Reactions of secondary silanes with biguanide bases: synthesis and characterization of oligomeric 1,4-bis(silyl)biguanides and 1-alkyl-2,5-bis(silyl)biguanides

The reactions between diorganosilanes, R1R2SiH2 (R1 = Ph, R2 = Ph or Me), and biguanide, 1-propylbiguanide or 1-cyclohexylbiguanide proceed via SiH/NH dehydrocoupling to afford the corresponding oligomeric 1,4-bis(silyl)biguanides (1, 4) and 1-alkyl-2,5-bis(silyl)biguanides (2, 3, 5) with the general formula [R1R2SiNHC(NH)NC(NHSiR1R2H)NR3]n {where R1 = R2 = Ph; R3 = H (1), Prn (2) or Cy (3). R1 = Me, R2 = Ph; R3 = H (4) or Prn (5)}. These have been characterized by GPC, FAB mass, IR, multinuclear (1H, 13C, 29Si) NMR data as well as TGA. The IR and NMR spectra suggest the presence of different conformers in these compounds.