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

Abstract

The complexes of composition [R₂Sn{SeC₄H(Me-4,6)₂N₂}₂] (R = Me, Et, ⁿBu or ^tBu) have been isolated by the reaction of R₂SnCl₂ with NaSeC₄H(Me-4,6)₂N₂. The treatment of [R₂Sn{SeC₄H(Me-4,6)₂N₂}₂] with R₂SnCl₂ afforded chloro complexes [R₂SnCl{SeC₄H(Me-4,6)₂N₂}] (R = Me, ⁿBu or ^tBu). These complexes were characterized by elemental analyses and NMR (¹H, ¹³C, ⁷⁷Se, ¹¹⁹Sn) spectroscopy. The molecular structures of [^tBu₂Sn{SeC₄H(Me-4,6)₂N₂}₂] and [^tBu₂SnCl{SeC₄H(Me-4,6)₂N₂}] were established by single crystal X-ray diffraction analyses. Thermolysis of [R₂Sn{SeC₄H(Me-4,6)₂N₂}₂] (R = Et, ⁿBu or ^tBu) in oleylamine (OLA) afforded the nanocrystalline hexagonal phase of SnSe₂. Thin films of SnSe₂ were deposited on silicon wafers by AACVD of [^tBu₂Sn{SeC₄H(Me-4,6)₂N₂}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.