Chalcogenoether complexes of Nb(v) thio- and seleno-halides as single source precursors for low pressure chemical vapour deposition of NbS 2 and NbSe 2 thin films.

NbSCl3 was obtained via reaction of NbCl5 with S(SiMe3 )2 in anhydrous CH2 Cl2 , whilst in MeCN solution the same reaction gives [NbSCl3 (MeCN)2 ]. [NbSeCl3 (MeCN)2 ] was obtained similarly from NbCl5 with Se(SiMe3 )2 . The chalcogenoether complexes, [NbSCl3 (ER2 )] (E = S: R = Me,n Bu; E = Se: R =n Bu), were obtained from reaction of NbCl5 , ER2 and S(SiMe3 )2 in CH2 Cl2 . The structure of the [Nb2 S2 Cl6 (SMe2 )2 ] reveals a Cl-bridged dimer with the SMe2 ligands disposed syn. The Cl bridges are highly asymmetric, with the long Nb-Cl bond trans Nb[double bond, length as m-dash]S. The complexes, [NbSCl3 (L-L)] (L-L = MeSCH2 CH2 SMe, MeS(CH2 )3 SMe,i PrSCH2 CH2 Si Pr, MeSe(CH2 )3 SeMe andn BuS(CH2 )3 Sn Bu), were obtained from reaction of L-L with preformed [NbSCl3 (MeCN)2 ]. The structures of the Me-substituted complexes reveal distorted octahedral monomers with the neutral ligands trans to S/Cl. Solution1 H and77 Se{1 H} NMR data showed that the neutral ligands are partially dissociated and undergoing fast exchange at ambient temperatures in CH2 Cl2 solution, consistent with weak Lewis acidity for NbSCl3 . The complexes containingn Bu-substituted ligands have been used as single source precursors for low pressure chemical vapour deposition (CVD) of 3R-NbS2 thin films. 2H-NbSe2 thin films were also obtained via low pressure CVD using [NbSe2 Cl3 (Sen Bu2 )]. The thin films were characterised by grazing incidence and in-plane XRD, pole figure analysis, scanning electron microscopy and energy dispersive X-ray analysis.