Synthesis Of NNN-type Ligand And Its Tungsten Carbene Complex

There are a wide variety of metal carbene complexes and they are widely used in different fields.The earliest metal carbene complexes are divided into Fischer carbene and Schrock carbene complexes.With the continuous development of research,the ligand used in carbene complexes evolves from monodentate ligand,bidentate ligand and futher to tridentate ligand.The metal carbene complexes with planar tridentate pincer ligands are called pincer-type carbene complexes.Owing to its variety of pincer ligand,the pincer-type carbene complexes exhibit advantages in stability and tunability.Therefore,it is extremely important to expand the scope of pincer-type carbene complexes,and it is also very challenging and valuable for research.This thesis gave a general overview of the types and applications of carbene complexes.The review part briefly summarized the two traditional metal carbene complexes,then briefly described the characteristics and recent research progress of pincer-type ligands metal pincer-type carbene complexes.The syntheses and applications of IVB,VⅢand VIB pincer-type metal carbene complexes were elaborated.The experimental part of the thesis contained the following content:1.The amino-NNN type tridentate pincer ligand with benzene ring as the linker was designed and synthesized.In order to investigate the influence of greater steric hindrance on the coordination reaction,trityl was selected as the substituent on the N atoms on both sides;on the other hand,trityl,methyl and tert-butyl group were selected as the para-substituent R of the central N atom;in order to preliminarily study the influence of different substituents on ligand coordination activity and solubility.2.In this paper,the coordination reactions of three amino-NNN-type tridentate pincer ligands with transition metal（Mo,W）precursors were studied.The significantπ-πinteractions of ligand L1（R=trityl）leads to poor solubility,and poor capability of coordination;ligand L2（R=Me）and ligand L3（R=^tBu）have better solubility,and both can coordinate with the metal precursor（^tBu O）₃W≡CPh smoothly.The complex formed by the ligand L2 and the metal precursor（^tBu O）₃W≡CPh was successfully isolated and purified in about 31%yield,and its structure was confirmed by X-ray diffraction.