Structural and Mechanistic Studies of Halogenation of a Tin(II) N-Functionalized Alkyl

The halogenation of the tin(II) alkyl SnR 1 2 ( 1 ) [R 1 = CH(SiMe 3 )C 9 H 6 N-8] to give R 1 2 SnX 2 [X = F ( 2 ), Cl ( 3 ), Br ( 4 ), I ( 5 )] was investigated by reacting 1 with SnX 2 (X = F, Cl, Br, and I), PbCl 2, BCl 3, and X 2 (X = Br, I), respectively. 1 H, 119 Sn NMR and X-ray analysis showed that the reactions with SnX 2 under a milder experimental condition afforded intermediate compounds, R 1 2 Sn→SnX 2 [X = Cl ( 6 ), Br ( 7 )] and R 1 SnX [X = Cl ( 8 ), Br ( 9 )]. Further heating gave the final products R 2 SnX 2 . The X-ray structures of 2 − 6 and 9 have been determined. The dynamic exchange process between diastereoisomers of R 1 SnX (X = Cl, Br) has been studied by variable-temperature 1 H and 119 Sn NMR spectroscopy.