23 Apr 2012

Five Slides About Percent Buried Volume (%Vbur)

Five Slides About

Submitted by Chip Nataro, Lafayette College

These slides present a walkthough of performing a Percent Buried Volume (%Vbur) calculation. The %Vbur is a measurement of the bulk of a ligand coordinated to a transiton metal. The calculation uses the crystal structure of a compound to determine how much space a ligand occupies. It does this by placing the metal at the center of a sphere and then calculates the volume of that sphere occupied by the ligand. Originally developed for N-heterocyclic carbene (NHC) ligands, it has also been applied to mono- and bidentate phosphines.

Learning Goals: 

This presentation was a step-by-step guide to performing a %Vbur calculation using a crystal structure from the literature. With the newer graphical version of the site that information is no longer useful. However, the 5 slides should give you the backgrounded needed to understand what this calculation is all about.

Evaluation Methods: 

The SambVca software will either report a %Vbur value or it will not. The value will only be reported if the data is in the correct format and if the proper information is input. The recommendation would be to try the calculation of some of the Au(PR3)Cl compounds reported by Nolan to determine if calculation has been mastered.

Evaluation Results: 

One honor's thesis student has been successful at calculating %Vbur values.

Creative Commons License: 
Creative Commons Licence



This looks like a very useful concept that I had not seen before.  One procedural note that I missed on my first viewing: there are movies embedded in the pptx file (the same movies that are attached as the zip file). I only saw the black screen and was wondering what the problem is.

I teach Tolman cone angle as a method for thinking about sterics but the %Vbur seems like a much more meaningful (albeit harder to calculate) number. I can see myself using this for my own ligands in my research as well as in my teaching.


Following up on Adam's concept, I wondered if anyone had connected cone angles with %Vbur in some meaningful comparison?


The site has recently been upgraded to version 2.0. Usually I am resistant to change but in this case I can say without a doubt it made a huge difference! It is now all graphical. And even better, it includes a library which you can use to see exactly how to go about doing these calculations. I am have modified the 5 slides to keep some of the background information. I am not going to update any of the info on how to do the calculations because the site provides you with that info now. I liked these calculations before, I love them now.

I have tried to log into the website provided here and in the paper and it won't let me access it. 


I keep getting notifications such as: 

"The site cannot be reached" or "refused to connect"

Was the site developed for a particular type of computer (Mac or PC), or for a particular internet browser?

I haven't seen any retraction or modification of the original or 2016 paper so I was wondering why I could not connect. Has anyone else had these issues?

Thank you for the help.




Hi Joshua,

Nope it seems the site is down. I will contact Luigi to see what is happening.

Just heard back from Luigi, their server crashed. They hope to have the site back up in a few days.

Thank you very much,


I can't wait to use it!



I just heard back from Luigi, the server is back online. Good luck!

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