Unsymmetrical Bicentric Organotin Lewis Acids {Me₂N(CH₂)₃}Ph(X)Sn(CH₂)_nSnPh₂X (X = F, I; n = 1, 3): Syntheses and Structures

The syntheses of the intramolecularly coordinated organotin compounds {Me₂N­(CH₂)₃}­Ph­(X)­SnCH₂SnPh₂X (3, X = I; 4, X = F) and {Me₂N­(CH₂)₃}­Ph­(F)­Sn­(CH₂)₃SnPh₂F (7) are reported. The compounds have been characterized by elemental analysis, electrospray mass spectrometry, ¹H,¹H DOSY (4), ¹³C, ¹⁹F, and ¹¹⁹Sn NMR spectroscopy, and single-crystal X-ray diffraction analysis. In the solid state, compound 4 is a head-to-tail dimer as a result of unsymmetrical Sn–F–Sn bridges, whereas compound 7 is a monomer with F→Sn intramolecular coordination, giving a six-membered ring. In solution, both 4 and 7 are monomeric. The reactions of both 4 and 7 with fluoride anion in CD₂Cl₂ have been investigated by variable-temperature ¹⁹F and ¹¹⁹Sn NMR spectroscopy.