Structural studies of diorganotin(IV) sulphonates The crystal structures of [(n-C4H9)2Sn{μ-OSO2C6H2(CH3)3}2]n and its partially hydrolyzed product [(n-C4H9)2Sn{(μ-OH)(μ-OSO2C6H2(CH3)3)}]n

The X-ray crystal structures of [(n-C4H9)2Sn{μ-OSO2C6H2(CH3)3}2]n (1) and [(n-C4H9)2Sn{(μ-OH)(μ-OSO2C6H2(CH3)3)}]n (2) were determined to delineate the coordination behaviour of the sulphonate group with tin(IV) and to evaluate the metal sulphonate bonding interactions. The synthesis of 1 has been achieved by azeotropic dehydration of di-n-butyltin(IV) oxide and mesitylenesulphonic acid. 1 is polymeric containing six-coordinate tin and crystallizes from anhydrous toluene in the orthorhombic space group P21212 with unit cell dimensions a=12.555(1), b=21.238(1), c=5.415(1) Å; Z=2; R, 0.0236 and wR, 0.0607 for 1281 observed reflections. The structure exhibits highly symmetrical bridging bidentate mesitylenesulphonate groups and is made up of an infinite array of (n-C4H9)2SnO4 moieties. Compound 1 hydrolyzes very slowly to [(n-C4H9)2Sn{(μ-OH)(μ-OSO2C6H2(CH3)3)}]n (2), when kept in CH3OH–CHCl3 mixture at room temperature for 35 days. Crystals of 2 are monoclinic with space group P21/m and unit cell dimensions a=10.040(1), b=14.500(1), c=13.978(1) Å; β=91.58(1)°; Z=4; R, 0.0226; wR, 0.0592 for 2725 observed reflections. The crystal structure is built of polymeric chains in which [{(n-C4H9)2Sn}2(OH)2] units are joined by bridging bidentate meistylenesulphonate groups. The crystal lattice is stabilized by a network of hydrogen bonds running through the sheets, in which an oxygen atom of the sulphonate group and the hydroxyl group attached to tin participate in a symmetrical fashion. In DMSO solutions, chemical shift (119Sn) and 1J (119Sn–13C) values for both 1 and 2 suggest a distorted octahedral geometry around tin in which DMSO may also be involved.