An Icosidodecahedral Supramolecule Based on Pentaphosphaferrocene: From a Disordered Average Structure to Individual Isomers

Abstract

Pentaphosphaferrocenes [Cp^R Fe(η⁵ -P₅ )] (1) and Cu^I halides are excellent building blocks for the formation of discrete supramolecules. Herein, we demonstrate the potential of Cu(CF₃ SO₃ ) for the construction of the novel 2D polymer [{Cp*Fe(μ₄ ,η^5:1:1:1 -P₅ )}{Cu(CF₃ SO₃ )}]_n (2) and the unprecedented nanosphere (CH₂ Cl₂ )_1.4 @[{Cp^Bn Fe(η⁵ -P₅ )}₁₂ {Cu(CF₃ SO₃ )}_19.6 ] (3). The supramolecule 3 has a unique scaffold beyond the fullerene topology, with 20 copper atoms statistically distributed over the 30 vertices of an icosidodecahedron. Combinatorics was used to interpret the average disordered structure of the supramolecules. In this case, only two pairs of enantiomers with D₅ and D₂ symmetry are possible for bidentate bridging coordination of the triflate ligands. DFT calculations showed that differences in the energies of the isomers are negligible. The benzyl ligands enhance the solubility of 3, enabling NMR-spectroscopic and mass-spectrometric investigations.

Keywords: density functional calculations; pentaphosphaferrocene; self-assembly; supramolecular chemistry; triflate.

Figure 1

Fivefold‐symmetric linking units.

Figure 2

Selected coordination products based on 1 a as a building block: a) 1D polymer; supramolecules with b) fullerene, c) fullerene‐like, and d) non‐fullerene topology.

Scheme 1

Reaction of 1 a and 1 b with Cu(CF₃SO₃).

Figure 3

Molecular structure of 3 in the crystal. H atoms, solvent molecules, and minor parts of disorder are omitted for clarity. a) Dodecahedron of copper halide derived from 80‐vertex balls. b) Icosidodecahedron of 3. Connectivity in the c) idealized and d) partially vacant scaffold of 3. e) The 14‐membered cycle formed as a result of the vacancies. f) The whole supramolecule 3 from X‐ray data. Only one position of a CH₂Cl₂ molecule is shown in the space‐filling model. g) D₅ isomer of 3 and h) the corresponding arrangement of Cu atoms. i) D₂ isomer of 3 and j) arrangement of the Cu atoms.

Figure 4

Section of the 2D polymeric structure of 2 based on 1 a: a) top view and b) side view of a layer.