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首页> 外文期刊>Polyhedron: The International Journal for Inorganic and Organometallic Chemistry >Preparation of volatile molecular lithium-niobium allioxides. Crystal structures of [Nb(mu-OCH2SiMe3)(OCH2SiMe3)(4)](2) and [LiNb(mu(3)-OCH2SiMe3)-(mu(2)-OCH2SiMe3)(2)(OCH2SiMe3)(3)](2)
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Preparation of volatile molecular lithium-niobium allioxides. Crystal structures of [Nb(mu-OCH2SiMe3)(OCH2SiMe3)(4)](2) and [LiNb(mu(3)-OCH2SiMe3)-(mu(2)-OCH2SiMe3)(2)(OCH2SiMe3)(3)](2)

机译:制备挥发性分子锂铌铝氧化物。 [Nb(mu-OCH2SiMe3)(OCH2SiMe3)(4)](2)和[LiNb(mu(3)-OCH2SiMe3)-(mu(2)-OCH2SiMe3)(2)(OCH2SiMe3)(3)的晶体结构(2)

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摘要

New heterometallic alkoxides [LiNb(OCH2CMe3)(6)](2) (4), LiNb(OCH2CMe3)(6)(Me3CCH2OH)(2) (5), and [LiNb(OCH2SiMe3)(6)](2), (6) have been prepared from the corresponding homometallic alkoxides. All are moderately soluble in hydrocarbons and sublime in moderate to good recoveries. The structure of 6 determined crystallographically contains an Nb2Li2(mu-O)(4)(mu(3)-O)(2) central-core geometry. Compound 4 appears to be isostructural on the basis of H-1 NMR data. Bulk pyrolysis of 4 gives crystalline LiNbO3 under N-2 at 600 degrees C. However, LiNbO3 films are not obtained from 4 by spray MOCVD under conditions that give LiNbO3 films from [LiNb(OEt)(6)](infinity). Crystallographic structure determination for the precursor compound [Nb(mu-OCH2SiMe3) (OCH2SiMe3)(4)](2) (3) reveals an edge-shared bioctahedral geometry in which the mu-O atoms are distinctly pyramidal. This structure is maintained in solution; the pyramidal bridge configurations allow coexistence of syn and anti dimeric isomers. Precursor 3 also exhibits a dimer-monomer equilibrium for which Delta H = 63(3) kJ/mol and Delta S = 180(10) J/(K mol). (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 25]
机译:新的杂金属醇盐[LiNb(OCH2CMe3)(6)](2)(4),LiNb(OCH2CMe3)(6)(Me3CCH2OH)(2)(5)和[LiNb(OCH2SiMe3)(6)](2), (6)已经由相应的均金属醇盐制备。所有化合物均适度溶于烃类,并以中等至良好的采收率升华。在晶体学上确定的6的结构包含Nb2Li2(mu-O)(4)(mu(3)-O)(2)中心核几何形状。基于H-1 NMR数据,化合物4似乎是同构的。 4的本体热解在600°C的N-2下产生结晶的LiNbO3。但是,在[LiNb(OEt)(6)]无限大的条件下,通过喷雾MOCVD不能从4获得LiNbO3膜。前体化合物[Nb(mu-OCH2SiMe3)(OCH2SiMe3)(4)](2)(3)的晶体结构确定揭示了其中mu-O原子明显呈金字塔形的边共享生物体面几何。此结构保持在解决方案中;锥体桥构型允许顺式和反式二聚体异构体共存。前体3还表现出二聚体单体平衡,对于该平衡体,ΔH= 63(3)kJ / mol和ΔS= 180(10)J /(Kmol)。 (C)1998 Elsevier ScienceLtd。保留所有权利。 [参考:25]

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