Organometallic coordination polymers: Sn(IV) derivatives with the bis(triazolyl)methane ligand

Several alkyl- or aryl-tin(IV) halides of general formula SnRnX4−n (n = 0–2; R = Me, Et, nBu, tBu, Ph; X = Cl, Br), possessing Lewis acidic character, have been reacted with the polydentate N-donor ligand bis(1,2,4-triazolyl)methane (Btm), affording Btm(SnRnCl4−n) complexes. (Btm)2SnnBu2Br2 and (Btm)SnnBu2(NO3)2 are also reported. These materials were characterized by elemental analyses, IR and 1H (and, in selected cases, 119Sn) NMR spectroscopy, and, were possible, ab initio X-ray powder diffraction methods. The crystal structures determined by the latter method showed that Btm ligands, in the exobidentate mode, link Sn(IV) fragments which lie 9.5–11.2 Å apart (depending on the Btm conformation and on the local metal stereochemistry), in one-dimensional chains packed in parallel bundles. The main geometrical features of these 1D polymers are compared with those of the bis(imidazolyl)methane complexes and of the known Btm derivative, Btm(Ph2SnBr2). Interestingly, the expected isomorphous structures for selected couples was not found, as if very subtle energetic differences were driving the crystallization of these species into different structure types.