Formation of a novel trinuclear spirostannoxane tin(IV) compound.: Crystal and molecular structure of [Sn(nBu)(Cl){(OCH2CH2S)2Sn(nBu)}2] and the stannolane [(nBu)Sn(SCH2CH2O)SCH2CH2OH]

The reaction of (BuSnCl3)-Bu-n and the sodium salt of 2-mercaptoethanol (1:1) in ethanol gave the compound Sn(Bu-n)(Cl){(OCH2CH2S)(2)Sn(Bu-n)}(2) (1). [(Bu-n)Sn(SCH2CH2O)SCH2CH2OH] (2) was initially isolated from the reaction of 1 with (BuMgCl)-Bu-n as a rearrangement product but was also synthesized from (BuSn)-Bu-n(O)OH and two molar equivalents of 2-mercaptoethanol. Both compounds were characterized by means of IR, Sn-119, C-13, and H-1 NMR, FAB mass spectroscopy! and elemental analyses. The structures were determined by single-crystal X-ray diffraction. 1 crystallizes in the monoclinic Cc space group (a = 18.492(3) Angstrom, b = 17.329(2) Angstrom, c = 10.787(1) Angstrom, beta = 111.88(1)degrees Z = 4), while 2 crystallizes in the orthorhombic Pbca space group (a = 14.458(2) Angstrom, b = 10.393(1) Angstrom, c = 16.479(2) Angstrom, Z = 8). 1 is a trimetallic Tin(IV) compound in which the central atom is in 6-fold coordination, while the two remaining tin atoms show 5-fold coordination. Both pentacoordinated tin atoms are bonded to a butyl group and to the oxygen and the sulfur atoms from two [OCH2CH2S](2-) ligands forming two stannolanes, which are fused with the hexacoordinated tin atom forming a distannoxane system. This arrangement is quite different from previous ladder or staircase structures. NMR data point to maintenance of this structure in solution. 2 consists of [(Bu-n)Sn(SCH2CH2O)(SCH2CH2OH)] units, which are associated via intermolecular Sn-O interactions building up a dimer. The tin atom forms two "stannolone" units by interaction with [OCH2CH2S](2-) and [HOCH2CH2S](-) ligands.