Hexameric Organotincarboxylates with Cyclic and Drum Structures

The interaction of 3,5-diisopropylsalicylic acid (DIPSA) with [ n Bu2Sn(O)] in benzene proceeds with elimination of water to produce stannoxane [ n Bu2Sn(3,5- i Pr2C6H2(O)(COO))]6 (1), while an analogous reaction of DIPSA with [ n BuSn(O)(OH)] leads to the isolation of [ n BuSn(O)(3,5- i Pr2C6H2(OH)(COO))]6 (2). The new products have been characterized by elemental analysis and EI-MS, IR, and NMR (1H, 13C, and 119Sn) spectroscopy. The molecular structure of 1 determined by single-crystal X-ray diffraction studies reveals a rare cyclic hexameric structure. The tin atoms are pentacoordinated with distorted trigonal-bipyramidal geometry. Complex 2 is also a hexameric cluster, but existing in a more common drum-like structure where the tin centers are hexacoordinated.