Ring-opening polymerisation of silver-diphosphine [M2L3] coordination cages to give [M2L3]infinity coordination...

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Investigation of rigid, bridging diphosphines bis(diphenylphosphino)acetylene (dppa) and trans-1,2-bis(diphenylphosphino)ethylene (dppet) with silver(I) salts.
• Exploration of coordination cage and polymer formation in solution and solid states.
• Contrast with flexible diphosphines, which form dynamic mixtures rather than discrete macrocycles.

Purpose of the Study:

• To synthesize and characterize novel [M2L3] coordination cages and linear [M2L3]infinity polymers using rigid diphosphines and silver(I) salts.
• To investigate the influence of anion nucleophilicity on cage structure and properties.
• To explore the potential for ring-opening polymerization of these coordination cages.

Main Methods:

• Synthesis of silver(I) complexes with dppa and dppet.
• Characterization using X-ray crystallography and 31P NMR spectroscopy.
• Analysis of anion nucleophilicity effects on cage geometry and stability.

Main Results:

• Selective formation of [M2L3] triply bridged cage complexes [Ag2(dppa)3(X)2] with various silver(I) salts (X = SbF6, BF4, O3SCF3, NO3).
• Cages exhibit small internal cavities, helical conformations, and intramolecular aromatic interactions; anion nucleophilicity influences cage shape and Ag-Ag distances.
• Conversion of a cage complex (1c) to an isostoichiometric coordination polymer (1c') via ring-opening polymerization upon prolonged storage.

Conclusions:

• Rigid diphosphines enable the selective synthesis of novel silver(I) coordination cages.
• A new example of ring-opening polymerization is demonstrated, converting cages to infinite coordination polymers.
• The steric bulk of the diphosphine influences cage stability and the propensity for polymerization.