R3Sn

R3Sn denotes the triorganostannyl moiety used in organotin chemistry. It describes a tin atom bonded to three hydrocarbon groups (R) and to the remainder of a substrate, giving compounds of the form R3Sn–R′ or, in common reagents, R3Sn–X or R3Sn–H where X is a halide or hydrogen. The term is most often applied to reagents in which three alkyl groups are attached to tin, such as tributyltin hydride (Bu3SnH) and tributyltin chloride (Bu3SnCl). In cross‑coupling contexts, the general form is R3Sn–R′, where R is the transferable group and the tin center facilitates substitution at a catalytic metal center (for example, in Stille couplings).

Key applications include radical and stoichiometric transformations. Tributyltin hydride is widely used as a hydrogen donor in radical hydrostannylation, enabling addition of a tin-containing fragment across double or triple bonds under radical initiation. The resulting alkylstannane intermediates can be further manipulated, including selective functionalization or deborylation, under controlled conditions. In carbon–carbon bond formation, organotin reagents of the form R–SnBu3 participate in Stille-type cross‑coupling reactions with aryl or vinyl electrophiles under palladium catalysis, allowing construction of complex molecular architectures with a broad tolerance for functional groups.

Safety and regulation are important considerations. Organotin compounds are often toxic and environmentally persistent; handling requires appropriate containment, and waste disposal is subject to hazardous waste guidelines. Proper sourcing and compliance with relevant regulations are essential in research and industrial use.

See also organotin chemistry, tributyltin, Stille coupling, hydrostannylation.