Synthesis and properties of MoCl complexes with thio- and seleno-ethers and their use for chemical vapour deposition of MoSe and MoS films.

Treatment of trans-[MoCl(MeCN)] with L (L = MeS, MeSe, THT, ½MeSCHCHSMe) in CHCl solution, or reaction of MoCl with excess L' (L' = BuS, BuSe, ½MeSCHCHSMe, ½PrSCHCHSPr, ½MeSCHCHCHSMe, ½MeSeCHCHCHSeMe) in MeCN, produces the Mo(iv) complexes, [MoCl(L)] and [MoCl(L')], respectively, in good yield. The new complexes have been characterised by IR and UV-vis spectroscopy, elemental analysis and magnetic measurements, whilst crystal structure analyses of trans-[MoCl(MeS)], cis-[MoCl{RS(CH)SR}] (R = Me, Pr) and cis-[MoCl{MeS(CH)SMe}] confirmed their identities and distorted octahedral geometries. The potential of [MoCl(BuE)] (E = S, Se) as the first examples of molybdenum halide derived single source CVD precursors for the growth of MoE thin films was first probed by TGA, which showed multi-step decomposition processes, with the masses of the final residues consistent with MoSe (E = Se) and MoCl (E = S), respectively. Low pressure CVD experiments conducted at 750 °C (E = S) and 525 °C (E = Se) gave silvery and golden yellow films, respectively. Grazing incidence and in plane XRD data confirmed these to be 2H-MoE, whilst the texture of the MoSe was investigated using pole figure measurements. SEM and EDX data, optical and Raman data on the films are also reported.