Computational studies of molecular electronic structure
My research efforts focus on computational investigations of molecular electronic structure using ab initio and semiempirical molecular orbital techniques.
Ab initio calculation of the catalytic activation of C-H and C-F bonds by transition metals
In a DOE-funded collaboration with Professor Alan Goldman and his research group, we are using ab initio electronic structure methods to calculate thermodynamic and kinetic parameters pertaining to a number of fundamental catalytic reactions involving transition metal complexes and small molecule substrates. We are especially interested in C-X (X = H, F) bond breaking processes and in the study of oxygen atom transfer reactions. Also of interest is the accurate computation of kinetic and thermodynamic isotope effects for organometallic reactions. We hope to make such calculations into almost a "routine" tool and to provide detailed mechanistic interpretations of isotope effects for a number of prototypical - and some perhaps not so prototypical - reactions.
Semiempirical electronic structure calculations on large systems
We use semiempirical all-valence electron methods for studies of electronically excited states of large molecules. We are currently investigating a number of dimeric systems related to photosynthetic reaction centers and also some small molecular aggregates of potential interest to photovoltaic cell design. Finally, the merger of molecular orbital techniques with classical molecular mechanics/dynamics techniques for the purpose of investigating the ground and excited state properties of molecules imbedded in a condensed phase such as water or protein continue to be of interest.
I have, for a number of years, mostly been involved in the teaching of General Chemistry. However, I have just returned to delivering one of my favorite courses, the introductory course in quantum chemistry for graduate students (and senior undergraduates). I am having particular fun with a number of computational assignments in this course — for additional details about this project, look at: Atomic and Molecular Structure: Chemistry 421/521
D. Laviska, C. Guan, T. J. Emge, M. Wilklow-Marnell, W. M. Brennessel, W. D. Jones, K. Krogh-Jespersen, and A. S. Goldman, "Addition of C-C and C-H Bonds by Pincer-Iridium Complexes: a Combined Experimental and Computational Study", Dalton Trans., 43, 16354-16365 (2014).
R. A. Moss, L. Wang, and K. Krogh-Jespersen, "Dependence of activation parameters for phenylchlorocarbene-alkene additions on alkane solvent chain length", Tetrahedron Lett., 55, 6016-6018 (2014).
P. Hoijemberg, R. A. Moss, D. V. Feinblum, and K. Krogh-Jespersen, "O-Ylide and π-Complex Formation in Reactions of a Carbene with Dibenzo and Monobenzo Crown Ethers", J. Phys. Chem. A, 118, 6231-6238 (2014).
R. A. Moss, H. Cang, and K. Krogh-Jespersen, "The nucleophilicity of adamantanylidene: a Hammett study", Tetrahedron Lett., 55, 4278-4280, (2014).
J. D. Hackenberg, S. Kundu, T. J. Emge, K. Krogh-Jespersen, and A. S. Goldman, "Acid-Catalyzed Oxidative Addition of a C-H Bond to a Square Planar d8 Iridium Complex", J. Am. Chem. Soc., 136, 8891-8894 (2014).
C. Cheng, B. G. Kim, D. Guironnet, M. Brookhart, C. Guan, D. Y. Wang, K. Krogh-Jespersen, and A. S. Goldman, "Synthesis and Characterization of Carbazolide-based Iridium PNP Pincer Complexes. Mechanistic and Computational Investigation of Alkene Hydrogenation: Evidence for an Ir(III)/Ir(V)/Ir(III) Catalytic Cycle", J. Am. Chem. Soc. 136, 6672-6683 (2014).
Q. Cao, G. Gor, K. Krogh-Jespersen, and L. Khriachtchev, "Non-Covalent Interactions of Nitrous Oxide with Aromatic Compounds: Spectroscopic and Computational Evidence for the Formation of 1:1 Complexes", J. Chem. Phys., 140, 144304 (2014).
R. A. Moss, L. Wang, and K. Krogh-Jespersen, "The Nucleophilicity of a Dialkylcarbene: Unusual Activation Parameters for Additions of Adamantanylidene to Simple Alkenes", J. Am. Chem. Soc., 136, 4885-4888 (2014).
R. A. Moss, L. Wang, P. A. Hoijemberg, and K. Krogh-Jespersen, "Visualizing Carbene Equilibria", Photochem. Photobiol. A: Chem., 90, 287-293 (2014) (Invited Review; also featured as a Highlight paper).
J. Hackenberg, K. Krogh Jespersen, and A. S. Goldman, "Activation of C-O and C-F Bonds by Pincer-iridium Complexes", pp. 39-58 in "Advances in Organometallic Chemistry and Catalysis: The Silver/Gold Jubilee International Conference on Organometallic Chemistry Celebratory Book," A. J. L. Pombeiro, Ed.; John Wiley & Sons, Hoboken, NJ (2013).
R. A. Moss, L. Wang, and K. Krogh-Jespersen, "The Reactivity of Chlorotrifluoromethylcarbene: Activation Parameters for Halocarbene-Alkene Addition Reactions", J. Org. Chem., 78, 11040-11044 (2013). http://dx.doi.org/10.1021/jo402058k
M. C. Haibach, C. Guan, D. Y. Wang, B. Li, N. Lease, A. Steffens, K. Krogh-Jespersen, and A. S. Goldman, "Olefin Hydroaryloxylation Catalyzed by Pincer Iridium Complexes", J. Am. Chem. Soc., 135, 15062-15070 (2013). http://dx.doi.org/10.1021/ja404566v
M. C. Haibach, D. Y. Wang, T. J. Emge, K. Krogh-Jespersen, and A. S. Goldman, "(POP)Rh Pincer Hydride Complexes: Unusual Reactivity and Selectivity in Oxidative Addition and Olefin Insertion Reactions", Chem. Sci., 4, 3683-3692 (2013).
R. A. Moss and K. Krogh-Jespersen, "Carbenic philicity and the "intrinsic reactivity index" Tetrahedron Lett., 54, 4303-4305 (2013).
L. Wang, R. A. Moss, and K. Krogh-Jespersen, "Hammett Analysis of Halocarbene-Halocarbanion Equilibria" Org. Lett. 15, 2014-2017 (2013)
S. Kundu, J. Choi, Y. Choliy, T. J. Emge, K. Krogh-Jespersen, and A. S. Goldman, "Oxidative Addition of Ether, Ester and Tosylate C(sp3)-O Bonds to an Iridium Complex, Initiated by Oxidative Addition of C-H Bonds. Experimental and Computational Studies", J. Am. Chem. Soc., 135, 5127-5143 (2013).
L. Wang, R. A. Moss, and K. Krogh-Jespersen, "Directly Observed Halocarbene – Halocarbanion Equilibration" J. Am. Chem. Soc., 134, 17459-17461 (2012).
S. Biswas, Z. Huang, Y. Choliy, D. Y. Wang, M. Brookhart, K. Krogh-Jespersen, and A. S. Goldman, "Olefin Isomerization by Iridium Pincer Catalysts. Experimental Evidence for an η3-Allyl Pathway and an Unconventional Mechanism Predicted by DFT Calculations", J. Am. Chem. Soc., 134, 13276-13295 (2012).
F. Hasanayn, P. Achord, P. Braunstein, H. J. Magnier, K. Krogh-Jespersen, and A.S. Goldman, "Theoretical Structure-Reactivity Study of Ethylene Insertion into Nickel-Alkyl Bonds. A Kinetically Significant and Unanticipated Role of trans Influence in Determining Agostic Bond Strengths", Organometallics, 31, 4680-4692 (2012).
P. Hoijemberg, R. A. Moss, and K. Krogh-Jespersen, "Solvent Polarity Effects on Carbene/Ether-O-Ylide Equilibria", J. Phys. Chem. A, 116, 4745-4750 (2012).