Heterobimetallic Bismuth−Transition Metal Salicylate Complexes as Molecular Precursors for Ferroelectric Materials. Synthesis and Structure of Bi₂M₂(sal)₄(Hsal)₄(OR) ₄ (M = Nb, Ta; R = CH₂CH₃, CH(CH₃)₂), Bi₂Ti₃(sal)₈(Hsal)₂, and Bi₂Ti₄(OⁱPr)(sal)₁₀(Hsal) (sal = O₂CC₆H₄-2-O; Hsal = O₂

Abstract

The reactions between triphenylbismuth, salicylic acid, and the metal alkoxides M(OCH(2)CH(3))(5) (M = Nb, Ta) or Ti[OCH(CH(3))(2)](4) have been investigated under different reaction conditions and in different stoichiometries. Six novel heterobimetallic bismuth alkoxy-carboxylate complexes have been synthesized in good yield as crystalline solids. These include Bi(2)M(2)(sal)(4)(Hsal)(4)(OR)(4) (M = Nb, Ta; R = CH(2)CH(3), CH(CH(3))(2)), Bi(2)Ti(3)(sal)(8)(Hsal)(2), and Bi(2)Ti(4)(O(i)Pr)(sal)(10)(Hsal) (sal = O(2)CC(6)H(4)-2-O; Hsal = O(2)CC(6)H(4)-2-OH). The complexes have been characterized spectroscopically and by single-crystal X-ray diffraction. Compounds of the group V transition metals contain metal ratios appropriate for precursors of ferroelectric materials. The molecules exhibit excellent solubility in common organic solvents and good stability against unwanted hydrolysis. The nature of the thermal decomposition of the complexes has been explored by thermogravimetric analysis and powder X-ray diffraction. We have shown that the complexes are converted to the corresponding oxide by heating in an oxygen atmosphere at 500 degrees C. The mass loss of the complexes, as indicated by thermogravimetric analysis, and the resulting unit cell parameters of the oxides are consistent with the formation of the desired heterobimetallic oxide. The complexes decomposed to form the bismuth-rich phases Bi(4)Ti(3)O(12) and Bi(5)Nb(3)O(15) as well as the expected oxides BiMO(4) (M = Nb, Ta) and Bi(2)Ti(4)O(11).

Polynuclear Bismuth‐Oxo Clusters: Insight into the Formation Process of a Metal Oxide

“…The Compound 2 crystallises in the triclinic space group P1 with the lattice constants a = 17.0337 (9), b = 19.5750 (14) (5) and g = 66.020(4)8; compound 7·2 C 7 H 8 crystallises in the triclinic space group P1 with the lattice constants a = 14.8295 (12), b = 16.1523 (13), c = 18.4166 (17) , a = 75.960(4), b = 79.112(4) and g = 63.789(4)8; and compound 8·3 C 7 H 8 crystallises in the triclinic space group P1 with the lattice constants a = 17.2915 (14), b =films, [2,14,17,18] wet chemical approaches towards bismuth-containing materials such as the sol-gel process have found broader application. [3,9,19,20] The sol-gel process offers several advantages, such as mild processing temperatures and aggregation of molecular precursors in solution prior to formation of the final material. This approach gives access to thermodynamically stable as well as metastable compounds and favours the formation of homogeneous products.…”

“…The high potential of single-source precursors has motivated several research groups to investigate the reactivity and the structural chemistry of heterometallic bismuth precursors in order to obtain more information on how to control the composition and morphology of the final material at the molecular level. [4,7,[20][21][22][23][24][25][26] Following this strategy, simple bismuth alkoxides, which have been reported previously but have not attracted considerable interest until recently, [17,25,[27][28][29] represent potential starting materials for heterometallic singlesource precursors such as [BiTi 2 (m 3 -O)(m 3 -OiPr) 4 (OiPr) 5 ]. [30] Alkoxide ligands at the periphery of the metal-oxo alkoxides offer the potential for further aggregation through hydrolysis/condensation reactions.…”

“…As a result of steric constraints, polynuclear bismuth-oxo alkoxides such as [Bi 8 (m 4 -O) 2 (m 3 -O) 2 (m-OC 6 F 5 ) 16 ] [23] and [Bi 9 (m 3 -O) 7 (m 3 -OR)(OR) 12 ] (R = C 6 F 5 , 2,6-C 6 H 3 Cl 2 ) [23,31,32] are among the largest bismuth-oxo alkoxides reported to date and the formation of larger aggregates with sterically hindered ligands seems unlikely. Addition of auxiliary ligands is one strategy towards larger multimetallic compounds such as [Bi 8 Ti 8 (sal) 20 (m-OiPr) 8 (OiPr) 8 ] (sal = salicylate), [24] which also show a reduced reactivity of the metal alkoxide bonds. [21] Similarly, replacing alkoxides by silanolate ligands might be expected to slow down the hydrolysis reaction and reduce the tendency for aggregation through intermolecular M···OR bonds to give poorly soluble coordination polymers.…”

Synthesis, spectroscopic and X‐ray single‐crystal structure study of bis(2‐methoxy‐ethanolato)‐bis(8‐quinolinato)titanium(IV)

“…Titanium(IV) tetraisopropoxide, 2-methoxyethanol, 2-ethoxyethanol and 8-hydroxyquinoline were purchased from Fluka and used without further purification. Both Ti(OCH 2 4 Si in ppm) using a Bruker DRX-500 spectrometer. The mass spectroscopy was performed on a Varian Matt 44 instrument (electron impact, 20 eV) and UV-Vis spectra were recorded on a Shimadzo 2100 spectrophotometer.…”

“…8,9 Apparently, the hydrolytic stability of metal alkoxides increases on replacing the number of alkoxy groups with other ligands, and consequently their alkoxy character vanishes; this means that their hydrolysis requires acidic media. 10,11 During the course of stabilization of metal alkoxides for the fabrication of metal oxides and because of the interest in how structural change would alter the final texture of the metal oxides, we have synthesized Ti(C 9 H 6 NO) 2 (OCH 2 CH 2 OR) 2 complexes, where R CH 3 (1) and R C 2 H 5 (2), and characterized them using various spectroscopic techniques, in addition to X-ray single-crystal structure determination of compound 1.…”