Formation of the Novel Six-Coordinate Atrane Cation in [FMeSn(HMeNCH(2)CH(2))(2)N(CH(2)CH(2)NMe)]BF(4)

The reaction of the azastannatranes RSn(NMeCH(2)CH(2))(3)N 1 (R = Me), 2 (R = n-Bu), and 3 (R = Ph) with BF(3).Et(2)O in THF gave the novel six-coordinate tin compounds 4-6, respectively, in which BF(3) adds across one of the three covalent Sn-N bonds to give a F-Sn<--NMe(BF(2)) linkage. The tricyclic atrane framework retained in the reaction with BF(3).Et(2)O is preserved under hydrolysis conditions with substoichiometric amounts of water. A hydrolysis product of 4 is the new fluorotin salt [FMeSn(HMeNCH(2)CH(2))(2)N(CH(2)CH(2)NMe)]BF(4) [7(BF(4))] whose structure, determined by X-ray analysis, also features a six-coordinate tin atom. The IR and NMR spectra of 4-6 confirm their six-coordinate nature. The (1)H and (13)C NMR spectra are assigned using COSY, NOESY, and selectively proton decoupled (13)C NMR spectral techniques. Crystallographic parameters for 7(BF(4)) are as follows: triclinic space group P&onemacr;, a = 8.295(2) Å, b = 8.924(2) Å, c = 13.639(2) Å, alpha = 88.59(2) degrees, beta = 74.83(2) degrees, gamma = 79.99(2) degrees, and Z = 2.