Research Interests

A Bit of History: Colin's early research involved studies of the chemistry of free carbon atoms. This led to an interest in carbon suboxide, C3O2, which, when irradiated with deep ultraviolet radiation produces free carbon atoms. However, it is also a source of both singlet and triplet carbonyl carbenes, C2O. With simple molecules these act as carbon atom donors to give allenes with the overall stoichiometry being

C2O + H2C=CH2 -> H2C=C=CH2 + CO

With more complex molecules Haverford students have shown that they give the C2O-H2C=CH2 adduct which then dimerizes.

As a result of being a graduate student at the U. of Chicago when Stanley Miller was doing his classic work on the production of amino acids from primitive earth atmospheres Colin and his students have also worked on trying to trace out the path by which these are formed.

 

Recent Research: More recently Colin and his students have been investigating the reaction of triplet C2O with fluorinated and chlorinated olefins. The relative reactivities of this carbene with the series of molecules CHyX4-y, where X can be either F or Cl, and y can vary from 4 to 0 are unusual. If you would like to see the plot of the fluorocarbon data click here. If you would like to see a plot of the chlorocarbon data click here.

We had expected a monotonic change and were unable to explain this pattern satisfactorily. However, more recently a student, Daniel Freese, succeeded in qualitatively reproducing the fluorocarbon pattern using a semi-empirical quantum mechanical program, and building on his work we have qualitatively reproduced the chlorocarbon pattern. So far we have not been able to work at a sophisticated enough level of ab initiio theory to even reproduce the pattern qualitatively.

Freese's calculations predicted that triplet CH2 would show the same pattern with the fluorocarbons. Currently we are testing this experimentally and the early evidence is that the prediction is born out.

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