The Role of the Topology of Spin Density in Metal-Ligand Interactions
and
Comparison between Constrained Theoretical Wavefunctions and Unconstrained Theoretical Wavefunctions

David Ramírez-Palma1a, Fernando Cortés-Guzmán1b, and Julia Contreras-García2
1Instituto de Química, Universidad Nacional Autónoma de México, Ciudad de México, México
adavid.ramp49@gmail.com; bfercor@unam.mx
2Laboratoire de Chimie Théorique, UMR 7616, Paris, France - contreras@lct.jussieu.fr

Mercredi 6 Février 2019, 11h00
bibliothèque LCT, tour 12 - 13, 4ème étage

The Quantum Chemical Topology provides a methodology to obtain relevant chemical information of a scalar field, in this case, the laplacian of the spin density and its components alpha and beta. Here, we analyzed the behavior of the abovementioned scalar fields in hexa-aquo complexes and we described the communication metal - ligands in the complex formation process using the Quantum Theory of Atoms in Molecules [1]. The polarization of the laplacian of electron density depends of its incomplete valence shell. For this reason, the interaction between the metal center and the ligands is governed by the incomplete spin component valence shell. Furthermore, we can link the changes in the laplacian of the electron density with the stabilization of the metal center and changes in attractive and repulsive forces [2].

[Picture]

Figure 1. Laplacian of spin density in the complex [Ni(H2O)6]2+.


On the other hand, Tonto is a software developed by Jayatilaka and Grimwood [3] for chemistry and quantum crystallography. It specializes in the calculation and analysis of wave functions, as well as obtaining crystalline structures and experimental wavefunctions. Here, we use the experimental data of NH3 to compare the X-ray constrained wavefunction (XCW) with unconstrained wavefunctions from solid state (UCW-Cry) and the isolated molecule calculations (UCW-IM).

[Picture]

Figure 2. Difference between the ELF for UCW-Cry and XCW of NH3.
ELF plot with iso-contour value of 0.5 in black.


_________________________________

References :
[1] R. F. W. Bader, Atoms in Molecules: A Quantum Theory, Oxford University Press, Oxford 1990.
[2] L. Gutierrez-Arzaluz, D. I. Ramírez-Palma, L. G. Ramírez-Palma, J. E. Barquera-Lozada, J. Peón, and F. Cortes-Guzman, Chem. Eur. J., 2019 25, 775-784.
[3] D. Jayatilaka and D. G. Grimwood, Computational Science - ICCS 2003, 2003 4, 142-151.