A DFT study concerning Van der Waals driven Self /Hetero-association reactions of [PtII(1,10-Phenanthroline)(N-pyrrolidyl-N-(2,2- dimethyl-propanoyl)thiourea)]+ and Fluoranthene

Date
2019-12
Journal Title
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Publisher
Stellenbosch : Stellenbosch University
Abstract
ENGLISH ABSTRACT: The self-association of Fluoranthene (reaction 1), hetero-association of [PtII(1,10-Phenanthroline)(N -pyrrolidyl-N-(2,2-dimethyl-propanoyl)thiourea)]+ and Fluoranthene (reaction 2), and the self-association of [PtII(1,10-Phenanthroline)(N -pyrrolidyl-N-(2,2-dimethylpropanoyl) thiourea)]+ (reaction 3) were computationally investigated via Density Func tional Theory. Due to the non-covalent character of all three reactions two strategies where implemented to in an attempt to identify conformational preference prior to geometry optimisation. Firstly, the inter-molecular potential energy surface for reaction 1 and 2 were generated. From these potential energy surfaces six Fluoranthene dimers and three [PtII(1,10-Phenanthroline)(N -pyrrolidyl-N-(2,2-dimethyl-propanoyl)thiourea)]+ · · · Fluoranthene adducts were found. Due to the presence of non-planar aliphatic moieties connected to the thiourea ligand, no inter-molecular potential energy surface could be generated for reaction 3. Rather, a novel Inter Fragment Nearest Neighbour technique was developed, which was found to produce good initial pre-optimised geometry estimates for all three reactions. Dispersion was found to be the dominant stabilising nett interaction energy contribution in all three reactions. The electrostatic interaction energy contribution was found to be stabilising in reactions 1 and 2, and destabilising in reaction 3. The self-association reaction of [PtII(1,10-Phenanthroline)(N -pyrrolidyl-N-(2,2-dimethyl-propanoyl)thiourea)]+ was found to be highly dependent on solvation. The calculated standard for reaction 2 (∆Go R = -0.65±0.53) and reaction 3 (∆Go R = -2.01±1.99) were found to fall within two standard deviations of experimental values, whereas reaction 1 (∆Go R = 5.20±0.95) assumed a value beyond two standard deviations. The sign of the standard reaction Gibbs energies in all three reactions were however in correspondence with experimental values.
AFRIKAANS OPSOMMING: Die self assosiasie van Fluoranthene (reaksie 1), hetero-assosiasie van [PtII(1,10-Phenan throline)(N -pyrrolidyl-N-(2,2-dimethyl-propanoyl)thiourea)]+ en Fluoranthene (reaksie 2) as well as die self assosiasie van [PtII(1,10-Phenanthroline)(N -pyrrolidyl-N-(2,2-dimethyl propanoyl) thiourea)]+ (reaction 3) is ondersoek via ”Density Functional Theory”. As gevolg van die nie-kovalente karakter van all drie reaksies is twee alternatiewe benaderings implementeer ter sake die identifikasie van konformasionele voorkeur, voor strukturele optimisering. Eerstens, was die inter-molekulˆere potensi¨ele energie opper vlaktes genereer word vir reaksies 1 and 2. Vaniut die oppervlaktes was ses Fluoranthene dimere en drie [PtII(1,10-Phenanthroline)(N -pyrrolidyl-N-(2,2-dimethyl-propanoyl)thiourea)]+ · · · Fluoranthene addukte identifiseer. As gevolg van nie-planˆere alifatiese moieties verbind tot die thiourea ligand kon geen inter-molekulˆere potensi¨ele energie oppervlaktes genereer word vir reaksie 3 nie. Eerder is ’n nuwe ”Inter Fragment Nearest Neighbour” tegniek on twikkel. Die IFNN tegniek was geimplimenteer in al drie reaksies met goeie aanvangs/pre optimale strukturele orientasies. Dispersie was gevind om ’n dominante stabiliserings bydrae te lewer to die net in teraksie energie in al drie reaksies. Die elektrostatiese interaksie energie bydrae was sta biliserend in reaksies 1 en 2, en destabiliserend in reaksie 3. Die self-assosiase reaksie van [PtII(1,10-Phenanthroline)(N -pyrrolidyl-N-(2,2-dimethyl-propanoyl)thiourea)]+ was gevind om hoogs afhanklik te wees van solvasie. Die berekende standaard reaksie Gibbs energie van reaksie 2 (∆Go R = -0.65±0.53) en reaksie 3 (∆Go R = -2.01±1.99) was gevind om binne twee standaardafwykings van eksperimentele waardes te lˆe, terwyl reaksie 1 (∆Go R = 5.20±0.95) buite die twee stan daardafwykingsgrens geval het. Die berekende teken van standaard reaksie Gibbs en ergi¨e was egter in ooreenstemming met eksperimentele waardes.
Description
Thesis (MSc) -- Stellenbosch University, 2019.
Keywords
Density functionals, Fluoranthene -- Reactivity, Geometric quantization, Quantum theory, UCTD
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