Synthesis and structural studies on dimeric organotin cations

Novel dimeric organotin cations [R2SnOH(OTf)(H2O)](2) (R = n-Bu, t-Bu, and 2-phenylbutyl; Tf = CF3SO2) were synthesized from R2SnO and TfOH. The structures of these compounds were investigated by single-crystal X-ray analysis and solid-state Sn-119 NMR in the solid state and Sn-119 NMR spectra together with electrical conductivity measurements in solution. tert-Butyltin and 2-phenylbutyltin derivatives have cationic structures both in the solid state and in solution. The n-butyltin derivative is nonionic in the solid state but dissociates into ionic species in solution. The H2O molecule in this compound can be readily replaced by hexamethylphosphoric triamide (HMPA); the resulting adduct has a similar structure. The corresponding nitrate has a nonionic dimeric structure with bidentate nitrate coordination, [t-Bu2SnOH(NO3)](2). As such, it is concluded that both bulky alkyl groups attached on tin and electronegative ligands such as triflate are crucial for generation of the cationic species.