Hexameric Organotincarboxylates with Cyclic and Drum Structures

The interaction of 3,5-diisopropylsalicylic
acid (DIPSA) with [nBu2Sn(O)] in benzene proceeds with
elimination of water to produce stannoxane [nBu2Sn(3,5-iPr2C6H2(O)(COO))]6 (1), while an analogous reaction of
DIPSA with [nBuSn(O)(OH)] leads to the isolation of
[nBuSn(O)(3,5-iPr2C6H2(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.