Syntheses and Structures of Diorganotin Compounds Containing a Pentadentate Schiff Base Featuring Two Chiral Centers

A pentadentate Schiff base pro-ligand, suitable for the generation of metal complexes containing two chiral centers, is synthesized. The pro-ligand H₂L^Me is reacted with diorganotin precursors to yield the tin compounds [Me₂Sn(L^Me)] (1), [n-Bu₂Sn(L^Me)] (2), [t-Bu₂Sn(L^Me)] (3), [Bn₂Sn(L^Me)] (4), and [n-Oct₂Sn(L^Me)] (5), where L^Me = N-[(E)-1-[6-[(E)-N-(p-tolylsulfonamido)-C-methylcarbonimidoyl]pyridin-2-yl]ethylideneamino]-p-tolylsulfonamide. Characterization in solution (NMR spectroscopy and high-resolution mass spectrometry) and solid state (Fourier transform infrared spectroscopy and single crystal X-ray diffraction analysis) confirms for each compound a seven-coordinate C₂SnN₃O₂ environment with pentagonal-bipyramidal geometry. The ¹¹⁹Sn NMR spectra exhibit high field-shifted signals, consistent with seven coordinated diorganotin Schiff base derivatives. In the solid state, the S(O)C₆H₄Me moieties in 1–4 are mutually anti-oriented, resulting in molecular topologies similar to those found in Jacobsen's catalyst. In addition to van der Waals interactions, the molecular arrangements in the 3D solid-state structures are primarily controlled by CH⋯O hydrogen bonds, along with CH⋯N, CH⋯π, and π⋯π interactions giving macrocyclic or cage-type assemblies.