Chalcogeno[bis(phosphaalkenyl)] germanium and tin compounds.

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Coordination Chemistry

Background:

• Carbene ligands, particularly N-heterocyclic carbenes (NHCs), are crucial for stabilizing reactive main group element species.
• Low-valent phosphorus and silicon compounds are known, but analogous tin and germanium systems are less explored.
• The synthesis and reactivity of low-coordinate main group compounds offer insights into bonding and reaction mechanisms.

Purpose of the Study:

• To synthesize and characterize the first diphosphaalkenylstannylene stabilized by an NHC ligand.
• To investigate the reactivity of this stannylene and its germanium analogue towards chalcogens (sulfur and selenium).
• To explore the formation of novel cyclic tin and germanium-chalcogenide species.

Main Methods:

• Synthesis of NHC-stabilized diphosphaalkenylstannylene and its germanium analogue.
• Characterization using single crystal X-ray diffraction analysis.
• Reactions with elemental sulfur and selenium to form new compounds.

Main Results:

• Isolation and full characterization of the first NHC-stabilized diphosphaalkenylstannylene (NHC-Sn[C(Cl)═PMes*](2)).
• Reaction with sulfur yielded a cyclic Sn(2)S(2) derivative, likely via a stannathione intermediate.
• The germanium analogue formed monomeric germathione and a more stable, structurally characterized germaselenone.
• An unusual thermal cyclization of the germaselenone with excess selenium produced a Ge(2)Se(3) ring derivative.

Conclusions:

• NHC ligands effectively stabilize reactive low-valent tin and germanium species.
• The reactivity towards chalcogens differs between tin and germanium, leading to distinct product types.
• Novel cyclic tin and germanium-chalcogenide structures were accessed, expanding the chemistry of these elements.