Niobium(V) Alkoxides. Synthesis, Structure, and Characterization of [Nb(μ-OCH2CH3)(OCH2C(CH3)3)4]2, {[H3CC(CH2O)(CH2-μ-O)(C(O)2)]Nb2(μ-O)(OCH2CH3)5}2, and {[H3CC(CH2O)2(CH2-μ-O)]Nb(OCH2CH3)2}2 for Production of Mixed Metal Oxide Thin Films1

We have synthesized and isolated a number of unique niobium alkoxide compounds and introduced them into novel solution processes for the production of lead magnesium niobate oxide (PMN) and niobium-doped lead zirconate titanate oxide (PNZT) materials. A more sterically demanding analogue to Nb(OEt) 5 (Et = CH 2 CH 3 ) was isolated as [Nb(μ-OEt)(ONp) 4 ] 2 ( 1, Np = CH 2 C(CH 3 ) 3 ) by alcoholysis exchange. 1 crystallized in an edge-shared bioctahedral dinuclear arrangement with the smaller ligands acting as the bridging moieties. Multidentate ligands such as bis(hydroxymethyl)propionic acid (BHMP−H 3 ) and tris(hydroxymethyl)ethane (THME−H 3 ) were independently reacted with Nb(OEt) 5 to reduce the number of terminal ligands, yielding [(μ-BHMP)Nb 2 (μ-O)(OEt) 5 ] 2 ( 2 ) and [(μ-THME)Nb(OEt) 2 ] 2 ( 3 ) respectively. For 2, two unsymmetrical “(EtO) 2 Nb(μ-O)Nb(OEt) 3 ” units are bridged by two tetradentate BHMP ligands. The THME moiety of 3 acts as a chelating, unidentate-bridging ligand forming a symmetrical dinuclear species, wherein each Nb atom possesses two terminal ethoxides. The synthesis, characterization, structural aspects, and solution properties of 1 − 3 are reported. The resulting morphological and electrical changes in the properties of the resulting electroceramic PMN and PNZT films due to the incorporation of these Nb alkoxides are also reported.