FORMATION OF THE NOVEL 6-COORDINATE ATRANE CATION IN [FMESN(HMENCH2CH2)(2)N(CH2CH2NME)]BF4

The reaction of the azastannatranes RSn(NMeCH2CH2)(3)N 1 (R = Me), 2 ( R = n-Bu), and 3 (R = Ph) with BF3 . Et2O in THF gave the novel six-co ordinate tin compounds 4-6, respectively, in which BF3 adds across one of the three covalent Sn-N bonds to give a F-Sn<--NMe(BF2) linkage. T he tricyclic atrane framework retained in the reaction with BF3 . Et2O is preserved under hydrolysis conditions with substoichiometric amoun ts of water. A hydrolysis product of 4 is the new fluorotin salt [FMeS n(HMeNCH2CH2)(2)N(CH2CH2NMe)]BF4 [7(BF4)] whose structure, determined by X-ray analysis, also features a six-coordinate tin atom. The TR and NMR spectra of 4-6 confirm their six-coordinate nature. The H-1 and C -13 NMR spectra are assigned using COSY, NOESY, and selectively proton decoupled C-13 NMR spectral techniques. Crystallographic parameters f or 7(BF4) are as follows: triclinic space group <P(1)over bar>, a = 8. 295(2) Angstrom, b = 8.924(2) Angstrom, c = 13.639(2) Angstrom, alpha = 88.59(2)degrees, beta = 74.83(2)degrees, gamma = 79.99(2)degrees, an d Z = 2.