Preference of di-n-butyltin compounds to build O Sn bonds in fused rings with five-six members

The reaction of salicylaldehyde (1), o-aminophenols (2a–2f), and di-n-butyltin oxide (3) to give six di-n-butyltin compounds (4a–4f) was achieved in good yields. All compounds were characterized by H, C, N, Sn NMR, mass spectrometry, IR, elemental analysis and in the case of compounds 4a, 4b, 4d and 4e by X-ray diffraction analysis. Compound 4a crystallized with trigonal bipiramidal (TPB) geometry surrounding the tin atom while 4b and 4e crystallized as dimeric molecules joined by two O Sn bonds with distorted octahedron (DOC) geometry. The X-ray structure of 4d presents one cocrystallized monomeric TBP with one dimeric DOC molecule. Correlations of rHammett vs. spectroscopic values were found for 4a–4b and 4d–4f, indicating the substituents in the aromatic ring derived from o-aminophenol serve as modulators of the O Sn supramolecular interaction. The O Sn bond formation is selective for the five-membered ring oxygen atom. 2004 Elsevier B.V. All rights reserved.