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| Conference Presentation (After Call) | PUBDB-2018-03855 |
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2018
Abstract: Since 2003, we have been investigating the use of pentaphosphaferrocene [CpRFe(η5-P5)] (CpR = η5-C5R5, R = Me, CH2Ph, PhC4H9) as a building block in supramolecular chemistry. The phosphorus atoms of the planar P5-rings are able to coordinate to Cu+ and Ag+ (M+) cations resulting in either coordination polymers with Mx(halogen)y fragments as nodes or in self-assembled spherical hollow supramolecules of 2.1–4.6 nm in diameter [1-3]. Both coordination polymers and supramolecules can serve as matrices or molecular containers for various small molecules. For example, we succeeded in the encapsulation of metallocenes such as Cp2Co+ [2] (Fig.1a) as well as of metastable molecules such as the tetrahedral molecules white phosphorus, P4, and yellow arsenic, As4 [3] (Fig.1b).A new direction of our research is to connect giant supramolecules by organic linkers to form coordination polymers with entire supramolecules as nodes. Thus, the coordination of Ag+ cations to the P5-rings results in the in situ formation of supramolecules, while the additional coordination of Ag+ to N-donor atoms of N≡C(CH2)nC≡N (Ln, n=5-10) (Ln) flexible linker, in turn, leads to 1D, 2D and 3D coordination polymers in one-pot reactions. Depending on the experimental conditions, coordination polymers with mononuclear Ag+ nodes can also be obtained. The composition and structure of the supramolecules as well as the dimensionality of the polymer can be controlled by changing the reaction stoichiometry or by adding guest molecules as P4. Thus, in the presence of P4, two new 1D-polymers were obtained, (P4)@[(Cp*FeP5)9Ag8(L10)4](SbF6)9 (Fig.1c) and [(Cp*FeP5)2Ag2(μ,η2-P4)(SbF6)]SbF6 (Fig.1d). The former contains polynuclear cationic nodes of [Ag9(Cp*FeP5)9]9+ that encapsulates tetrahedral P4 molecules in the central cavity.Effective collaboration between chemists and crystallographers allowed developing effective crystallization methods, skilled crystal handling and proper single-crystal X-ray data collection techniques to perform structural studies at atomic resolution. As a result, fine details of structures containing hundreds of heavy atoms could be analysed, shedding light on the nature of host-guest interactions. In addition to the usual methodological problems as for instance severe crystallographic disorder, the structural studies are occasionally encumbered by the appearance of modulated or incommensurate structures.Financial support from the ERC grant ADG 339072 is gratefully acknowledged. Parts of these investigations were carried out at PETRA III synchrotron source at DESY, a member of the Helmholtz Association (HGF).Fig. 1. a) encapsulation of Cp2Co+ in the supramolecule; inclusion of E4 (E=As, P) molecule into b) coordination polymer and c) into [Ag9(Cp*FeP5)9]9+ cage. d) [(Cp*FeP5)2Ag2(μ,η2-P4)(SbF6)]SbF6.References[1] Heindl, C. et al (2017) Angew. Chem. Int. Ed. 56, 13237-13243. [2] Peresypkina, E. et al (2018) Chem.-A Eur. J. 2018, 24, 2503 – 2508.[3] Schwarzmaier, C. et al (2013) Angew. Chem. Int. Ed. 52, 10896-10899.
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