New zirconium and zirconocene guanidinate complexes

The guanidines (HNi-Pr)2Cdouble bond; length as m-dashNAr (Ar = 4-t-BuC6H41, 4-BrC6H42 and 2,4,6-Me3C6H23) have been used in the synthesis of the lithium salts [Li{i-PrN(HNiPr)Cdouble bond; length as m-dashNAr}(THF)]24–6 and [Li2{(Ni-Pr)2Cdouble bond; length as m-dashNAr}] 7–9. Complexes [Zr{κ2,N,N′-(Ni-Pr)(NAr)CNH(i-Pr)}2Cl2] (Ar = 4-t-BuC6H410, 4-BrC6H411, 2,4,6-Me3C6H212), which contain an asymmetrical monoanionic guanidinate ligand coordinated to the zirconium atom, were obtained by protonolysis of 1–3 in the presence of NEt3 or by a metathesis reaction of 4–6 with ZrCl4. The zirconocene complexes [Zr(η5-C5H5)2{κ2,N,N′-(Ni-Pr)(NAr)CNH(i-Pr)}Cl] (Ar = 4-t-BuC6H413, 4-BrC6H414, 2,4,6-Me3C6H215) and [Zr(η5-C5H5)2{κ2,N,N′-(Ni-Pr)2Cdouble bond; length as m-dashNAr}] (Ar = 4-t-BuC6H416, 4-BrC6H417, 2,4,6-Me3C6H218) were synthesized by metathesis reactions of the corresponding lithium salts and Zr(η5-C5H5)2Cl2. Complexes 16–18 exhibit dynamic behavior in solution and this was studied by variable-temperature NMR experiments. The molecular structures of 4 and 10 were determined by single-crystal X-ray diffraction.