<P> Organotin compounds or stannanes are chemical compounds based on tin with hydrocarbon substituents . Organotin chemistry is part of the wider field of organometallic chemistry . The first organotin compound was diethyltin diiodide ((C H) SnI), discovered by Edward Frankland in 1849 . The area grew rapidly in the 1900s, especially after the discovery of the Grignard reagents, which are useful for producing Sn - C bonds . The area remains rich with many applications in industry and continuing activity in the research laboratory . </P> <P> Organotin compounds are generally classified according to their oxidation states . Tin (IV) compounds are much more common and more useful . </P> <P> The tetraorgano derivatives are invariably tetrahedral . Compounds of the type SnRR'RR' have been resolved into individual enantiomers . </P> <P> Organotin chlorides have the formula R SnCl for values of n up to 3 . Bromides, iodides, and fluorides are also known but less important . These compounds are known for many R groups . They are always tetrahedral . The tri - and dihalides form adducts with good Lewis bases such as pyridine . The fluorides tend to associate such that dimethyltin difluoride forms sheet - like polymers . Di - and especially triorganotin halides, e.g. tributyltin chloride, exhibit toxicities approaching that of hydrogen cyanide . </P>

The nature of c-sn bond in alkyl tin is