Diorganotin(iv) 2-pyridyl and 2-pyrimidyl thiolates: synthesis, structures and their utility as molecular precursors for the preparation of tin sulfide nanosheets

Abstract

The complexes of composition, [R₂Sn(2-SC₅H₄N)₂] (R = Me (1) or Et (2)), [Et₂SnCl(2-SC₅H₄N)] (3) and [R₂SnCl{SC₄H(Me-4,6)₂N₂}] (R = Me (4), Et (5)) were prepared and characterized by elemental analyses and NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy. The molecular structures of [Et₂Sn(2-SC₅H₄N)₂] (2), [Me₂SnCl{SC₄H(Me-4,6)₂N₂}] (4) and [Et₂SnCl{SC₄H(Me-4,6)₂N₂}] (5) were established unambiguously by single crystal X-ray diffraction analyses. The central tin atom acquires a skew trapezoidal bipyramidal configuration in the former (2) while distorted trigonal bipyramidal geometry in the latter two complexes (4 and 5), respectively. Thermolysis of diethyltin complexes [Et₂Sn(2-SC₅H₄N)₂] (2) and [Et₂SnCl{SC₄H(Me-4,6)₂N₂}] (5) in oleylamine (OLA) afforded orthorhombic phase SnS nano-sheets of thickness 30–80 nm which 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 1.61–1.90 eV and 1.46 eV, respectively which are blue shifted relative to bulk tin sulfide [E_g (direct) = 1.3 eV and E_g (indirect) = 1.1 eV].