Quantum Chemical Studies on The Prediction of Structures ...

Quantum Chemical Studies on The Prediction of Structures ...

QUANTUM CHEMICAL STUDIES ON THE PREDICTION OF STRUCTURES, CHARGE DISTRIBUTIONS AND VIBRATIONAL SPECTRA OF SOME Ni(II), Zn(II), AND Cd(II) IODIDE COMPLEXES Tayyibe Bardak, Mustafa Kumru, and Ahmet Altun stanbul/Turkey International Symposium on Molecular Spectroscopy

71ST MEETING - JUNE 20-24, 2016 - CHAMPAIGN-URBANA, ILLINOIS Outline Introduction Computations Results Molecular Structures Mulliken, NBO and APT Charge Analysis Vibrational Analysis

Conclusion Introduction In this study; ntroduction

Why anilines? Aniline and its derivatives are widely used in: electro-optical and microelectronic devices such as diodes and transistors, intermediate in the production of dyes, pharmaceuticals, ligands in coordination chemistry. Introduction

Why transition metal complexes? A transition metal complex consists of a transition metal coordinated to one or more ligands. Good in catalysis, materials synthesis, photochemistry, and biological systems. Display diverse chemical, optical and magnetic properties. Effective in combining with other elements.

Introductio n Complex Geometries Computations Quantum chemical calculations were carried out with Gaussian 03 software package on our linux server cluster.

The structures and normal modes were visualized by Gausview. Calculations were performed in the gas phase at B3LYP/def2-TZVP level. Def2-TZVP basis set was downloaded from EMSL Basis Set Library, and used with GEN keyword in Gaussian 03. Effective core potentials (ECP) were used within the def2-TZVP. 1. Molecular Structures 2. Mulliken, NBO and APT Charge Analysis

3. Vibrational Analysis Results Molecular structures of the free ligands Mean absolute errors (MAE) and linear correlation coefficient (R2) values:

Bond lengths: 0.015 and 0.984 for p-toludine & 0.016 and 0.983 for m-toluidine. Bond angles: 1.164 and 0.926 for p-toluidine & 1.300 and 0.913 for m-toluidine. Results Molecular structures of the metal iodide complexes of p-toluidine

Distorted tetrahedral Distorted polymeric octahedral Results Some geometry parameters of the metal iodide complexes of p-toluidine

B3LYP/def2-TZVP level predicts: C-N bond length in free p-toluidine: 1.397 H-N-H angle in free p-toluidine: 111.9o Results Molecular structures of the metal iodide complexes of m-toluidine

Distorted polymeric octahedral Distorted tetrahedral Results Some geometry parameters of the metal iodide

complexes of m-toluidine B3LYP/def2-TZVP level predicts: C-N bond length in free m-toluidine: 1.394 H-N-H angle in free m-toluidine: 112.2o Resul ts

Charge Distributions Mulliken, natural bond orbital (NBO), and atomic polar tensor (APT) charge analyses are performed for all compounds. Mulliken is one of the traditional and most widely used methods. But, it is basis set dependent and thus have weaknesses in predicting inaccurate results at some basis sets. Natural charges provided by the NBO method are based on the investigation of the atomic and molecular orbitals and mostly give good results, having no basis set dependency. APT charges are based on the parametrization of the experimental infrared intensities, and

can be directly obtained from default vibrational frequency calculations. If the observed infrared frequencies are consistent with the computed frequencies, mostly APT charge results are also accurate. Resul ts Charge distribution of the free ligands

In free ligands, charge distributions are mostly in agreement with three of the methods, having small differences. Resul Charge distribution of the Ni(II) iodide complexes of pts toluidine and m-toluidine Resul

Charge distribution of the Cd(II) iodide complexes of pts toluidine and m-toluidine Resul ts Charge distribution of the Zn(II) iodide complexes of p-toluidine and mtoluidine Result

s Charge Results In our previous studies, we have also calculated some metal bromide complexes. Different from the metal bromide complexes, we have obtained inaccurate results for charge distributions of metal iodide complexes in the NBO analysis. The reason for this may be iodine is heavier than bromine, and located in the lower part of the periodic table having large number of core electrons. Since

effective core potential (ECP) is used for the iodine containing systems at def2-TZVP level, it may be affected our natural charge distribution results negatively. Results VIBRATIONAL FREQUENCIES As an evidence of complex formation between metal halides and ligands some modes originating from ligand show substantial shifts in the spectra of

complexes. Amino group frequencies of the ligands are generally more affected from the coordination, which shows the complex formation occurs via nitrogen atom of the free ligand. Results Vibrational Frequencies of the Metal Iodide Complexes of P-toluidine

Results Vibrational Frequencies of the Metal Iodide Complexes of M-toluidine Conclusions 1. Molecular Structures Zinc and cadmium complexes are found to have distorted

tetrahedral structures. Nickel complexes have octahedral coordination around the Ni atom, by sharing two I atoms of the neighboring complexes. Conclusions 2. Charge Analysis NBO results are not reliable for our metal iodide complexes.

In terms of having physically most meaningful results, APT method is more trustworthy by showing the most positive charges on metal atoms, and the most negative charges on the nitrogen atoms and halogens. Conclusions 3. Vibrational Analysis As an evidence of complex formation between metal (II) halides and the ligands, amino group frequencies shift lower or higher wavenumbers, which

show coordination occurs via nitrogen atom of the free ligands. In the vibrational spectra of experimental only studies some assignments were not determined correctly. However, we provide a full vibrational assignment of the title complexes for the first time, by means of density functional calculations. Density functional theory finds a good compromise in terms of accuracy and the computational cost. However, for the vibrational frequencies the results might be better, especially above 1700 cm-1.

The development of the new functionals and basis sets for the transition metal complexes is essential as well as providing background information for different systems with the available functionals and basis sets. The results of the present study will be able to serve as a reference for future theoretical studies, which allows molecular dynamics simulation of transition metal complexes or transition metal based drugs. Our Related Articles Tayyibe Bardak, Mustafa Kumru, Ahmet Altun, Molecular structures, charge distributions, and vibrational

analyses of the tetracoordinate Cu(II), Zn(II), Cd(II), and Hg(II) bromide complexes of p-toluidine investigated by density functional theory in comparison with experiments., Journal of Molecular Structure, Vol. 1116, pp. 292-302, 2016. Tayyibe Bardak, Ahmet Altun, Kurtulu Glck, Mustafa Kumru Synthesis, structural, spectral (FT-IR, FT-Ra and UV-Vis), thermal and density functional studies on p-methylaniline complexes of Mn(II), Co(II), and Ni(II) bromides, Journal of Molecular Structure, Vol. 1100, pp.475-485, 2015. Mustafa Kumru, Tayyibe Bardak, Sadk Gner, "DFT calculations and experimental FT-IR, dispersive-Raman and EPR spectral studies of Copper (II) chloride complex with 3-amino-1-methylbenzene", Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Vol. 123, pp.187-193, 2014.

Tayyibe Bardak, Mustafa Kumru, Sadk Gner, "Molecular structure, vibrational and EPR spectra of Cu(II) chloride complex of 4-amino-1-methylbenzene combined with quantum chemical calculations", Journal of Molecular Structure, Vol. 1054-1055, pp.76-82, 2013. Thank You! Source: http://www.sae.edu/tur/tr/campuses/istanbul stanbul/Turkey

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