Design, Synthesis And Application Study Of Iridium Complexes Basing On Nitrogen, Phosphine Skeleton Ligands

Iridium complexes have attracted more and more chemists’ s attention due to its advantages both in the field of organic optoelectronic materials and chemical catalysis. In general, the iridium complexes are more stable than the rhodium and cobalt complexes, research using Ir catalyst has made tremendous progress since the report of the Crabtree hydrogenation catalyst, and C-N bond and C-C bond forming recations with iridium catalysis have increasingly attracted chemists pro-gaze over the past decade. The affinity between the transition metal iridium and trivalent phosphorus compound is strong, and they can form stable complex. Therefore, our work was foucsed on the design, synthesis and application study of iridium complexes basing on nitrogen, phosphine skeleton ligands.(1) First, a series of nitrogen phosphine ligand iridium(III) complexes were designed and synthesis by our laboratory existing [{(bt)2Ir(?-Cl)}2] and [{(bo)2Ir(?-Cl)}2] reacted with commonly known organic phosphine ligands, and their structures were determined by NMR and X-Ray characterization. Our complexes have stability structure, can be stable in the air, and have good stability thermal properties, their phosphorescence excitation light belonging to the the green region of the visible light. When these iridium complexes with phosphines as ancillary ligands were tested in this reaction of N-alkylation of amine with amine, the yields of the product were obtained with approximately moderate yield. It was observed that the catalytic activity of iridium complexes was enhanced by the phosphine ligand. As we all know, ionic complexes are easily coordinated with substrates and may have better catalytic reactivity. When these ionic complexes in situ formed through the addition of Ag X were used to this N-alkylation reaction, and the results showed that the yield was significantly increased. The experiments showed that different N-alkylated anilines were obtained with moderate to good yields through the use of the catalyst [Ir]/Ag X. It shown the catalyst has excellent catalytic activity, simple reaction conditions and the experiment is easy to operate.(2) Second, the reactive intermediates—iridium-CNP complexes with coordinating anion, obtained by the reaction of phosphine-assisted iridium complexes with anionic agents Ag X—were isolated and characterized. These complexes have good stability thermal properties and are not sensitive to air, their phosphorescence properites have almost no changes by coordinating anion. These iridium complexes exhibit excellent catalytic activity and high selectivity of the C-N bond formation reation by alkylation of aromatic amines with alcohols using the borrowing hydrogen strategy when compared with the traditional method. The results showed different N-alkylated anilines were obtained with good to excellent yields with optimized condition.(3) Last, These C-C bond formation reations of cross-coupling of secondary alcohols and primary alcohols, direct α-alkylation of ketones with primary alcohols, and dehydrogenation of secondary alcohols were catalyzed by iridium-CNP complex with coordinating anion. The reactions are compatible with substrates bearing diverse functional groups and proceed efficiently under mild conditions, and aromatic alcohols, Straight-chain and branched-chain aliphatic alcohols, furyl-, thienyl-, pyridyl-heterocyclic alcohols could react under the optimal reaction conditions with gratifying yield. The present methodology provides an easy alternative to synthesis of functionalized ketones derivatives.