The first metallasilsesquioxanes comprising potassium and uranium have been synthesized and structurally characterized by single-crystal X-ray diffraction. (Cy7Si7O12)2K6(DME)4 (2; Cy = cyclohexyl) is a centrosymmetric dimer, in which the two silsesquioxide ligands are interconnected by μ3- and μ4-bridging siloxide moieties. (Cy7Si7O12)2UVI (3) represents the first metallasilsesquioxane complex of an actinide element, featuring a U atom that is coordinated by two tridentate silsesquioxide ligands in a distorted octahedral fashion. The different structural effects of the large metal atomic radii are discussed.

This research report summarizes recent results in the chemistry of lanthanide disiloxanediolates and metallasilsesquioxanes. Both classes of compounds can be regarded as realistic model compounds for silica-supported lanthanide catalysts.

Treatment of anhydrous YbCl3 with LiN(SiMe3)(2) followed by reaction with 1 equivalent of 1,1,3,3,5,5-hexaphenyl-1,3,5-trisiloxanediol afforded the First mono(trisiloxanediolate) complex of a rare earth element. The compound [Ph2Si(OSiPh2O)(2)]-Yb(THF)(mu-Cl)(3)Li-2(THF)(3) (1) was isolated in the form of colorless crystals in very high yield (93%). A single-crystal X-ray diffraction study confirmed the presence of an eight-membered inorganic ring system containing ytterbium. Coordination of one THF ligand and retention of two equivalents of lithium chloride lead to formation of all "ate" complex.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The reaction of samarium(II) diiodide with in situ prepared disodium-1,1,3,3-tetraphenyl-1,3-disiloxanediolate, [(Ph2SiONa)(2)O], afforded the unusual heterobimetallic samarium(III) disiloxanediolate cluster [Me3SiO{mu-Na(THF)}(3)-Sm{mu-(Ph2SiO)(2)O}(3)Na(THF)] (1) in low yield. A single-crystal X-ray structure determination of I revealed the presence of a poly-cylic inorganic ring system in which the samarium atom is not only chelated by three [(Ph2SiO)(2)O](2-) ligands but is also part of a SmNa3O4 heterocubane cage.

The previously proposed concept of "inorganic metallocenes" of group 3 and rare-earth elements has been tested by preparing a series of novel disiloxanediolates with metals displaying different ionic radii. For the smaller scandium and yttrium, approximately planar arrangements of the disiloxanediolate frameworks with solvent and chloride ligands in trans positions were found. Thus, the compounds [{(Ph2SiO)2O}2{Li(DME)}2]ScCl(THF/DME) (2; DME=1,2-dimethoxyethane and THF=tetrahydrofuran) and [{(Ph2SiO)2O}2{Li(THF)2}2]YCl(THF) (3) can be described as heterobimetallic inorganic ring systems or metallacrown complexes with "in-plane" coordination of the metal. In contrast, "out-of-plane" geometries with cis coordination of additional ligands were identified in the praseodymium derivatives [{(Ph2SiO)2O}2{Li(THF)2}{Li(THF)}]Pr(micro-Cl)2Li(THF)2 (4) and [{(Ph2SiO)2O}2{Li(DME)}2]PrCl(DME) (5). These compounds can be viewed as analogues of the known metallocene derivatives (C5Me5)2Pr(micro-Cl)2Li(THF)2 and (C5Me5)2PrCl(THF). The molecular structures of 2-5 have been determined by X-ray diffraction.

The first disiloxanediolate complexes of cerium(IV) are reported. Starting from the readily available precursor (tBuO)3CeIV(NO3)(THF)2 (1), we prepared the novel heterobimetallic compounds [{(Ph2SiO)2O}{K(THF)2}]2Ce(OtBu)2 (2) and [{(Ph2SiO)2O}2{(DME)-KOtBu}{(Ph2SiO2)K}Ce]2 (3) and structurally characterized them by X-ray diffraction.

Novel transformations of lanthanide(III) disiloxanediolates with group 13 metal trialkyls are reported. Treatment of the scandium metallacrown complex [{(Ph2SiO)2O}2{Li(DME)}2]ScCl.THF (1) with AlMe3 resulted in an Li-Al exchange reaction and the formation of the heterotrimetallic inorganic ring system [{(Ph2SiO)2O}2{Li(THF)2}AlMe2]ScCl.THF (2). The related yttrium metallacrown [{(Ph2SiO)2O}2{Li(THF)2}2]YCl.THF (3) reacts with InMe3 under the formation of the heterobimetallic Y/In disiloxanediolate complex [{(Ph2SiO)2O}2{InMe2(OMe)}2InMe2]Y (4). In the latter, two monomeric Me2InOMe ligands are stabilized through coordination to yttrium.

The reactivity of neodymium chiodide, NdI2 (1), towards organosilicon, -germanium and -tin halides has been investigated. Compound 1 readily reacts with Me3SiCl in DME to give trimethylsilane (6 %), hexamethyldisilane (4 %) and (Me3Si)(2)O (19%). The reaction with Et3SiBr in THF results in formation of Et3SiSiEt3 (17 %) and Et3SiOBun (34 %). Alkylation Of Me3SiCl with (PrCl)-Cl-n in the presence of 1 in THF affords Me3SiPrn (10 %), MC3SiOBun (52%) and Me3SiSiMe3 (1 %). The main product identified in the reaction mixture formed upon interaction of 1 with dichlorodimethylsilane Me2SiCl2 in THF is di-n-butoxydimethylsilane Me2Si(OBUn)(2) (54%) together with minor amounts of Me2Si(OBun)Cl. The reaction of 1 with Me3GeBr under the same conditions produces Me3GeGeMe3 (44 %), Me3GeH (3 %), and Me3GeI (7 %). An analogous set of products was obtained in the reaction with Et3GeBr. Treatment of trimethyltin chloride with I causes reduction of the former to tin metal (74 %). Me3SnH (7 %) and hexamethyldistannane (11 %) were identified in the volatile products. The reaction of 1 with Me3SiI provides straightforward access to hepta-coordinated NdI3(THF)(4) (2), the structure of which was determined by X-ray diffraction.

Angewandte Chemie International EditionVolume 43, Issue 35 p. 4603-4606 Communication Fully Metalated Silsesquioxanes: Building Blocks for the Construction of Catalyst Models† Volker Lorenz Dr., Volker Lorenz Dr. Chemisches Institut, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany, Fax: (+49) 391-671-2933Search for more papers by this authorStephan Gießmann Dr., Stephan Gießmann Dr. Chemisches Institut, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany, Fax: (+49) 391-671-2933Search for more papers by this authorYurii K. Gun'ko Dr., Yurii K. Gun'ko Dr. Department of Chemistry, Trinity College, Dublin 2, IrelandSearch for more papers by this authorAxel K. Fischer Dr., Axel K. Fischer Dr. Chemisches Institut, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany, Fax: (+49) 391-671-2933Search for more papers by this authorJohn W. Gilje Prof. Dr., John W. Gilje Prof. Dr. Chemistry Department, James Madison University, Harrisonburg, VA 22807, USASearch for more papers by this authorFrank T. Edelmann Prof., Frank T. Edelmann Prof. [email protected] Chemisches Institut, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany, Fax: (+49) 391-671-2933Search for more papers by this author Volker Lorenz Dr., Volker Lorenz Dr. Chemisches Institut, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany, Fax: (+49) 391-671-2933Search for more papers by this authorStephan Gießmann Dr., Stephan Gießmann Dr. Chemisches Institut, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany, Fax: (+49) 391-671-2933Search for more papers by this authorYurii K. Gun'ko Dr., Yurii K. Gun'ko Dr. Department of Chemistry, Trinity College, Dublin 2, IrelandSearch for more papers by this authorAxel K. Fischer Dr., Axel K. Fischer Dr. Chemisches Institut, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany, Fax: (+49) 391-671-2933Search for more papers by this authorJohn W. Gilje Prof. Dr., John W. Gilje Prof. Dr. Chemistry Department, James Madison University, Harrisonburg, VA 22807, USASearch for more papers by this authorFrank T. Edelmann Prof., Frank T. Edelmann Prof. [email protected] Chemisches Institut, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany, Fax: (+49) 391-671-2933Search for more papers by this author First published: 01 September 2004 https://doi.org/10.1002/anie.200454094Citations: 42 † This work was supported by the Deutsche Forschungsgemeinschaft (Schwerpunktprogramm "Spezifische Phänomene der Silicium-Chemie"), the Fonds der Chemischen Industrie, and the European Commission (contract G1RD-CT-1999-00167 "SAFEGAS"). Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Graphical Abstract Versatile building blocks for the construction of molecular models for heterogeneous catalysts are readily available in high yields in the form of fully metalated silsesquioxane derivatives, such as dimeric 1, by using alkali-metal silylamides as deprotonating agents. Citing Literature Volume43, Issue35September 6, 2004Pages 4603-4606 RelatedInformation

Novel silyl-functionalized silsesquioxane building blocks have been prepared by treatment Of Cy7Si7O9(OH)(3) (1, Cy = c-C6H11) with hexachlorodisilane or hexachlorodisiloxane, respectively, in the presence of triethylamine. Reactions in a 1:1 molar ratio afforded the trichlorosilyl-functionalized silsesquioxane derivatives Cy7Si8O12SiCl3 (2) and Cy7Si8O12OSiCl3 (3). Related bis(silsesquioxanes), (Cy7Si8O12)(2) (4) and (Cy7Si8O12)(2)O (5) are accessible in a similar manner by employing a 2:1 molar ratio of the reactands. Compound 1 also served as a starting material in the preparation of the partially closed silsesquioxane cages Cy7Si7O11(OH)SiMe2 (6) and Cy7Si7O11(OH)Si(OEt)(2) (7), while the related condensation product Cy7Si7O10(OSiMe3) (9) was made by AlCl3-catalyzed elimination of water from Cy7Si7O9(OH)(2)-OSiMe3 (8). The molecular structure of 9 was determined by Xray diffraction.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Treatment of Cy7Si7O9(OH)3 (1) with Me2SiCl2 (molar ratio 2:3) in the presence of triethylamine affords the Me2Si-bridged bis(silsesquioxane) derivative Me2Si[Cy7Si7O10(O2SiMe2)]2 (5). The novel silsesquioxane vinyl monomer Cy7Si7O9(OSiMe2CHCH2)3 (7) has been synthesized by reacting in situ generated Cy7Si7O9(OLi)3 (6) with three equivalents of Me2SiCl(CHCH2). The molecular structures of 5 and 7 as well as that of the known silyl-functionalized silsesquioxane precursor Cy7Si7O9(OH)(OSiMe3)2 (3) have been determined by X-ray diffraction.

Two modern areas of metallasiloxane chemistry are reviewed. The first part deals with the preparation and structural characterization of the first f-element compounds derived from tetraphenylsisiloxanediol. In the second part recent developments in the chemistry of polyhedral metallasilsesquioxanes are surveyed, with special emphasis being placed on early transition metal and f-element derivatives. Also highlighted are applications of these species in catalysis research.

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The first copper(I) silsesquioxane derivative, Cu4O4[Cy7Si7O9(OSiMe3)]2 (4) was prepared by reacting tetrameric copper(I)-t-butoxide, (CuOtBu)4 (3), with the monosilylated silsesquioxane precursor Cy7Si7O9(OH)2(OSiMe3) (2) in a 1:2 molar ratio. An X-ray diffraction study revealed the presence of a centrosymmetric dimer. A slightly puckered Cu4O4 ring forms the central part of a complex structure comprising nine eight-membered inorganic ring systems.

Constituting a novel synthetic route to model compounds for titanium catalysts immobilized on silica, the disilylated silsesquioxane derivative Cy7Si7O9(OH)(OSiMe3)(2) 2a, has been reacted with the 'tucked-in' fulvene complex Cp*Ti(C5Me4CH2) to give the titanium(III) silsesquioxane Cp*Ti-2[Cy7Si7O10(OSiMe3)(2)] 3, while treatment of Cp*Ti(C5Me4CH2) with Cy7Si7O9(OH)(2)(OSiMe3) 2b affords the mono(pentamethylcyclopentadienyl) complex Cp*Ti[Cy-7-Si7O11(OSiMe3)][Cy7Si7O10(OH)(OSiMe3)] 4 which is an advanced model compound for a catalytically active titanium center on a silica surface.

The triethylamine-assisted metathesis reaction of 2 equiv of Cy7Si7O9(OSiMe3)(OH)(2) with 1 equiv of AlCl3 affords the novel anionic aluminosilsesquioxane complex [HNEt3][{Cy7Si7O9(OSiMe3)O-2}(2)Al]. C6H14 (Cy = c-C6H11), 1, which was characterized by IR and H-1, C-13, and Si-29 NMR spectroscopy and X-ray diffraction.