Distortion parameters¶

Mathematical expression of the octahedral distortion parameters are given by following equations

• $$\zeta$$ parameter [1]
$\zeta = \sum_{i=1}^{6}\left | d_{i} - d_{mean} \right |$

where $$d_{i}$$ is individual M-X bond distance and $$d_{mean}$$ is mean metal-ligand bond distance.

• $$\Delta$$ parameter [2]
$\Delta = \frac{1}{6} \sum_{i=1}^{6}(\frac{d_{i} - d_{mean}}{d_{mean}})^2$

where $$d_{i}$$ is individual M-X bond distance and $$d_{mean}$$ is mean metal-ligand bond distance.

• $$\Sigma$$ parameter [3]
$\Sigma = \sum_{i=1}^{12}\left | 90 - \phi_{i} \right |$

where $$\phi_{i}$$ in individual cis angle.

• $$\Theta$$ parameter [4]
$\Theta = \sum_{i=1}^{24}\left | 60 - \theta_{i} \right |$

where $$\theta_{i}$$ is individual angle between two vectors of two twisting face.

 [1] M. Buron-Le Cointe, J. Hébert, C. Baldé, N. Moisan, L. Toupet, P. Guionneau, J. F. Létard, E. Freysz, H. Cailleau, and E. Collet. - Intermolecular control of thermoswitching and photoswitching phenomena in two spin-crossover polymorphs. Phys. Rev. B 85, 064114.
 [2] M. W. Lufaso and P. M. Woodward. - Jahn–Teller distortions, cation ordering and octahedral tilting in perovskites. Acta Cryst. (2004). B60, 10-20. DOI: 10.1107/S0108768103026661
 [3] J. K. McCusker, A. L. Rheingold, D. N. Hendrickson. Variable-Temperature Studies of Laser-Initiated 5T2 → 1A1 Intersystem Crossing in Spin-Crossover Complexes: Empirical Correlations between Activation Parameters and Ligand Structure in a Series of Polypyridyl. Ferrous Complexes. Inorg. Chem. 1996, 35, 2100.
 [4] M. Marchivie, P. Guionneau, J.-F. Létard, D. Chasseau. Photo‐induced spin‐transition: the role of the iron(II) environment distortion. Acta Crystal-logr. Sect. B Struct. Sci. 2005, 61, 25.