[Controlled Substance]

I'm going to try to keep this as coherent as possible; I am fairly new to chemistry... Please bear with me!

My main problem so far as I have been going through my Gen. Chem. book is that I constantly just have to take their reactions for granted. It just spits out unbalanced equations and supplies me with charts and "rules", without getting into much detail about why reactions are happening.

I'm not having too much fun. What fascinates me most in chemistry are the microscopic details of organic synthesis such as molecular structure and the reasons why reactions occur.

I recently came across a very brief introduction to MO theory, and alas, I think I have found the solution to all my concerns. The detail level of the diagrams really ummm... 'tickled my fancy'.

My questions are:
Assuming I go through the process of learning all the math necessary to understand the reasoning behind MO diagrams, will I be able to better understand reaction mechanisms?
Is it through MO theory that one can derive accurate assumptions about the chemical properties of a compound?

If MO theory, can indeed provide me with the answers I am looking for, what are some books or websites that you strongly recommend?

Thanks in advance.

[movies]

Excellent question!  I am glad that you have found molecular orbitals as a potential explanation for your problems.

Learning the math behind MO theory will help you a lot, but most of it is to derive why you get the particular orbitals that you do.  It is definitely worthwhile to know these things, but you can also get by with some shortcuts.  If you know what the important orbitals look like from experience then you don't have to do the math and you can infer the properties and reactivity of a molecule on-the-fly.  This is what I find really exciting about MO theory, and it sounds like you do too.  You will need a pretty strong background in math to get all of the stuff that goes into calculating orbitals.  At least up through multivariable calculus.

I would recommend that you review your gen chem book and do take the reactions for granted at this point.  Learning the empirical results of reactions will help you once you get a handle on the orbitals.  It's all about reconciling the two approaches.  You will undoubtedly find at some point that you may predict one thing with MO theory but experiment finds another and you will have to go back and find out what you overlooked in the MO theory.  There is a lot going on with MOs!

The book that really helped me with MO theory is called "Frontier Orbitals and Organic Chemical Reactions" by Ian Fleming.  It can be pretty dense to read straight through, and it does assume that you are familiar with some routine organic chemistry, but it is an outstanding book.  There are a lot of web sites out there, but I can't recommend a particular site since I used the book.

I hope this helps.  Good luck!

[Controlled Substance]

Great reply. It did help me very much!

I took a look at the book you recommended to me and it's waaayyy above my level right now 
Seems like it contains some wonderful stuff though! I wrote down the title, thanks...

So if I understand correctly, the math in MO theory can help determine such things as bond energies, and in consequence the reactivity at certain sites in a compound. (EDIT: in combination with factors like formal charges, overall polarity, etc...) Correct?

I can't rest peacefully until I know this  I don't like shortcuts... I really want to be able to visualize the small details.

[movies]

MO theory is an unending journey, so don't be intimidated at this point.  I definitely didn't get it on the first pass.  I don't think that things started to fall into place for me until my first year of grad school, and that was three years after I first saw basic MO theory!

MO theory is about tracking the electrons, for the most part.  Electrons are the big thing for reactions because they make up the bonds.  Most of MO theory is calculating the probability of where the electrons are (you can't know where they are exactly due to the Heisenberg uncertainty principle, or if you can know, you can't tell what they are going to do next).  Beyond that it is a lot of bringing partial positive charges to partial negative charges.  There are some subtle differences in how these can come together, but that is the fascinating part!

Feel free to ask any other questions here.  I will help as much as I can, but I have an organic chemists view of orbitals, not a physical chemists view, so I am probably not the best person to guide you through the math end of things!  If you are looking for a good place to start, I would recommend looking at the MO analysis of the Diels–Alder reaction, since it is one of the most studied.

[Controlled Substance]

Intimidated? Umm... 

This stuff is much more complex than I imagined!

I've been looking into it a lot since your last reply and I only have basic general chemistry knowledge and calculus skills.

Simply by browsing through books online and their tables of contents I learned a tremendous amount of stuff.

I can't wait to recieve this in the mail: http://www.amazon.ca/Chemistry-Maths-Book-Erich-Steiner/dp/0199205353/ref=sr_1_3?ie=UTF8&s=books&qid=1210650456&sr=8-3
I can't believe the price either. It is 60USD+ everywhere else on the net.

It also appears I would need more in-depth knowledge about quantum chemistry before jumping into MO theory. I know you said you didn't have a physical chemist's view, but have you read any books on this worth mentioning?

Organic chem doesn't seem like a priority to me, because after all, from what I understand, the chemical properties of all functional groups and their interactions can be described through quantum chemistry and orbital interactions. Correct me if I am wrong.

[movies]

You are absolutely right that all the effects in organic chemistry can be explained by the MO theory, BUT what I am trying to tell you is that the empirical results come first and then the MO theory comes along and matches it, not the other way around.  It's really two ways of thinking about the same thing, I find it easier to wrap my brain around it one way, you might find it different for you and that is okay too!

I took quantum mechanics when I was an undergraduate and I have to admit it was very hard for me to follow.  I couldn't make the connections between the equations and the physical interpretation; that is to say, I couldn't picture (visually) what the equations were telling me.  For you, I think most any decent physical chemistry book will give you a good overview of the QM that you need to know.  You may want to seek out an expert to try to explain some of the concepts to you as well.  Things get kinda screwy in QM; it's not like normal physics on macroscale.  A physicist or real physical chemist is probably best.

[kryptoniitti]

I agree with movies. It's definately great that you are deeply interested in MO theory and its math, more power to you. Knowledge can never hurt but maybe in this case, learning all the math behind the MO theory for the purpose of reaction mechanisms and organic synthesis seems to me a bit like rube goldberg machine. When you start looking up mechanisms for various reactions in organic chemistry, you'll find plenty of "proposed mechanism", "it is believed that reaction goes like this..." etc. I mean there are lot of material that still can't be explained even with our current knowledge of MOs and QM. For most of time IMHO one can rely on non-mathematical, qualitative "rules of the thumb" taught in organic chemisty textbooks when predicting reaction mechanism. This is just my 0.02$, your experience may vary

[Controlled Substance]

I find it easier to wrap my brain around it one way, you might find it different for you

Yep. I'm a bottom-up learner. I need to be able to understand all lower principles first. Or else I can't remember well.

But my fascination with MO is much deeper now than at the time of my first post. (When it just seemed like a interesting topic.)

I just think it's the most F*$%@#! amazing thing. 

I won't get far into it unless you want to wait for me write an unwritten book...

Actually, I'm not too sure myself why MO appeals to me so much. I know it isn't necessary for me to learn this, but I just wanna BE there at least once.  At the lowest level of our understanding. (Not the lowest, of course, but damn close enough!) Using only pencil, paper, calculator and brain.  Bad ass stuff.

Maybe its just how a complex system of continuously reacting "matter", can have the "intelligence" to come up with "mathematical" models and other systems that enable it to accurately make predictions. With no other "purpose", than to improve its own conditions. With the words in quotes having absolutely no relevance outside consciousness.

Insane.

Welll... I'm gonna force myself to stop here. It is very hard to explain.