more than in radical pair cage and to disproportionated

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