In Silico Studies of Functionalized Aromatic Heterocyclic and Zintl Ion Based Superatom/Alkali/Halogen

Abstract

Atomic clusters have emerged as a new phase of matter, whose properties are not only dependent on size and composition but also on the geometrical arrangements. One of the major goals of cluster science has been to use clusters as building blocks of materials with tailored properties. Two important sets of clusters that belong to this category are superalkalis and superhalogens. Apart from these molecules, another kind of cluster, known as Zintl cluster has a very special chemistry. Considering the potential applications of these compounds in vivid fields, in this thesis several superalkali and superhalogen molecules as well as Zintl clusters have been designed and their stability, reactivity, aromaticity etc. were investigated in the light of different electron counting rules and Density Functional Theory treatment. The thesis is segregated into eight chapters. Chapter 1 provides a short account of the current status of research in the area of cluster science and the methodologies employed in this thesis. Aromatic heterocyclic superhalogen and superalkali complexes have been designed using Huckel π-aromaticity rule in Chapter 2. Effect of the nature of the ligands in making such super halogen /alkali complexes have been discussed thoroughly in this chapter. Chapter 3 provides information on the possible application of such molecules in making electrolytes for Li-ion battery and super Lewis acid. Comparison with commonly used electrolytes and Lewis acid depicts the potency of the designed organic superhalogen molecules. A new class of superhalogen based on group 14 Zintl ion has been designed in Chapter 4. The bonding pattern, hybridizations, effects of ligands have been thoroughly discussed in this chapter. Chapter 5 tells the story of making superalkali complexes from group 15 Zintl ions. Different aliphatic ligands like, Me, CH2Me, CH(Me)2 and C(Me)3 have been used to make superalkali complexes. In Chapter 6 superatoms have been designed by using Zintl ions Ge9 4- and Ge9 2- as cores and -CHO as ligand. The electron affinities of resulting [Ge9(CHO)3] and [Ge9(CHO)] complexes are found to be comparable to those of chlorine and iodine, respectively. In addition, comparison of MO's of these complexes with those of Cl, I, and Al13 has been performed. The similarity between the MO's further confirms the superatom character of these organo-Zintl complexes. Attempt has been made in Chapter 7 to see the possible effect of doping on deltahedral Zintl cluster Ge9 4- . A possible extension of the concept of Zintl ions has been employed in this chapter to design an all metal version of magnetic Zintl like phases, M3Au5Ni [where M =Na, K]. In Chapter 8, a detailed study revealed a complete reversal in the reactivity trends of the Boron-center in the Zintl based cluster B[Ge9Y3]3 (Y = H, CH3, BO, CN) as compared to that in B(C6X5)3 (X = F, BO, CN). Detailed charge analyses on the various atomic sites using different basis sets and levels of theory showed that the B-center in B[Ge9Y3]3 (Y = CH3, BO, CN) is nucleophilic