STRUCTURAL CHEMISTRY OF ORGANOTIN CARBOXYLATES .4. SYNTHESIS AND SPECTROSCOPIC PROPERTIES OF DIORGANOTIN(IV) COMPLEXES WITH ORTHO-ANISIC ACID - THE CRYSTAL AND MOLECULAR-STRUCTURE OF ([NBU2SN(2-MEOC6H4COO)]2O)2

Reactions of diorganotin(IV) oxides with o-anisic acid in 1 1 and 1 2 stoichiometry afford complexes of the type [R2Sn(2-MeOC6H4COO)]2O2 (I) and [R2Sn(2-MeOC6H4COO)2] (II) (R = Me, Et, nPr, nBu), respectively. These complexes have been characterized by elemental analyses, IR and NMR (1H, 13C and 119Sn) spectroscopy, and I shown to adopt a dimeric ladder structure whereas II has the usual monomeric diorganotin dicarboxylate structure. The oxygen atom of the methoxy group of the ligand does not participate in bonding to the tin atom. This conclusion is supported by an X-ray diffraction study. The compound [nBu2Sn(2-MeOC6H4COO)]2O2, (Id), showed that in solid Id there are two unique, centrosymmetric dimers in the asymmetric unit. The individual molecules conform to the tetraorganostannoxane structure, with six-coordination being assigned to both the endocyclic and exocyclic tin atoms after consideration of close intermolecular tin to oxygen contacts. Crystals are triclinic with space group P1 and unit cell dimensions a 13.503(3), b 24.226(4), c 11.917(1) Å, α 102.21(1), β 108.54(2), and γ 89.92(1)°. The structure was refined by a blocked-matrix least-squares procedure to final R = 0.052 for 5505 reflections with I ≥ 2.5σ(I). © 1990.