Triorganotin compounds five-coordination

X-ray diffraction studies on hydrated triorganotin compounds H2O — SnRsX have provided several examples of water engaged in inner-sphere coordination to tin in five-coordinate molecules. For inner-sphere coordination, the complexes tend to pack in arrangements in which the number of hydrogen bonding interactions involving the coordinated water molecule is maximized. For example, o-phenanthroline monohydrate, which chelates to a plethora of transition metals, forms with triphenyltin chloride an outer-sphere coordination complex in which the coordinated water molecule [O — Sn = 2.42 A]... 

In the condensed phase Me3SiF molecules show no intermolecular interactions, while the same germanium derivatives are associated as a dimer due to intermolecular F Ge coordination. According to the tendency for tetrahedral main-group 14 elements to expand the coordination sphere, organotin fluorides show a strong tendency to associate in the solid state and even in triorganotin fluorides the tin atom is five-coordinate A common feature of this class of compounds in the solid state is coordination expansion of the tin atom due to hypervalent interaction, which in turn often results in formation of polymeric materials. 

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