Synthesis and structure of [2-(4,4-dimethyl-2-oxazoline)-5-methylphenyl]methylphenyltin bromide. A novel triorganotin halide having a configurationally stable chiral tin center

Reaction of [2-(4,4-dimethyl-2-oxazoline)-5-methylphenyl]copper with dimethyltin dibromide or methylphenyltin dibromide affords [2-(4,4-dimethyl-2-oxazoline)-5-methylphenyl]dimethyltin bromide (1) and [2-(4,4-dimethyl-2-oxazoline)-5-methylphenyl]methylphenyltin bromide (2), respectively. The crystal structure of 2 has been determined by X-ray diffraction methods. C₁₉H₂₂BrNOSn is monoclinic, space group P2_t/a with a = 18.1258(9), b = 11.5704(11), c = 9.5315(6) Å, β = 95.143(6)° and Z = 4, final R = 0.038 for 2760 observed reflections. As a result of intramolecular coordination of the nitrogen atom of the oxazoline ring to the tin atom, the geometry about tin in 1 is trigonal bipyramidal. The carbon ligands are at the equatorial sites, while the more electronegative nitrogen and bromine atoms are at the axial positions. An ¹H NMR spectroscopic study showed that in solution the chiral tin center is configurationally stable up to 120°C )the highest temperature studied).