Tin(IV) and organotin(IV) complexes containing mono- or bidentate N-donor ligands. IV. 2-Methyl, 2-isopropyl- and 4-methyl-imidazole derivatives: synthesis, characterization and behavior in solution

The interaction between 4-methyl-, 2-methyl- and 2-isopropyl-imidazole, L1, L2 and L3 respectively (L in general), and several tin(IV) and organotin(IV) acceptors in diethyl ether, acetonitrile, dichloromethane or chloroform, gives 1:1 [(L1)(C6H5)3SnCl] · 1/3H2O, [(L3)(C6H5)3SnCl], [(L3)(CH3)3SnCl] and [(L3)(6H5)2SnCl2] · (H2O), 2:1 [(L)2RnSnX4−n] · zH2O (L = L1, R = Me, n = 1, 2 or 3, X = Cl, z = 0 or 6; L = L1, R = Me, n = 2, X = Br or I, z = 0; L = L1, R = Et, n = 2, X = Cl or Br, z = 0; L = L1, R = Bun, n = 2 or 3, X = Cl or Br, z = 0; L = L1, R = Ph, n = 2, X = Cl, z = 1; L = L2, R = Me, n = 2 or 3, X = Cl, z = 0 or 1; L = L2, R = Bun or Ph, n = 1, X = Cl, z = 2 or 3; L = L3, R = Me, n = 2, z = 1) and 3:1 (L1)3RSnCl3 (R = Bun or Ph) adducts. The derivative [(L1)2(CH3)2SnCl2] reacts with AgNO3 and NaBPh4 in ethanol and diethyl ether giving the complexes [(L1)2(CH3)2Sn(NO3)2] · H2O and [(L1)4(CH3)2Sn](BPh4)2 respectively. The compounds were characterized by analytical and spectral data. The behavior in solution was investigated by conductivity, molecular weight determinations, 1H, 119Sn and ROESY NMR experiments. The triorganotin(IV) derivatives dissociate in chloroform and in acetone solution, the diorganotin(IV) derivatives dissociate only partly and the monoorganotin(IV) complexes probably retain the hexacoordinate configuration. The derivatives [(L1)2(CH3)2SnX2] (X = Cl or Br) react with 1,10-phenanthroline (Phen), yielding immediately the chelate adducts [(Phen)(CH3)2SnX2], upon complete displacement of the azole ligand, whereas the less basic 2-benzoylpyridine and the P-donors monodentate PR3 (R = phenyl, benzyl or cyclohexyl) or bidentate [PPh2CH2]2, are not able to displace the imidazole from the tin center.