Synthesis And Structural Characterization Of Substituted Aromatic Acid Titanocene And Zirconocene Complexes In Aqueous Media

Supramolecular chemistry is an important extension of the chemical field. It's a ligament of life science and material science etc. The supramolecular recognition and self-assembly are the two contents of the supramolcecular chemistry and the supramocleular interactions, such as hydrogen bonding, Ï€-Ï€ stacking, C-H…π interactions and electrostatic interaction, are the core of them. The study of supramocleular forces between two adjacent molecules contributed significantly to the structure and characters of a compound. Furthermore, there is much interest in the properties of titanocene and zirconocene derivatives due to their ability to catalyse the polymerization of olefinic monomers, hydrogenation and isomerization, antitumour activity and antioxidative agents and their potential superacid catalysis. Benzoic acid derivatives occupy an important position in animate being, so the synthesis of substituted benzoic titanocene and zirconocene derivatives might provide necessary data and basic theories about their physiologically activity and catalysis. In order to study the crystal structures and the supramolecular forces of substituted benzoic titanocene and zirconocene, sixteen titanocene and zirconocene complexes were synthesized, of which nine are new complexes, and fourteen single crystals were grown and studied. The main contents of this dissertation are as follows:1. Based on the reaction between bis(η⁵-cyclopentadienyl) dichlorotitanium (Cp₂TiCl₂) and a series of substituted salicylic acids in the presence of p-cyclodextrin polymer (P-CDP), four titanocene complexes, thiosalicylate titanocene (1), 3,5-dichlorosalicylate titanocene (2), 3,5-dinitrosalicylate titanocene (3) and 3,5-dibromsalicylate titanocene (4) were synthesized in high yields and characterized by elemental analysis, IR and ¹H NMR spectra. Single-crystal X-ray analysis shows the mononuclear forms of Ti^IV and geometries at titanium atoms are distorted tetrahedrons, the coordinate numbers are four. Each of the complexes exhibits a three-dimensional framework constructed through weak interactions, especially H-bonding and C-H…π interactions. Interestingly, the three-dimensional supramolecular network of complex 1 consists of one-dimensional roughly square channels, which accommodate guest benzene molecules. It is also important to note that there are significant face-to-face Ï€-Ï€ stacking interactions between the two layers of complexes 2, 3 and 4, which furtherstabilize their structures. But no %-n stacking interaction is observed in the channel packing of complex 1. Additional weak interactions, such as Cl-Cl interactions in complex 2 and 4, are also present and help form stable and crystalline materials. It is noteworthy that dramatic changes in weak interactions of three complexes as well as their specific framework structures are induced by different substituted group of salicylate ligands. In addition, base on the structure of complexes 1 and 1', the influence of solvent on the structure of titanocene complexes was studied.2. When the reaction mixture carried out under different conditions, such as time, pH value, proportion of titanocene dichloride and 5-nitrosalicylic acid in the presence of transition ligand, acetylacetone, two four-coordinated titanocene complexes, single substituted and double substituted of 5-nitrosalicylic titanocene (5 and 6) have been synthesized. Single-crystal X-ray analysis of 5 and 6 displays the mononuclear forms of TiIV and geometries at titanium atoms are distorted tetrahedrons, while the coordination environment at Tiiv in complex 5 is different from that in complex 6. Crystallographic characterization revealed that each of the complexes exhibits a three-dimensional framework constructed through weak interactions, which are H-bonding, tc-tc stacking and C-H-Ti interactions, but they differed greatly when forming the three-dimensional network structure in both complexes. The results show that the dramatic change of conditions has a great effect on the molecular structure of 5-nitrosalicylate titanocene, thereby significantly influencing the weak interactions and the specific framework structure.3. Based on the reaction between bis(n5-methylcyclopentadienyl) dichlorotitanium [Cp^TiCb (Cp' = T|5-C5H4Me)] and substituted salicylic acids in the presence of (3-CDP, seven titanocene complexes, salicylate dimethyltitanocene (7), 3,5-dichlorosalicylate dimethyltitanocene (8), 5-nitrosalicylate dimethyltitanocene (9), 3-hydroxy-2-naphthoic dimethyltitanocene (10), l-hydroxy-2-naphthoic dimethyltitanocene(ll), 3,5,6-trichloro -salicylate dimethyltitanocene (12) and 3,5-dibromsalicylate dimethyltitanocene (13) were synthesized in high yields and five single crystals grown in dichloromethane-hexane, The complexes were characterized by elemental analysis, IR and !H NMR spectra. X-ray analysis of complexes 7 11 shows that each of the complexes exhibits a four-coordinated, distorted tetrahedron structure. Each substituted salicylic acid acts as a bidentate ligand and coordinates with TiIV to form a cyclic compound. Various supramolecular forces, such as C-H"O, O-H"O, C-H"-7i interactions and F-tape n-n stacking, exist in the crystal structures of the 7 11, andthey are the most important forces in stabilizing the crystal structure and forming the supramolecular compounds.4. Three "cage" "half-sandwich" zirconocene complexes, 2,4-dichlorobenzoic zirconocene (14), 2-chlorobenzoic zirconocene (15) and 3,5-dibromsalicylate zirconocene (16) have been synthesized by reaction of Cp2ZrCl2 and aromatic acid derivatives in aqueous media (aqueous method or two phases method) and grown in dichloromethane-ether-hexane. The complexes were characterized by elemental analysis, IR and !H NMR spectra and X-ray diffraction analyses. The results show that the substituted benzoic acid acts as a bidentate ligand and coordinates with Zr to form a three nuclear "cage" compound in 14 and 15. The compound 16 consists of six "CpZr" fragments held together by nine 3,5-dibromsalicylato ligands to form a nanoscopic cage. The dianionic deprotonated 3,5-dibromsalicylic acid adopts a bridging chelate \i2-(O, O', O") coordination mode, which is not common in transition-metal compounds and particularly rare in Group 4 complexes. The six metal atoms make up a twisted tripyramidal prism. It is noteworthy that hydrogen bonds, C-H--71 interactions and n-n stacking interactions are of very importance in three zirconocene complexes, where they have contributed significantly to self-assembly and molecular recognition processes.