1,5,9-Tristannacyclododecanes as lewis acids. Novel structure of a chloride complex

Article abstract of DOI:10.1021/om00114a003

A simple procedure for the preparation of substituted 1,5,9-tristannacyclododecanes RRSn-(CH₂)₃SnRR′(CH₂) ₃SnRR(CH₂)₃ {R = R′ = CH₃ (3); R = CH₃, R′ = Cl (4); R = R′ = Cl (5)} is described. Their complexing behavior toward chloride was investigated by means of ¹¹⁹Sn NMR spectroscopy. Both 4 and 5 yielded evidence for complex formation but behaved differently from each other. A complex {(5Cl)(Ph₃P=N=PPh₃)⁺} (6) was isolated; its structure as determined by single-crystal X-ray diffraction shows that 5 acts as a bidentate Lewis acid via unsymmetrical transannular bridging by a chloride ion. 6 crystallizes in the monoclinic space group P2₁/c with the unit-cell dimensions a = 11.691 (2) ?, b = 24.652 (4) ?, c = 17.353 (4) ?, β = 72.70 (1)°, V = 5110.6 ?³, and D(calcd) = 1.65 g/cm^-3 for Z = 4. The structure was refined to a final R value of 0.039 for 4003 independent reflections.