Adducts of Titanium Tetrachloride with Alkylselenium Compounds:  Molecular Precursors to Titanium Diselenide Films

Abstract

Treatment of titanium tetrachloride (2 equiv) with dimethyl diselenide or diethyl diselenide (1 equiv) in hexane at 0 degrees C, followed by crystallization at -20 degrees C, afforded (TiCl(4))(2)(Se(2)(CH(3))(2)) (78%) and (TiCl(4))(2)(Se(2)(CH(2)CH(3))(2)) (63%), respectively, as red and orange crystalline solids. (TiCl(4))(2)(Se(2)(CH(2)CH(3))(2)) is stable in solution and in the solid state at 23 degrees C, but (TiCl(4))(2)(Se(2)(CH(3))(2)) decomposes to TiCl(4)(Se(CH(3))(2))(2), gray selenium, and other products upon standing in hexane solution, in the solid state, or upon sublimation at 250 degrees C. Treatment of titanium tetrachloride with 2 equiv of dimethyl selenide or diethyl selenide in hexane at ambient temperature afforded a spectroscopically pure brick red solid of TiCl(4)(Se(CH(3))(2))(2) (96%) or TiCl(4)(Se(CH(2)CH(3))(2))(2) (96%), respectively. X-ray crystal structures of (TiCl(4))(2)(Se(2)(CH(2)CH(3))(2)), TiCl(4)(Se(CH(3))(2))(2), and TiCl(4)(Se(CH(2)CH(3))(2))(2) were determined to establish solid state nuclearities. (TiCl(4))(2)(Se(2)(CH(2)CH(3))(2)) crystallizes in the hexagonal space group P3(1)21 with a = 12.106(1) Å, c = 10.786(1) Å, V = 1368.8(4) Å(3), and Z = 3. TiCl(4)(Se(CH(3))(2))(2) crystallizes in the monoclinic space group P2(1)/n with a = 8.175(1) Å, b = 13.051(1) Å, c = 16.871(3) Å, beta = 102.675(8) degrees, V = 1756.3(2) Å(3), and Z = 4. TiCl(4)(Se(CH(2)CH(3))(2))(2) crystallizes in the monoclinic space group P2(1)/n with a = 6.404(4) Å, b = 16.376(7) Å, c = 13.058(8) Å, beta = 101.45(4) degrees, V = 1342(1) Å(3), and Z = 4. TiCl(4)(Se(CH(3))(2))(2) and TiCl(4)(Se(CH(2)CH(3))(2))(2) were evaluated as precursors to titanium diselenide films. TiCl(4)(Se(CH(3))(2))(2) was not a good precursor, but TiCl(4)(Se(CH(2)CH(3))(2))(2) afforded rose-bronze colored titanium diselenide films at substrate temperatures of 500-600 degrees C. The films were characterized by X-ray powder diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. Surprisingly, titanium diselenide films prepared from TiCl(4)(Se(CH(2)CH(3))(2))(2) are moisture sensitive and are apparently hydrolyzed by ambient moisture to titanium dioxide and hydrogen selenide. The relevance of the coordination chemistry to the development of precursors to titanium diselenide films is discussed.

Dinuclear niobium(III), tantalum(III) and tantalum(IV) complexes with thioether and selenoether ligands

“…Complexes of dimethylchalcogenides are not well suited as CVD reagents, because they lack the -hydride decomposition route [11,12,13], and hence the new complexes [M2Cl4( n Bu2S)2(μ-Cl)2(μ-n Bu2S)] were prepared by an analogous method (Scheme 1). X-Ray structures of both complexes were determined (Figures 1 and 2) which showed them to be isomorphous and confirmed the expected confacial bioctahedral geometries, as found for the Me2S complexes [15,17], and the corresponding bond lengths and angles are not significantly different.…”

“…Production of thin films by exfoliation of bulk samples [8] or chemical vapour deposition (CVD) from either single or dual source precursors [9][10][11][12], are current methods of choice. Single source CVD reagents minimise the quantity of reagent needed and potentially offer better control over the composition and film thickness, but reagents suitable for deposition of the heavier analogues (E = Se or Te) are rare [11,12].…”

Atmospheric Pressure CVD of TiSe2 Thin Films on Glass

“…Several reports have detailed the deposition of TiSe 2 films, but only one of them describes a CVD process for the fabrication of these films. [13] McKarns et al have prepared volatile compounds containing titanium and selenium which when employed as a single source precursor lead to TiSe 2 deposition.…”

Accessing new 2D semiconductors with optical band gap: synthesis of iron-intercalated titanium diselenide thin films via LPCVD

“…19,[26][27][28][29] The work presented herein explores the capability of our precursors to generate high quality thin lms of iron-doped titanium selenide, with the objective to achieve desired optical and electrical properties. …”