[beheada]

For both problems, I am drawing the reaction via structures and using curved arrows for electron flow.

1) If given OCH₂ + ^-CN --> OCH₂CN. I need to draw the actual structures as they happen in the reaction, but I started thinking to myself... why is the cyanide ion negative overall, or is it? A triple bonded N's overall charge is (5-0-6/2=+2) which would make it largely positive. The carbon has a negative charge (4-2-6/2=-1). Now I understand why the carbon goes after the other carbon due to partial electronegativity and what not, but what I don't understand is why my professor has the Cyanide ion labeled as an overall negative ion?! I looked on Wikipedia and it also says the ion is negative, so I'm trying to figure out why? If Nitrogen is positive and larger than the Carbon... why the negative charge?

2) I have another reaction, same type of problem... very simple.

H + F₂ --> HF + F

In drawing it... does the H have a free radical electron, or will it have 2 valence electrons? One of the Fluorine's should go after the H and grab it, but if there's a radical, then I'm not sure what happens. If there were two valence electrons then I'm sure the one Fluorine would grab the H, and then the bond between the two Fs would swap over to the one F and make a free F ion. And why hasn't he labeled the second Fluorine with a negative charge if it takes the electrons from the broken bond? Is this correct?




Lastly... I've been reading about different research interests of professors at my university and stumbled upon one doing research into organic substrates used for photovoltaic cells and some other things like organic LEDs, etc. I was wondering if this type of research involves a background with electronics, like say needing a minor in electrical engineering or something? It sounds like the type of work I'd like to get involved in, but I haven't had a chance to talk to this professor yet because he's extremely busy. Does anyone here know of a minor or another major that would help, since it seems there will be some type of emphasis on electronics?

[Dan]

1) If given OCH₂ + ^-CN --> OCH₂CN. I need to draw the actual structures as they happen in the reaction, but I started thinking to myself... why is the cyanide ion negative overall, or is it?

Firstly, don't forget the basics. Charges must balance on both sides of the reaction, your product is wrong, it should be ^-OCH₂CN
Cyanide ion is negatively charged because there is an excess of one electron over protons in the ion.

.C:::N: would be neutral (and a radical)

:C:::N: is negatievely charged

2) I have another reaction, same type of problem... very simple.

H + F₂ --> HF + F

In drawing it... does the H have a free radical electron, or will it have 2 valence electrons? One of the Fluorine's should go after the H and grab it, but if there's a radical, then I'm not sure what happens. If there were two valence electrons then I'm sure the one Fluorine would grab the H, and then the bond between the two Fs would swap over to the one F and make a free F ion. And why hasn't he labeled the second Fluorine with a negative charge if it takes the electrons from the broken bond? Is this correct?

This reaction involves the H radical, and one of the products is the F radical. Remember to use half arrows (sometimes called fish hook arrows) for the mechanism.
If H has 2 electrons, it is H^-, since H only has one proton.

[beheada]

Woops! I accidentally wrote the product wrong, but I do have the negative charge on the Oxygen there. The reason I was confused on the cyanide ion was the fact that wikipedia's little drawing leaves off the lone pair of nitrogen, which I figured was the case.

For the second problem... this is what I figured out. Since he has the whole thing written with no charges on it, and H is neutral at 1, that means it has a radical. F is neutral at 7, which means there needs to be a homolytic break at the F-F bond. So... the one F grabs the hydrogen and they form a bond, and the other F is left with 7 electrons and no charge?

I have the one sided arrows drawn from the F-F bond to each Fluorine and then one arrow drawn from the left F to the Hydrogen? Is that the proper/correct way to draw this reaction as it happens?

[Dan]

I have the one sided arrows drawn from the F-F bond to each Fluorine and then one arrow drawn from the left F to the Hydrogen? Is that the proper/correct way to draw this reaction as it happens?

Sounds fine, I think  (but I'm not claiming to be an expert) that the reaction would be concerted (ie one step, have all those arrows there in a single diagram). It would also be acceptable to draw a single half arrow from the F-F bond to the H radical.

Just to clarify,

H + FF ----> HF + F

rather than

H + FF ----> H + F + F ----> HF + F

if you see what I mean...