Diphenylphosphino Pyridine Transition Metal Complexes Of Structure And Properties Of Theoretical Research

Along with the rapid development of computational methods and computer technology, computational chemistry has become more and more important in modern chemistry. Due to its moderate computational consume and high precision, density functional theory (DFT) has become one of the most important methods in computational chemistry. Heterometallic complexes with Ph₂PPy have been subjected to extensive investigation in recent decades owing to their unique structures, reactivities and spectroscopic properties. Taking advantage of rapid progress in computational chemistry, now it is possible to study the geometry, electronic structure and many other properties of transition metal complexes from frist-principles calculations, and get more and accurate information. This dissertation is to study the bonding nature, the ³¹PNMR and UV absorption spectra properties of transition metal complexes from DFT method. Having a clear picture of the nature of transition-metal-metal and metal-ligand bonding is important in understanding structures, properties and reactivity of transition metal complexes. Knowledge of mechanistic aspect is very useful in designing better and effective catalysts and luminescence materials.In Chapter 1, The basic concept and progress of DFT were introduced. Thomas-Fermi model was the first theory using density of electrons as the main variable. Theorem of Hohenberg-Kohn was the fundament of DFT and was developed to Kohn-Sham equation, which could be used to perform real calculations. Now, new corrections and extensions, together with developed exchange-correlation functionals, have made DFT more accurate and suitable for more systems. In addition, we introduced the natural bond orbital (NBO) methods, which is increasingly important in bonding analysis and can be used for DFT methods.In Chapter 2, Complexes with Ph₂PPy were introduced briefly. The synthesis and reactivity binuclear complexes with Ph₂PPy have assumed considerable interest because of the novel structural and reactive features of these complexes, and their potential as catalysts. At first, we introduced the different kinds of complexes with Ph₂PPy. Then,studies on transition complexes were reviewed. At last, we simply described the purpose of this thesis studied on complexes with Ph2PPy.In Chapter 3, the structural, bonding characteristics and stability of hereodinuclear transition metal complexes [Ru(CO3Xn-Ph2PPy)2MCI2](M=Zn, Cd, Hg: 2, 3, 7) and [Ru(CO3Xu.-Ph2PPy)2MCI]+(M=Zn, Cd, Hg: 5, 6, 4) were studied using the DFT method with the generalized gradient approximation (GGA), and with the hybrid functional. At first, we explored computational model and methods suited for these transition metal systems. The results showed that the PBEO model with SDD basis set on the metal atoms systemically agreed well with the experiment data, resulting in the success of the methods for predicting the structures of these transition metal systems. Then, theoretical calculations were undertaken to optimized molecular structures and elucidate the nature of metal-ligand, metal-metal interactions and stability of these heterobinuclear d6-d10 systems. From comparing binding energy AE of neutral systems [Ru(CO)3(PPh2Py)2MCl2] (M=Zn, Cd, Hg: 2, 3, 7) and cation systems [Ru(CO)3(PPh2Py)2(MCl)]+(M= Zn, Cd, Hg: 5, 6, 4), it showed that system [Ru(CO)3(PPh2Py)2HgCl2] was not easy to get, while system [Ru(CO)3(PPh2Py)2(ZnCI)]+ could be in existence. Meanwhile experimental complexes 2, 3 and 4 were all comparatively stable and the stability order was: 2³?4, which was in consistence with the experimental result. At last, bonding analysis was performed for the experimental complexes 2-4 to investigate the unusual metal-metal donor-acceptor bonding interactions with the aid of DFT calculations at the level of PBEO and NBO analysis. The combination between trans-[Ru(2-Ph2PPy)2(CO)3] and ZnCl2(CdCl2) was explained with the metal—metal and N—metal donor-acceptor interactions, while a o-bond between Ru and Hg resulting from the overlap of an sd3 '3 hybrid on Ru with an sd°...