Search

A series of asymmetric and potentially bidentate amino alcohols and amino fluoro alcohols (R N OH) having a different number of methyl/trifluoromethyl substituents at the α-carbon atom, [HOC(R 1 )(R 2 )CH 2 NMe 2 ] (R 1 = R 2 = H (dmaeH); R 1 = H, R 2 = CH 3 (dmapH); R 1 = R 2 = CH 3 (dmampH); R 1 = H, R 2 = CF 3 (F-dmapH); R 1 = R 2 = CF 3 (F-dmampH)) have been used to develop new monomeric and heteroleptic tin(IV) amino(fluoro)alkoxides [Sn(OR) 2 (OR N ) 2 ] (R = Et, Pr i , Bu t ). These new complexes, which were thoroughly characterized by spectroscopy (IR and multinuclei NMR ( 1 H, 13 C, 19 F, and 119 Sn)) as well as single-crystal X-ray studies on representative samples, were investigated for their thermal behavior to determine their suitability as MOCVD precursors for the deposition of metal oxide thin films. The two most suitable compounds, [Sn(OBu t ) 2 (dmamp) 2 ] and [Sn(OBu t ) 2 (F-dmamp) 2 ], were used in a direct liquid injection chemical vapor deposition (DLI-CVD) process to deposit undoped SnO 2 and F-doped SnO 2 thin films, respectively, on silicon and quartz substrates. Film growth rates at different temperatures (from 400 to 700 °C), film thickness, crystalline quality, and surface morphology were investigated. The films deposited on quartz showed high transparency (above 80%) in the visible region and low carbon contamination on the surface (11-13% from XPS), which could easily be removed completely with 2 min of Ar + sputtering.

The nanometric mixed tin-titanium oxide doped with a M(5+) cation was recently shown as a promising thermoelectric material. We report here synthesis of novel molecular precursors for above material using a convenient approach of reacting a metal chloride with a metal alkoxide. Heterometallic complexes with simple addition formula [(EtOH)(2)(OEt)(2)Ti(μ-OEt)(2)SnCl(4)] (1·EtOH) and [(EtOH)(OEt)(3)Ta(μ-OEt)(2)SnCl(4)] (2) were isolated in quantitative yield, which on recrystallization from isopropanol afforded mixed-alkoxide complexes [(Pr(i)OH)(2)(OPr(i))(2)Ti(μ-OEt)(2)SnCl(4)] (3) and [(Pr(i)OH)(OPr(i))(3)Ta(μ-OEt)(2)SnCl(4)] (4), respectively, thus indicating the robustness of the heterometallic M(μ-OEt)(2)Sn core in the solution phase. Facile conversion of these precursors to halide-free spinodal form of Ta(5+)-doped TiO(2)-SnO(2) as a potential thermoelectric material is reported.