Preparation and characterisation of anionic bis(cyclopentadienyl)niobium complexes: molecular structure of [K(18-crown-6)][Nb(η-C5H5)2(SnMe3)2]

TLDR: In this article, structural and spectroscopic evidence is presented for the presence of Nb-H-M interactions, where M = Li, Na or K. The X-ray crystal structure of 11 shows there are two separate ions [Nb(η-C5H5)2(SnMe3)2]− and [K(18crown-6)]+ with no close interionic contacts.

Abstract: The reaction between [Nb(η-C5H5)2H3] and LiBu, LiBu-1,4,7,10-tetraoxacyclododecane(12-crown-4), NaH–1,4,7,10,13-pentaoxacyclopentadecane(15-crown-5), KH-1,4,7,10,13,16-hexaoxacyclo-octadecane(18-crown-6), or NaNH2 gives M[Nb(η-C5H5)2H2](M = Li, 1; or Na, 5) and [M(crown)][Nb(η-C5H5)2H2][M(crown)= Li(12-crown-4)2, Na(15-crown-5)3 or K(18-crown-6)4]. The compound SnMe3Cl reacts with 1 or 4 to give [Nb(η-C5H5)2H2(SnMe3)]. The hydrides [Nb(η-C5H5)2H2(SnMe3)] and [Nb(η-C5H5)2H(SnMe3)2] react with LiBu–12-crown-4, NaNH2–15-crown-5 and KH–18-crown-6 to give [M(crown)][Nb(η-C5H5)2H(SnMe3)][M(crown)= Li(12-crown-4), Na(15-crown-5)7 or K(18-crown-6)8] and [M(crown)][Nb(η-C5H5)2(SnMe3)2][M(crown)= Li(12-crown-4)9, Na(15-crown-5)10 or K(18-crown-6)11], respectively. The X-ray crystal structure of 11 shows there to be two separate ions [Nb(η-C5H5)2(SnMe3)2]– and [K(18-crown-6)]+ with no close interionic contacts. Structural and spectroscopic evidence is presented for the presence of Nb–H–M interactions, where M = Li, Na or K.