Substituent-induced perturbation symmetries and distortions of meso-tert-butylporphyrins
- Sandia National Labs., Albuquerque, NM (United States). Materials Theory and Computation Dept.
- Sandia National Lab., Albuquerque, NM (United States). Materials Theory and Computation Dept.
The out-of-plane and in-plane distortions of a series of nickel(II) meso-substituted porphyrins with 0, 1, 2, or 4 tert-butyl groups [nickel(II) porphine (NiP), nickel(II) mono-tert-butylporphyrin (NiMtBuP), nickel(II) di-tert-butylporphyrin (NiDtBuP), and nickel(II) tetra-tert-butylporphyrin (NiTtBuP)] are investigated using molecular mechanics (MM) calculations, X-ray crystallography, UV-visible absorption spectroscopy, and resonance Raman spectroscopy. MM calculations are used to predict the stable conformations for this series of porphyrins. The out-of-plane distortions are then analyzed in terms of displacements along the normal coordinates of the porphyrin macrocycle using a new normal-coordinate structural decomposition method. Detailed analysis of the types of distortion revealed that both the out-of-plane and the in-plane distortions depend on the perturbation symmetry of the peripheral substituents. Often the perturbation symmetry can be predicted for a given porphyrin simply from the possible orientations of the substituents. The stable conformers predicted by MM for the series of tert-butyl-substituted porphyrins confirm this simple but informative approach. Experimental verification of the calculated contributions of the symmetric deformations is provided by normal-coordinate structural decomposition of the available X-ray crystal structures of NiP, NiMtBuP, and NiDtBuP. The solid-state results are also supported by the resonance Raman and UV-visible absorption spectroscopic characterization of the porphyrins in solutions. The X-ray crystal structure of NiMtBuP is reported here for the first time.
- Research Organization:
- Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 642382
- Journal Information:
- Inorganic Chemistry, Vol. 37, Issue 9; Other Information: PBD: 4 May 1998
- Country of Publication:
- United States
- Language:
- English
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