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

The niobium eta -cyclopentadienyl compounds with imido and amido ligands [N b(eta -C5H5)((NBu)-Bu-t)((NHBu)-Bu-t)Cl] 1,* [Nb(eta -C5H5)((NBu)-Bu-t)((NH Bu)-Bu-t)Bu-n] 2, [Nb(eta -C5H5)((NBu)-Bu-t)((NHBu)-Bu-t)(2)] 3, [Nb(eta -C 5H5)((NBu)-Bu-t)((NHBu)-Bu-t)Me] 4, [Nb(eta -C5H5)(eta (1)-C5H5)((NBu)-Bu-t )((NHBu)-Bu-t)] 5, [Nb{(eta -C5H4)CMe2(eta (1)-C5H4)}((NBu)-Bu-t)((NHBu)-Bu -t)] 6, [Nb(eta -C5H5){N((C6H3Pr2)-Pr-i-2,6)}((NHBu)-Bu-t)Cl] 7,* [Nb(eta - C5H5){N((C6H3Pr2)-Pr-i-2,6)}((NHBu)-Bu-t)Me] 8, [Nb(eta -C5H5)((NBu)-Bu-t)( NEt2)Cl] 9 and [Nb(eta -C5H5)((NBu)-Bu-t)((NHBu)-Bu-t)(NEt2)] 10 have been prepared (* indicates the crystal structure has been determined). A correla tion between the chemical shift of the NH proton and the value of Delta del ta measured between the alpha and beta carbons of the tert-butyl groups of the amido ligands is discussed in relation to the degree of electron donati on from the amido ligand to the niobium centre.