Reversible Coordination of H₂ by a Distannyne

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Tin Chemistry

Background:

• Tin(II) hydrides are reactive species with complex coordination chemistry.
• Understanding the stability and reactivity of tin hydrides is crucial for developing new synthetic methodologies.
• The formation of tin clusters from smaller precursors is an active area of research.

Purpose of the Study:

• To investigate the equilibrium between a specific tin(II) hydride, a distannyne, and hydrogen.
• To explore the thermal decomposition pathway of the tin(II) hydride and its derivatives.
• To characterize the properties of the tin(II) hydride, including its acidity and bond dissociation energy.

Main Methods:

• ¹H NMR spectroscopy and UV-vis spectroscopy were used to determine equilibrium constants and Gibbs free energy.
• Cyclic voltammetry was employed to characterize the tin(II) hydride.
• Titration with 1,8-diazabicyclo[5.4.0]undec-7-ene was used to determine the pK_a.

Main Results:

• The tin(II) hydride [Ar^iPrSn(μ-H)]₂ exists in equilibrium with Ar^iPrSnSnAr^iPr and H₂, with the hydride form strongly favored.
• The distannyne intermediate decomposes at higher temperatures to form a known pentagonal-bipyramidal Sn₇ cluster.
• The tin(II) hydride exhibits a pK_a of 18.8(2) and a bond dissociation free energy of 51.1 kcal/mol.

Conclusions:

• The tin(II) hydride is thermodynamically stable relative to its distannyne and H₂.
• The tin(II) hydride serves as a precursor to tin clusters via a distannyne intermediate.
• The characterized properties provide valuable data for understanding tin hydride reactivity and stability.