Synthesis of tin oxide precursors and related germanium and lead compounds

The goals of this study were to synthesize volatile tin(II) hexafluoroisopropoxide complexes for use as precursors to tin oxide or fluorine-doped tin oxide and to prepare related germanium(II) and lead(II) compounds. M(N(SiMe(3))(2))2 reacts with 2 equiv of R(f)OH (R(f) = CH(CF3)(2)) and 1 equiv of added amine, L, to give M(OR(f))(2)L (M = Ge, L py or H(2)NPh; M = Sn, L = HNMe(2) or py; M = Pb, L p-pyNMe(2)) in high yield. Alternatively, Sn(OR(f))(2)(HNMe(2)) can be prepared by reacting Sn(NMe(2))(2) with R(f)OH. X-ray crystallographic studies of Ge(OR(f))(2)(H(2)NPh) and Sn(OR(f))(HNMe(2)) show they are monomers with trigonal pyramidal geometries. An X-ray structure of the Pb compound shows it is the dimer [Pb(mu-OR(f))(OR(f))(p-pyNMe(2))](2). Pb(NMe(2))(2) reacts with 3 equiv of R(f)OH to give [Me(2)NH(2)][Pb(OR(f))(3)], which an X-ray structure shows is the dimer {[Me(2)NH(2)][Pb(mu-OR(f))(OR(f))(2)]}(2). Both Pb dimers are held together by weak dative Pb-O interactions. Sn(N(SiMe(3))(2))(2) reacts with 2 equiv of R(f)OH in the absence of added amine to give amine-free Sn(OR(f))(2). By analogy to known tin(II) alkoxide and related compounds, Sn(OR(f))2 is proposed to be a dimer with two bridging alkoxide ligands. The tin compounds are volatile solids, an important criterion for their possible use as conventional tin oxide precursors in chemical vapor deposition processes.