Niobium η-cyclopentadienyl compounds with imido and amido ligands derived from tert-butylamine

Abstract

The niobium η-cyclopentadienyl compounds with imido and amido ligands [Nb(η-C₅H₅)(N^tBu)(NH^tBu)Cl] 1,* [Nb(η-C₅H₅)(N^tBu)(NH^tBu)ⁿBu] 2, [Nb(η-C₅H₅)(N^tBu)(NH^tBu)₂] 3, [Nb(η-C₅H₅)(N^tBu)(NH^tBu)Me] 4, [Nb(η-C₅H₅)(η¹-C₅H₅)(N^tBu)(NH^tBu)] 5, [Nb{(η-C₅H₄)CMe₂(η¹-C₅H₄)}(N^tBu)(NH^tBu)] 6, [Nb(η-C₅H₅){N(C₆H₃ⁱPr₂-2,6)}(NH^tBu)Cl] 7,* [Nb(η-C₅H₅){N(C₆H₃ⁱPr₂-2,6)}(NH^tBu)Me] 8, [Nb(η-C₅H₅)(N^tBu)(NEt₂)Cl] 9 and [Nb(η-C₅H₅)(N^tBu)(NH^tBu)(NEt₂)] 10 have been prepared (* indicates the crystal structure has been determined). A correlation between the chemical shift of the NH proton and the value of Δδ measured between the α and β carbons of the tert-butyl groups of the amido ligands is discussed in relation to the degree of electron donation from the amido ligand to the niobium centre.