Organometallic Half-Sandwich Self-Assemblies:Design, Synthesis And Properties

Supramolecular chemistry with organometallic half-sandwich complexes based on Ir, Rh, Ru fragments has received considerable attention over recent years. In this dissertation, some results in the rational design and synthesis of discrete organometallic half-sandwich complexes and their potential applications are presented. The advantage of the formation of these architectures via step-wise formations is, by employing functional ligands or metal centers in the assembly process, functionalities can readily be introduced onto the metallasupramolecular structures.(1) Based on the rule of addition reaction at the metal center of [Cp*M[E2C2(B10H10)](M=Ir, Rh; E=S, Se), both of cluster-based carboranyl complexes and flexible bipyridyl ligands, have been proved to be versatile precursors to accomplish diverse architectures.The probability of p-carborane derivatives as linker has also been explored. As a result, a series of microporous lanthanide coordination polymers containing p-dicarboxylate carborane ligand have been synthesized from the reactions of p-carboxylic acid with rare earth metals. Based on the well-known effect of lanthanide contraction, three distinct structure types were isolated. The structures of type Ⅰ polymers consist of four-connected2D lamellar networks, but type Ⅱ and type Ⅲ polymers are composed of six-connected3D structures. Gas sorption property of such complexes was studied, which showed selective CO2capture over CH4and N2. On the other hand, a newly tetranuclear half-sandwich iridium macrocycle was successfully obtained via cleaving B-H bonds of carborane-containing p-carboxylic acid under mild conditions.(2) The binuclear complexes with two parallel coordination sites, such as1,5-dihydroxyanthracene-9,10-dione bridging iridium, rhodium complexes can be served as precursors, which can be interlinked by pyridyl-based ligands.Many tetra-and hexanuclear organometallic self-assemblies bearing1,5-dihydroxyanthracene-9,10-dione ligands were synthesized. The tetranuclear species can be obtained if bridging ligands such pyrazine,4,4’-bipyridine are used. The hexanuclear species can also be synthesized if tpt ligand is used. Crystal structure of some tetranuclear complexes has been obtained and host-guest behavior of them has been discussed. The similarity and difference between self-assemblies bearing1,5-dihydroxyanthracene-9,10-dione and1,4-dihydroxyanthracene-9,10-dione have been discussed and compared with results of self-assemblies of6,11-dihydroxy-5,12-naphthacenedione.(3) Driven by C-H activation-directed self-assembly, a series of organometallic cages was obtained from the reaction of [Cp*IrCl2]2and tpt with terephthal-bis-aromatic imine ligands in the presence of AgOTf. In the resulting supramolecular assemblies, the two central triazine units are very close, and the centroid…centroid distance between the two triazine moieties is only3.3A. These discrete cages can form complexes with a wide variety of π-donor substrates, including Pt(acac)2, pyrene, and coronene. The transannular separation between the centers of the triazine rings in the host-guest complex is now enlarged to about6.66A. The preparation of host-guest systems in a one-pot procedure was accomplished. The1:1complexation between the guest and host was confirmed by1H NMR, elemental analyses and single-crystal X-ray diffraction analyses.(4) Self-assembly of half-sandwich iridium fragment and ditopic ligand2,4-diacetyl-5-hydroxy-5-methyl-3-(3-pyridinyl)-cyclohexanone (HL) ligand has been researched. Several half-sandwich iridium-based metallamacrocycles have been synthesized. They are assembled by linking the deprotonated2,4-diacetyl-5-hydroxy-5-methyl-3-(3-pyridinyl)-cyclohexanone ligand in the presence of counteranions. Single-crystal X-ray analysis indicated that, in the solid state, the products crystallize as tetranuclear cations according to counteranions.