Synthesis and spectral properties of iron(II), copper(I), silver(I), and palladium(II) complexes of a bidentate diisonitrile

The diisonitrile (t-BuDisNC) with two thioether sulfurs in the bridging group has been synthesized in six reaction steps from chlorobenzene. The treatment of iron(II) chloride, silver(I) tetrafluoroborate or sodium tetrachloropalladate(II) with t-BuDisNC yields the corresponding complexes, FeCl2(t-BuDisNC)(2), Ag(t-BuDisNC)(2)BF4, PdCl2(t-BuDisNC), whereas the copper(I) complex, Cu(t-BuDisNC)(2)BF4, is prepared by a ligand exchange reaction. As judged by the molar. conductances. and mass spectra of Cu(t-BuDisNC)(2)BF4 and Ag(t-BuDisNC)(2)BF4, the tetrafluoroborate anion is ionized in acetonitrile. The strong band at 2110 cm(-1), which is correlated with the NdropC stretching mode, shifts to higher energy upon the inductive effect of the metal ion. The methylene proton signal in the bridging group is scarcely shifted on metal coordination. These data show that the NdropC group in the complexes serves as a a-donor and the thioether sulfur is not coordinated to the metal atom.