Two quasi-stable lead(ii) hydrides at ambient temperature

Area of Science:

• Organometallic Chemistry
• Main group chemistry
• Lead chemistry

Background:

• Lead bromide precursors are key starting materials in organolead synthesis.
• Diisobutylaluminium hydride (DIBAL-H) is a common reducing agent in organic synthesis.

Purpose of the Study:

• To synthesize and characterize novel lead hydride complexes.
• To investigate the thermal stability and decomposition pathways of these lead hydrides.

Main Methods:

• Reaction of terphenyl lead bromide precursors with DIBAL-H in diethyl ether at low temperatures (-78 °C).
• Isolation and characterization of the resulting lead hydride complexes.
• Thermal decomposition studies in solution and solid states.
• Kinetic analysis of decomposition reactions (zero-order kinetics determined for one complex).

Main Results:

• Successful synthesis of two lead hydride complexes, {Pb(μ-H)ArPri4}2 (1) and {Pb(μ-H)ArMe6}2 (2), in good yields (60-80%).
• Isolated solids exhibit stability up to 5 °C for several weeks.
• Complex 1 decomposes to a diplumbyne (ArPri4PbPbArPri4).
• Complex 2 decomposes to a plumbylene (Pb(ArMe6)2).
• Decomposition of complex 1 follows zero-order kinetics with a rate constant of approximately 2.0 × 10⁻⁵ M min⁻¹ at 298 K.

Conclusions:

• Novel organolead hydrides can be synthesized efficiently from lead bromide precursors.
• These lead hydrides are thermally labile, undergoing distinct decomposition pathways to form carbon-metal multiple bond compounds.
• The decomposition kinetics of these compounds provide insights into their reactivity and stability.