Quantum-Chemistry Centered Normal Coordinate Analysis (QCC-NCA)

Model [Fe(P)(MI)(NO)] has only C1 symmetry and hence, about 18000 individual force constants

This is impossible to solve for conventional Normal Coordinate Analysis (NCA)

QCC-NCA: use DFT calculated force field as initial guess

Subdivide system into core (Fe-NO unit) and frame (porphyrin, MI)

Refine only selected force constants to reproduce the vibrations of the core

We have developed software to routinely perform these calculations

N. Lehnert, F. Tuczek
"The Reduction Pathway of End-on Coordinated Dinitrogen: I. Vibrational Properties of Mo/W-N2, -NNH and -NNH2 Complexes and Quantum Chemistry Assisted Normal Coordinate Analysis"
Inorg. Chem. 1999, 38, 1659-1670

V. K. K. Praneeth, C. Näther, G. Peters, N. Lehnert
"Spectroscopic Properties and Electronic Structure of Five- and Six-Coordinate Iron(II)-Porphyrin NO Complexes: Effect of the axial N-Donor Ligand"
Inorg. Chem. 2006, 45, 2795-2811

F. Paulat, T. C. Berto, S. DeBeer George, L. Goodrich, V. K. K. Praneeth, C. D. Sulok, N. Lehnert
"The Vibrational Assignments of Six-Coordinate Ferrous Heme Nitrosyls: New Insight from Nuclear Resonance Vibrational Spectroscopy"
Inorg. Chem. 2008, 47, 11449-11451

N. Lehnert, M. G. I. Galinato, F. Paulat, G. B. Richter-Addo, W. Sturhahn, N. Xu, J. Zhao
"Nuclear Resonance Vibrational Spectroscopy applied to [Fe(OEP)(NO)]: the Vibrational Assignments of Five-Coordinate Ferrous Heme Nitrosyls and Implications for Electronic Structure"
Inorg. Chem. 2010, 49, 4133-4148

N. Lehnert, J. T. Sage, N. Silvernail, W. R. Scheidt, E. E. Alp, W. Sturhahn, J. Zhao
"Oriented Single-Crystal Nuclear Resonance Vibrational Spectroscopy of [Fe(TPP)(MI)(NO)]: Quantitative Assessment of the trans Effect of NO"
Inorg. Chem. 2010, 49, 7197-7215