The Synthesis of Quinoline-based Tin Complexes with Pendant Schiff Bases

Abstract

Whilst pursuing the synthetic utility of quinoline-based tin complexes, Me 2 Sn(Quin-NO 2 ) 2 (1) and Ph 2 Sn(Quin-NO 2 ) 2 (2) (Quin-NO 2 = 5-nitroquinolino-8-oate) were synthesized bearing coordinatively inert nitro groups. Conventional reduction methodologies successfully converted 1 to Me 2 Sn(Quin-NH 2 ) 2 (3) and 2 to Ph 2 Sn(Quin-NH 2 ) 2 (4) (Quin-NH 2 = 5-aminoquinolino-8-oate). The synthetically useful amine groups proved difficult to exploit in the presence of the central tin atom, however, a complete Schiff base functionalized Sn complex of the dimethyltin pro-ligand Me 2 Sn(Quin-py) 2 (6) was successfully synthesized from 5-[(pyridin-2-ylmethylene)amino]quinolin-8-ol (HQuin-py; 5) in good yield via an alternative strategy exploiting the oxophilic tendencies of tin. All species were fully characterized by NMR (including 119 Sn NMR spectroscopy), HR-ESI MS and single-crystal X-ray diffraction, and preliminary studies of their supramolecular potential are also discussed.