Synthesis, characterisation and structural studies of amidinate and guanidinate alkaline earth–transition metal bonded complexes
Reaction of magnesium amidinate complexes of the form [{MesC(NR)2}MgBr(OEt2)]2(R?=?iPr, Dipp, Mes) with the potassium salts of transition metal anions K[CpFe(CO)2] (K[Fp]) and K[Co(CO)3(PCy3)](THF)2gave the complexes {MesC(NR)2}MgFp(THF) and {MesC(NR)2}Mg{Co(CO)3(PCy3)}(THF). Single crystal X-ray diffraction studies of {MesC(NR)2}Mg{Co(CO)3(PCy3)}(THF) for R?=?iPr and Dipp confirm these to have Mg–Co bonds in the solid state. Reaction of the structurally similar magnesium guanidinate complex {Me2NC(NDipp)2}MgI(OEt2) with the aforementioned transition metal anions or K[Co(CO)3(PPh3)](THF) gave the series of complexes [{Me2NC(NDipp)2}MgFp]2, {Me2NC(NDipp)2}Mg{Co(CO)3(PCy3)}(OEt2) and {Me2NC(NDipp)2}Mg{Co(CO)3(PPh3)}(OEt2). Structural authentication by X-ray crystallography showed [{Me2NC(NDipp)2}MgFp]2to be a very rare example of a base-free alkaline earth–transition bonded complex, having two Mg–Fe bonds. IR and diffusion NMR spectroscopy was carried out to gain further insight into the solid state and solution phase structures.
Green, Ross,Walker, Alicia C.,Blake, Matthew P.,Mountford, Philip