A heterobimetallic tetrahedron from a linear platinum(II)-bis(acetylide) metalloligand.

Matthias Hardy,Marianne Engeser,Arne Lützen

doi:10.3762/bjoc.16.220

Abstract

Employing 4-ethynylaniline as a simple organic ligand we were able to prepare the stable trans-bis(acetylide)platinum(II) complex [Pt(L1)2(PBu3)2] as a linear metalloligand. The reaction of this metalloligand with iron(II) cations and pyridine-2-carbaldehyde according to the subcomponent self-assembly approach yielded decanuclear heterobimetallic tetrahedron [Fe4Pt6(L2)12](OTf)8. Thus, combination of these two design concepts – the subcomponent self-assembly strategy and the complex-as-a-ligand approach – ensured a fast and easy synthesis of large heterobimetallic coordination cages of tetrahedral shape with a diameter of more than 3 nm as a mixture of all three possible T-, S4- and C3-symmetric diastereomers. The new complexes were characterized by NMR and UV–vis spectroscopy and ESI mass spectrometry. Using GFN2-xTB we generated energy-minimized models of the diastereomers of this cage that further corroborated the results from analytical findings.

Highlights

The understanding of the general design principles for the selfassembly of metallosupramolecular aggregates [1-5] allowed to access more and more complex and large assemblies over the past decades like sophisticated cage-in-ring structures [6,7], interlocked rings [8] and catenanes [9-12] or giant spheres [13,14].Increasing the structural complexity, usually implies growing synthetic efforts that have to be made to obtain the necessary organic ligands [15-17]
The actual ligand is generated in situ during the self-assembly process via reversible formation of covalent bonds, in most cases imine bonds
Analysis of the 1H NMR spectrum of 4 shows signals that clearly indicate the presence of various diastereomeric cages, and the self-assembly does not occur in a diastereoselective manner

Summary

Introduction

The understanding of the general design principles for the selfassembly of metallosupramolecular aggregates [1-5] allowed to access more and more complex and large assemblies over the past decades like sophisticated cage-in-ring structures [6,7], interlocked rings [8] and catenanes [9-12] or giant spheres [13,14].Increasing the structural complexity, usually implies growing synthetic efforts that have to be made to obtain the necessary organic ligands [15-17]. Ensured a fast and easy synthesis of large heterobimetallic coordination cages of tetrahedral shape with a diameter of more than 3 nm as a mixture of all three possible T-, S4- and C3-symmetric diastereomers.

Results

Conclusion