Diorganotin(IV) 4,6-dimethyl-2-pyrimidyl selenolates: synthesis, structures and their utility as molecular precursors for the preparation of SnSe2 nano-sheets and thin films

The complexes of composition [R2Sn{SeC4H(Me-4,6)(2)N-2}(2)] (R = Me, Et, Bu-n or Bu-t) have been isolated by the reaction of R2SnCl2 with NaSeC4H(Me-4,6)(2)N-2. The treatment of [R2Sn{SeC4H(Me-4,6)(2)N-2}(2)] with R2SnCl2 afforded chloro complexes [R2SnCl{SeC4H(Me-4,6)(2)N-2}] (R = Me, Bu-n or Bu-t). These complexes were characterized by elemental analyses and NMR (H-1, C-13, Se-77, Sn-119) spectroscopy. The molecular structures of [(Bu2Sn)-Bu-t{SeC4H(Me-4,6)(2)N-2}(2)] and [(Bu2SnCl)-Bu-t{SeC4H(Me-4,6)(2)N-2}] were established by single crystal X-ray diffraction analyses. Thermolysis of [R2Sn{SeC4H(Me-4,6)(2)N-2}(2)] (R = Et, Bu-n or Bu-t) in oleylamine (OLA) afforded the nanocrystalline hexagonal phase of SnSe2. Thin films of SnSe2 were deposited on silicon wafers by AACVD of [(Bu2Sn)-Bu-t{SeC4H(Me-4,6)(2)N-2}(2)]. The nanostructures and thin films were characterized by solid state diffuse reflectance spectroscopy, XRD, EDX, SEM and TEM techniques. The solid state diffuse reflectance measurements of the nanosheets showed direct and indirect band gaps in the ranges of 1.76-2.30 eV and 1.38-1.49 eV, respectively, which are blue shifted relative to bulk tin selenide.