Synthesis of Vaska's Complex

[carolp1290]

Hello all,

 

I'm in organometallic chem right now, and this question is on our new problem set:

 

The rxn of IrCl3 with EtOH produces trans-Ir(PPh3)2(CO)Cl aka Vaska's copmlex along with 2HCL and CH4. When isotopically labeled ethanol is used (CH3CH2OH), the carbonyl ligand is fully enriched in 13-C. Provide a mechanism. Do not worry about the degree of solvation or PPh3 coordination at each step.

 

IrCl3 + 2 PPh3 ---Ethanol---> Vaska's Complex

 

I talked to my professor this afternoon, and he was somewhat helpful, but I'm still having problems. He said to remember that the starting Ir complex dissociates in polar solvent, so there would be constant ligand exchange (thus the "don't worry about PPh3 coordination"). This is some sort of solvolysis, but I can't figure out how. I think the mechanism is something involving reductive elimination.

 

Please help if you can!

[Charlatan]

Hello all,

 

I'm in organometallic chem right now, and this question is on our new problem set:

 

The rxn of IrCl3 with EtOH produces trans-Ir(PPh3)2(CO)Cl aka Vaska's copmlex along with 2HCL and CH4. When isotopically labeled ethanol is used (CH3CH2OH), the carbonyl ligand is fully enriched in 13-C. Provide a mechanism. Do not worry about the degree of solvation or PPh3 coordination at each step.

 

IrCl3 + 2 PPh3 ---Ethanol---> Vaska's Complex

 

I talked to my professor this afternoon, and he was somewhat helpful, but I'm still having problems. He said to remember that the starting Ir complex dissociates in polar solvent, so there would be constant ligand exchange (thus the "don't worry about PPh3 coordination"). This is some sort of solvolysis, but I can't figure out how. I think the mechanism is something involving reductive elimination.

 

Please help if you can!

 

The rxn of IrCl3 with EtOH produces trans-Ir(PPh3)2(CO)Cl aka Vaska's copmlex along with 2HCL and CH4. When isotopically labeled ethanol is used (CH3CH2OH), the carbonyl ligand is fully enriched in 13-C. Provide a mechanism. Do not worry about the degree of solvation or PPh3 coordination at each step.

 

IrCl3 + 2 PPh3 ---Ethanol---> Vaska's Complex

 

So here we have a problem. Let's look into my crystal ball for a moment...

 

OK, so you want to solve vaska's complex eh??? You want to make little yellow things then? My my my, what ambition!

 

So, if you want to add ethanol to something, it is actually a fossil fuel, being a melted solid. If you want to add petroleum to the things you know about, it will all get 'oiled'. Oil is a corrupting substance - it bonds with the liquids and gets basically inside them. It also goes to the bottom of the substance, so is heavier. It lightly covers the upper parts of the liquid as the carbon density there is less, so it wil be displaced there.

 

Ok, so you heard the rhetoric, now you want to know how and why, yes?

 

I guess you want to know how and why. It bonds because the liquid is quite dense, so the oil doesn;t go to the bottom. It goes yellow because it is a mixture os oil, which is black, and white liquid. What happens when you mix silver and black? Well it depends how much oil there is! But that isn't the question is it???

 

They bond because they are the same weight, and it only looks like they bond. This is a typical mixture, you can add all the fancy symbols you want, but the answer is that they are the same weight or carbon density. This is content based answer, unfortunatley, and there is no need for a hypothesis, yes? Write my answer on your papaer and see them say it is wrong, remember you get full marks for the answer, and the answer must make sense.

 

Vask's useless rubbish is more like it...

[carolp1290]

Thank you for your help, but what I actually need is more of a step-by-step description of the reactions which produce Vaska's complex. Like, it undergoes ligand substitution, insertion, reductive elimination, etc. Any other suggestions?

[Charlatan]

Thank you for your help, but what I actually need is more of a step-by-step description of the reactions which produce Vaska's complex. Like, it undergoes ligand substitution, insertion, reductive elimination, etc. Any other suggestions?

 

Well, funny you should ask, let me suck my thumb some more to make mo answers without using old answers...

 

There is no substituion of the ligand thing, because then the cell would change into a ligand stuffs. Insertion doesn't help because if you insert some stuffies into it then it will change to be a compound that is not what it is, catch my drift?

 

reductive elimination occurs because living things go dead like! Beounos nachos, assif, awaad wa bikheyr lui', min faDlik...