Attempts to synthesize titanium(IV) neopentoxide led to two unique products which were crystallographically characterized. A metathesis reaction between TiCl(4) and NaOCH(2)CMe(3) (NaONp) yielded Ti(3)(O)(Cl)(ONp)(9).C(7)H(8), 1, which adopts a standard M(3)(&mgr;(3)-X)(2)(&mgr;-X)(3)X(6) structure. The &mgr;(3) ligands are a Cl and an O atom, with the rest of ligands represented by bridging and terminal ONp ligands. [Ti(ONp)(4)](2), 2, was isolated in high yield by an alcoholysis exchange between Ti(OPr(i))(4) and HONp. 2 adopts a typical M(2)(&mgr;-X)(2)(X)(6) fused axial-equatorial edge-shared geometry, wherein each metal center is 5 coordinated. On the basis of molecular weight solution studies and (1)H, (13)C, (17)O (natural abundance), and (47,49)Ti solution and solid-state NMR investigations, 2 was determined to be a monomer in solution.

Reactions of titanium(IV) neopentoxide, [Ti(μ-Oneo-Pe)(Oneo-Pe)3]2 (1, Oneo-Pe = OCH2CMe3), with alkali neopentoxides (AOneo-Pe) resulted in the isolation of the dimeric complexes [ATi(Oneo-Pe)5]2 [A = Li (2), Na (3), and K (4)], independent of the alkali metal investigated. Each compound was characterized by solution and solid-state multinuclear NMR, isopiestic molecular weight determination, and/or single-crystal X-ray diffraction. In the solid state, both 2 and 4 were found to adopt a standard [MM‘(OR)5]2 arrangement, wherein the Ti metals are in a distorted trigonal-bipyramidal geometry and each alkali metal center is four-coordinated. Suitable crystals of 3 were not isolated, but solid-state MAS (17O, 13C, x A) NMR spectroscopy indicated that the solid-state structure of 3 was consistent with its congeners. Multinuclear (1H, 7Li, 13C, 17O, 23Na) solution NMR spectroscopy data in toluene revealed that 2 exists in a complex multinuclear equilibrium, whereas 3 and 4 exist as mononuclear species in solution.

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 = CH2CH3) was isolated as [Nb(μ-OEt)(ONp)4]2 (1, Np = CH2C(CH3)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−H3) and tris(hydroxymethyl)ethane (THME−H3) were independently reacted with Nb(OEt)5 to reduce the number of terminal ligands, yielding [(μ-BHMP)Nb2(μ-O)(OEt)5]2 (2) and [(μ-THME)Nb(OEt)2]2 (3) respectively. For 2, two unsymmetrical “(EtO)2Nb(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.

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