Synthesis And Structural Characterization Of Azo-substituted Salicylate Titanocene Complexes In Two-phase Media

Coordination chemistry is developed on the basis of inorganic chemistry, which has permeated into chemistry, industry and other branches, and with the development of supramolecular chemistry, coordination chemistry has received new vigor and growing points. Now supramolecular chemistry has become a cross field of chemistry, physics, material science, life science etc. The supramolecular recognition and self-assembly are the two contents of the supramolcecular chemistry and the supramocleular interactions. In the supramolecular system, the non-covalent function, such as hydrogen bonding,Ï€-Ï€stacking, C-H…πinteractions and electrostatic interaction, gathers the molecules together. The study of supramocleular forces between two adjacent molecules contributed significantly to the structure and characters of a complex. There is much interest in the properties of titanocene complexes due to their ability to catalyse the polymerization of olefinic monomers, hydrogenation and isomerization and to act as antitumour activity and antioxidative agents. Azo-salicylic acid derivatives, as important dyes, get unprecedented development in the field of information materials and also can be use as activity ligands. In order to study the crystal structure and the supramolecular forces of substituted azo-salicylic titanocene with-N=N-group, eight titanocene complexes were synthesized, all of which are new complexes, and four single crystals were grown and studied. The main contents of this dissertation are as follows:1. Four azo-salicylic acids: [5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids, have been prepared by literature method and identified by IR and ¹H NMR spectra.2 Based on the reaction between bis(η⁵-cyclopentadienyl) dichlorotitanium (Cp₂TiCl₂) and the azo-salicylic acids in two phase system, four titanocene complexes, [Cp₂Ti{O₂CC₆H₃(O-2)(N=NC₆H₅-5)}] (1), [Cp₂Ti{O₂CC₆H₄(O-2)(N=NC₆H₄(CH₃-4)-5)}] (2), [Cp₂Ti {O₂CC₆H₄(O-2)(N=NC₆H₄(Br-4)-5)} ] (3) and [Cp₂Ti{O₂CC₆H₄(O-2) (N=NC₆H₄(OCH₃-4)-5)}] (4) were synthesized and characterized by elemental analysis, IR and ¹H NMR spectra. Single-crystal X-ray analysis shows that Ti^â…£of complex 3 is surrounded by two methylcyclopentadienyl moieties and one oxygen atom of hydroxyl and one carboxyl oxygen atom of [5-(4-Br)C₆H₄N=N(2-OH)C₆H₄COOH]. The [5-(4-Br)C₆H₄N=N(2-OH)C₆H₄COOH] acts as a bidentate ligand and coordinates with Ti^â…£to form a stable hexacyclic compound. The analysis of the crystal packing of 3 shows a three-dimensional framework constructed through complicated intermolecular hydrogen bonds and C-H-…πinteractions. Unexpectedly, there are noÏ€-Ï€stacking interactions are observed between naphthalene rings and cyclopentadienyl rings in the packing diagram.3. Based on the reaction between bis(η⁵-methylcyclopentadienyl) dichlorotitanium [Cp'₂TiCl₂ (Cp'=η⁵-C₅H₄Me)] and the azo-salicylic acids in two phase system, with acetylacetone as the transition ligand, four titanocene complexes, [Cp'₂Ti{O₂CC₆H₃(O-2)(N=NC₆H₅-5)}] (5), [Cp'₂Ti{O₂CC₆H₄(O-2)(N=NC₆H₄(CH₃-4)-5)}] (6), [Cp'₂Ti{O₂CC₆H₄(O-2)(N=NC₆H₄(Br-4)-5)}] (7) and [Cp'₂Ti{O₂CC₆H₄(O-2)(N=NC₆H₄(OCH₃-4)-5)}] (8) were synthesized and characterized by elemental analysis, IR and ¹H NMR spectra. X-ray analysis of complexes 5, 7 and 8 shows each of the complexes exhibits a four-coordinated, distorted tetrahedron structure, each asymmetric unit contains one titanium atom, two methylcyclopentadienyl rings and one azo-salicylic acid ligand, which similar to that of complex 3. Various supramolecular forces, such as C--H…O, C-H…πinteractions and F-tapeÏ€-Ï€stacking and Br…Br interaction exist in the crystal structures of 5, 7 and 8, which are the most important forces in stabilizing their crystal structures, forming the supramolecular complexes as well as constructing the three-dimensional supramolecular framework.