SYNTHESIS, CHARACTERIZATION AND CRYSTAL-STRUCTURES OF ISOTHIOCYANATE AND CARBODIIMIDE COMPLEXES DERIVED FROM ORGANOMAGNESIUM REAGENTS - INSERTION INTO MG-X (X=C OR N) BONDS

A series of magnesium-isothiocyanate and -carbodiimide insertion produ cts, Mg(SCPhNBu(t))(2)(thf)(2) 1, Mg(SCPhNPh)(2)(thf)(2) 2, Mg(Pr(1)NC RNPr(1))(2)(thf)(2) (R = Ph 3, Et 4 or Pr-1 5) and Mg(Bu(t)NCEtNBu(t)) (2)(thf)(2) 6 have been prepared by the stoichiometric reaction betwee n MgR(2) (R = Ph, Pt or pr(i)) and vanous isothiocyanates and carbodii mides in tetrahydrofuran (thf) solution. The 1:1 reaction between bis( diisopropylamido)magnesium and 1,3-diisopropylcarbodiimide gave a dinu clear complex Mg-2(mu-NPr2i)(2)[((PrN)-N-i)(2)CNPr2i](2) 7 and a monon uclear complex Mg[((PrN)-N-i)(2)CNPr2i](2)(thf) 8 when the stoichiomet ry is 1:2. The mononuclear complexes Mg[SC(NPh)NR(2)](2)(thf)(2) (R = Pr(i)9 or Et 10) were obtained using phenyl isothiocyanate and bis(die thylamido)- or bis(diisopropylamido)magnesium in 1 : 1 stoichiometric ratio. A plausible mechanism for the formation of 7 and 8 is suggested . Reaction between MgEtBr and PhNCS in diethyl ether gave the dinuclea r complex Mg-2(SCEtNPh)(4)(OEt(2))(2) 11. All-of the complexes were ch aracterized by H-1, C-13 NMR and IR spectroscopy as well as elemental analysis The crystal structures of 1, 3, 8, 9 and 11 were determined b y single-crystal X-ray diffraction. The reaction of complex 1 with an excess of PhNCO resulted in the cyclotrimerization of phenyl isocyanat e to give (PhNCO)(3) . thf.