Silver aggregation caused by Stanna-closo-dodecaborate coordination: syntheses, solid-state structures and...

Area of Science:

• Inorganic Chemistry
• Materials Science
• Coordination Chemistry

Background:

• The stanna-closo-dodecaborate anion ([SnB11H11]2-) is a versatile nucleophile.
• Silver coordination compounds offer diverse structural possibilities.

Purpose of the Study:

• To investigate the reaction of the stanna-closo-dodecaborate anion with silver electrophiles.
• To synthesize and characterize novel silver-tin clusters.
• To explore the influence of phosphine ligands on cluster aggregation and structure.

Main Methods:

• Reaction of [SnB11H11]2- with silver electrophiles ([Ag(PR3)]+, Ag+).
• Single-crystal X-ray diffraction for structural determination.
• Density functional theory (DFT) calculations for molecular orbital analysis.

Main Results:

• Formation of silver-tin bonds and clusters with varying aggregation numbers (n=2, 3, 4) depending on phosphine ligand size.
• Isolation of an octaanionic stanna-closo-dodecaborate cluster, [Et4N]8[Ag4(SnB11H11)6], with a butterfly arrangement.
• Observation of micro2- and micro3-coordination of tin to silver atoms.
• Analysis of Ag-Ag and Ag-Sn distances within the clusters.
• DFT calculations revealed stabilization through the filling of silver s-orbital-based LUMO by stannaborate HOMO electrons.

Conclusions:

• The stanna-closo-dodecaborate anion serves as a valuable building block for constructing complex silver-tin coordination compounds.
• The size of the coordinating phosphine ligand dictates the aggregation state of the silver-tin clusters.
• The electronic structure, particularly the interaction between stannaborate and silver orbitals, is crucial for the stability of these novel compounds.