Donor substituted alkynes as directional bridging ligands in polynuclear complexes

• Applicant: Professor Dr. Wolfram W. Seidel
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 272575417

The background of the intended research project is highlighted by the remarkable properties of supramolecular coordination compounds, in which specific alkyne ligands ensure strong intermetallic coupling. The linkage of different metal centers is accomplished by alkyne ligands, which bear donor groups in both alpha-positions. Side-on coordination at the triple bond turns the primarily linear alkynes into kappa2-chelate ligands. The donor centers can be a chalcogen- or a pnicogen atom. Mononuclear complexes with terminal donor groups may be regarded as functional ligands. The large bite angles due to the bend back angle in the alkyne complex moiety, the high polarizability and the prevalent redox activity of alkyne complexes with mid transition metals may lead to an unconventional coordination behavior. The specific function of these directional bridging ligands for the characteristics of their polynuclear complexes will be elucidated by a systematic variation of the donor centers.The main topic of the research project is the development of synthetic strategies for the controlled and stepwise preparation of polynuclear complexes featuring alkynes with alpha-donor centers. In turn, this goal depends on a straightforward access to alkyne complexes with free terminal donors from corresponding W(II)- or W(IV) acetylene or halogenacetylene complexes via nucleophilic substitution. Such substitution reactions on the coordinated alkyne were only sporadically and not systematically investigated. In addition to the assembling of polynuclear coordination compounds, the synthesis of otherwise difficult to make alkynes might be possible by this strategy. The electronic structures of the obtained polynuclear complexes will be comprehensively studied by spectroscopy and theory. On this basis a comparative classification and evaluation with respect to potential applications of these novel ligand systems will be accomplished.

• DFG Programme: Research Grants