 The result is a net of interconnected four-membered Sn2O2 and eight-membered Sn4O4 rings.The presence of pentacoordinate Sn centers is deduced from 119Sn NMR spectroscopy and 119Sn Mössbauer spectroscopy.In organic synthesis, among its many applications, it is particularly useful in directing regioselective O-alkylation, acylation, and sulfonation reactions for diols and polyol.