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  • 11
    Electronic Resource
    Electronic Resource
    Homo- und Hetero-Metall-Amide des Tris(tert-butylamino)methylsilans - Polycyclen und Cluster mit Li, Na, Mg, Al und Tl (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2625-2635 
    Details
    ISSN: 0009-2940
    Keywords: Amides, hetero metal ; Polycycles ; Metal clusters of thallium ; Metal nitrogen bonding ; Carbanion, stabilized by metal complexation ; Silane, tris(tert-butylamino) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Homo and Hetero Metal Amides of Tris(tert-butylamino)methylsilane - Polycycles and Clusters with Li, Na, Mg, Al and TlThe hydrogen atoms attached to nitrogen in tris(tert-butyl-amino)methylsilane (1) can be substituted by metallic main-group elements in a quite general way. If 1 is treated with trimethylaluminium apart from the monosubstituted product MeSi(tBuNH)2(tBuNAlMe2) (2) the trisamide MeSi(tBuNAlMe2)3 (3) is obtained. In similar ways complete substitution of the amino hydrogen atoms in 1 yields the compounds MeSi[tBuNMgN(SiMe3)2]3 (6), [MeSi(tBuNLi)3]2 (10), and [MeSi(tBuNTl)3]2 (11), the later two being dimeric. If methyl-magnesium iodide is allowed to react with 1 the intermediate MeSi(tBuNMgI)3 (4) in some instances can be isolated as the THF adduct or may react with a further equivalent of the Grignard compound to generate the complex [MgI-(THF)5]+ [MeSi(tBuNMgI)3CH3 · THF]- (5). The aluminium compound 2 has been used to access to heterometallic amides combining aluminium and sodium as in MeSi(tBuNAlMe2)(tBuNNa)(tBuNH) (7) or magnesium and aluminium as in the dimeric compounds [MeSi(tBuNAlMe2)(tBuNH)(tBuNMgI)]2 (8) and [MeSi(tBuNAlMe2)(tBuNH)(tBuNMgMe)]2 (9). X-ray structure analyses reveal 3 (tricyclic SiN3Al3 skeleton with Al - N distances from 2.014 to 2.025 Å), 6 (tricyclic Si-N3Mg3 skeleton), and 7 [bicyclic SiN3AlNa skeleton with Na - N distances of 2.47(1) and 2.52(1) Å] to be monomeric even in the solid state. The compounds 8 and 9 (both pentacyclic with spiro magnesium atoms) form centrosymmetric dimers by Mg - I - Mg and Mg - (CH3) - Mg bridges, respectively. The dimers 10 and 11 are completely different in terms of chemical bonding: while in the lithium compound 10 a centrosymmetric polycycle is formed by principly ionic interactions of the lithium atoms with corresponding nitrogen atoms, the centrosymmetric dimer in 11 is held together by Tl - Tl bonds. The X-ray structure analysis of 5 reveals the anion containing a Mg-coordinated CH3-.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261210
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  • 12
    Electronic Resource
    Electronic Resource
    Cyclische Diazastannylene, XXIV. Zur Umsetzung von (tert-Butylimino)stannylen mit Chlorwasserstoff (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 347-355 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclic Diazastannylenes, XXIV. - The Reaction of (tert-Butylimino)stannylene with Hydrogen Chloride(tert-Butylimino)stannylene (1) reacts with hydrogen chloride to form [tBuN(H)-SnCl]2 (2a), tBuNH2 · SnCl2 (3), and tBuNH3⊕ SnCl3⊖ (4). As separation of the crystalline products is difficult, alternative syntheses for 2a, 3 and 4 are necessary. Me2Si[N(tBu)H][N(tBu)]SnX (6a: X = Cl, 6b: X = Br, 6c: X = I) is a substrate which may be treated with tert-butylamine to yield 2a (X = Cl) or 2b (X = Br) quantitatively. 3 and 4 are obtained from 2a by addition of HCl. 6a, b, and c show temperature dependance in the 1H-NMR spectra which is due to intramolecular ligand rearrangements. X-ray determinations reveal 6a to crystallize in an orthorhombic lattice (space group P212121), 3 in two different lattices (monoclinic, P21/c, and triclinic, P1), and 4 again in a triclinic lattice P1). 6a is a molecule with an intramolecular donor-acceptor bond [Sn-N = 2.347(6) Å], 3 adopts the same structure in the two modifications consistent with an adduct of SnCl2 and tBuNH2 [Sn-N = 2.334(4) Å (monoclinic) and 2.338(4) Å (triclinic)], and and 4 has to be formulated as an ion pair tBuNH3⊕ SnCl3⊖ connected by H-Cl bridges in the crystal [Sn-Cl = 2.542 (mean number), C-N = 1.515(6) Å].
    Notes: (tert-Butylimino)stannylen (1) reagiert mit Chlorwasserstoff zu [tBuN(H)-SnCl]2 (2a), tBuNH2 · SnCl2 (3) und tBuNH3⊕ SnCl3⊖ (4). Da die Trennung der kristallinen Produkte Schwierigkeiten macht, ist man auf Alternativsynthesen von 2a, 3 und 4 angewiesen. Me2Si[N(tBu)H][N(tBu)]SnX (6a: X = Cl, 6b: X = Br, 6c: X = I) stellt eine Ausgangsstufe dar, die mit tert-Butylamin zu 2a (X = Cl) und 2b (X = Br) quantitativ umgesetzt werden kann. 3 und 4 entstehen aus 2a u.a. durch HCl-Addition. 6a, b und c zeigen unterschiedliche 1H-NMR-Spektren in Abhängigkeit von der Temperatur, was auf eine intramolekulare Ligandenumordnung hinweist. Die Röntgenstrukturanalysen von 6a (orthorhombisch, Raumgruppe P112121), 3 (monoklin, P21/c, und triklin, P1) und 4 (triklin, P1) weisen 6a als Molekül mit einer intramolekularen Donor-Akzeptor-Bindung [Sn-N = 2.347(6) Å], 3 in beiden Modifikationen als Addukt von SnCl2 an tBuNH2 [Sn-N = 2.334(4) Å (monoklin) bzw. 2.338(4) Å (triklin)] und 4 als Ionenpaar tBuNH3⊕ SnCl3- mit H-Cl-Brücken im Kristall aus [Sn-Cl = 2.542 (Mittelwert), C-N = 1.515(6) Å].
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210222
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  • 13
    Electronic Resource
    Electronic Resource
    Zur Reaktion polycyclischer Alkoxysilylamide von Li, Na und K mit organischen Lewis-Basen (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 841-849 
    Details
    ISSN: 0009-2940
    Keywords: Lewis acid-base adducts ; Alkali metal amides ; Chelated metals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Reaction of Polycyclic Alkoxysilylamides of Li, Na, and K with Organic Lewis BasesIndependently of the ligand at the nitrogen atom (tert-butyl or trimethylsilyl) the polycyclic and dimeric lithium (alkoxysilyl)-tert-butylamide 1 or lithium (alkoxysilyl)silylamide 2 react with bases like pyridine, tetrahydrofuran, or dioxane to form the acidbase adducts 1a, 1b, 1c, and 2a of similar structure. An X-ray structure analysis of 1b confirms the base tetrahydrofuran being coordinated by the oxygen to one of the lithium atoms while the other is surrounded by oxygen and nitrogen atoms of the siloxyamide ligand. The two metal atoms have different coordination numbers (3 versus 4), the shorter distances are found at the one [Li(2)] with less neighbours. Even an excess of the base does not lead to complexes in which the two metal atoms within the molecule have equal degree of saturation or have an equal environment. Nevertheless this situation can be reached with the corresponding sodium compound 3, which forms 3a by contact with pyridine. In this product the two sodium atoms have an identical coordination sphere being bound to three nitrogen and one oxygen atom. A compound with different sodium atoms is formed when 3 is treated with α,α′-bipyridine. This astonishing unsymmetry in the coordination of the two metal atoms is not realized in the corresponding potassium compound 4a, formed from 4 and α,α′-bipyridine (equally coordinated potassium atoms). The existence of acid-base adducts of 3 and 4 with phenanthroline and different crown ethers has been proven.
    Notes: Unabhängig vom Liganden am Stickstoffatom (tert-Butyl oder Trimethylsilyl) reagiert das polycyclische und dimere Lithium-(alkoxysilyl)-tert-butylamid 1 bzw. Lithium-(alkoxysilyl)silylamid 2 mit den Basen Pyridin, Tetrahydrofuran bzw. Dioxan zu Säure-Base-Addukten 1a, 1b, 1c und 2a mit ähnlicher Struktur Nach der Röntgenstrukturanalyse von 1b koordiniert die Base Tetrahydrofuran über den Sauerstoff an eines der beiden Lithiumatome, während das andere von den Sauerstoff- und Stickstoff-atomen des Siloxyamidliganden umgeben ist. Die beiden Metallatome besitzen unterschiedliche Koordinationszahlen (3 und 4), wobei Li(2) aufgrund der geringeren Anzahl der Nachbarn die kürzesten Abstände bildet. Selbst ein Basenüberschuß führt nicht zur Bildung von Komplexen, bei denen die beiden Metallatome im Molekül gleichen Sättigungsgrad und gleiche Umgebung erreichen. Möglich ist dies jedoch bei der entsprechenden Natriumverbindung 3, die mit Pyridin zu der Verbindung 3a reagiert. In diesem Produkt besitzen beide Natriumatome dieselbe Koordinationssphäre mit je drei Stickstoff- und einem Sauerstoffatom als Nachbarn. Setzt man 3 mit α,α′-Bipyridyl um, so entsteht eine Verbindung mit Natriumatomen unterschiedlicher Umgebung. Diese erstaunliche Unsymmetrie in der Koordination der beiden Metallatome liegt bei der entsprechenden Kaliumverbindung 4a, gewonnen aus 4 und α,α′-Bipyridyl, nicht vor (gleichartig koordinierte Kaliumatome). Säure-Base-Addukte von 3 und 4 mit Phenanthrolin und Kronenethern waren nachzuweisen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220508
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  • 14
    Electronic Resource
    Electronic Resource
    Alkoxygermanate(II), -stannate(II) und -plumbate(II) zweiwertiger Metall-Ionen, II. Verbindungen des Formeltyps M2El2(OtBu)8 (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1033-1042 
    Details
    ISSN: 0009-2940
    Keywords: Germanium compounds ; Tin compounds ; Lead compounds ; Transition-metal complexes ; Paramagnetism ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkoxygermanates(II), -stannates(II), and -plumbates(II) of Divalent Metal Ions, II[1]. - Compounds of the Formula M2El2(OtBu)8By simple salt-exchange processes the starting materials Na2El2(OtBu)6 (El = Ge, Sn, Pb) can be transformed to germanates, stannates and plumbates of divalent magnesium and divalent transition metals. Two types of compounds are formed in these reactions: MEl2(OtBu)6 [El = Ge, M = Mg (1A), Cr (1B), Mn (1C), Zn (1F); El = Pb, M = Mn (3C), M = Zn (3F)] and M2El2(OtBu)8 [El = Ge, M = Co (1d), Ni (1e); El = Sn, M = Mg (2a), Cr (2b), Mn (2c), Co (2d), Ni (2e); El = Pb, M = Co (3d)]. Single-crystal X-ray diffraction studies have been performed on 1C, 1d, 2a, 2b, 2c, 2d, and 2e, and the structures have been solved. In 1C the Mn atom occupies the center of an elongated O6 octahedron, the germanium(II) atoms displaying pyramidal coordination by three oxygen atoms. The central molecular cage can be described as two MnO3Ge trigonal bipyramids sharing the common central Mn atom and being wrapped by tert-butyl groups linked to the oxygen atoms. The other compounds of the MEl2(OtBu)6 formula seem to be isostructural with the exception of 3F, which displays a 1H-NMR spectrum which is not compatible with this structure. All X-ray structures of the compounds M2El2(OtBu)8 show the same feature: to a central M2(OtBu)2 four-membered ring are spirocyclically connected two M(OtBu)2El rings through the common metal atoms M. The structure is completed by the coordination of an exocyclic tert-butoxy group to the terminal El atoms. The metal atoms M are therefore quasi tetrahedrally coordinated while the Ge and Sn atoms are in pyramidal threefold oxygen atom environments. All molecules display an El⃛M⃛M⃛El one-dimensional arrangement. From susceptibility measurements it is apparent, that in the compounds MEl2(OtBu)6 and M2El2(OtBu)8 the transition metal atoms are in high-spin configurations, which is also supported by the UV spectra. Analysis of the structural data of the series 2a-2e reveal important contributions of the electronic environments of the transition metal atoms to the M⃛M and M⃛Sn distances. A qualitative MO description is used to explain these features. Again it has been shown that the, „geometrical softness“ of Ge(OtBu)3 and Pb(OtBu)3 is greater than of Sn(OtBu)3, as the former two can accomodate Cr2+ and Mn2+ in a sixfold coordination site by two units, while Sn(OtBu)3 coordinates Cr2+ and Mn2+ with only two alkoxy groups. When 1C and 2d are allowed to react with nonacarbonyldiiron Mn-Ge2(OtBu)6 · 2 Fe(CO)4 (4) and Co2Sn2(OtBu)8 · 2 Fe(CO)4 (5), respectively, are formed. Compound 4 displays presumably five metal atoms in a linear arrangement while 5 has six metallic elements arranged in one dimension. The latter fact has been unambigously proved by an X-ray structure determination.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250509
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  • 15
    Electronic Resource
    Electronic Resource
    (tert-Butoxy)aluminium and -gallium HydridesDedicated to Prof. H. W. Roesky on the occasion of his 60th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 381-384 
    Details
    ISSN: 0009-2940
    Keywords: Alanes, tert-butoxy- and bis(tert-butoxy)- ; Gallanes, tert-butoxy- and bis(tert-butoxy)- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structures obtained by X-ray methods of (tert- butoxy)alane and -gallane (tBuOMH2) are isotypic and are composed of discrete centrosymmetric dimers. The dimers arise from almost symmetrical Al—O—Al [1.810(3), 1.815(3) Å] and Ga—O—Ga [1.902(9), 1.908(9) Å] bridges forming a central rhombohedral four membered M2O2 cycle [O—Al—O 81.0(2)°, O—Ga—O 78.6(5)°] with the metallic atoms in a distorted tetrahedral environment. When one of the hydride ligands on the metals is further substituted by tert-butoxy, the formation of (tBuO)2AlH and (tBuO)2 GaH is observed. These two compounds crystallize in different lattices and space groups, but they are nevertheless very similar in their structure: the centrosymmetric M2O2 cycle is maintained [Al—O 1.817(3), 1.817(3) Å; Ga—O 1.904(4), 1.907(4) Å] As expected, the terminal Al-O [1.675(3) Å] and Ga—O [1.783(4) Å] distances are considerably shorter than the bridging ones.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290403
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  • 16
    Electronic Resource
    Electronic Resource
    Polycyclische Silylamide mit λ3-Li und λ3-Tl (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 943-949 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polycyclic Silylamides with λ3-Li and λ3Tl1,3-Di-tert-butyl-2,4-bis(tert-butylamino)-2,4-dimethyl-1,3,2,4-diazadisiletidine can be obtained in two different stereochemical forms: in the cis compound 3a the methyl or tert-butylamino substituents on the silicon are on one side of the central Si2N2 four-membered ring, while in the trans compound 3b they are on opposite sides. The hydrogen atoms at the nitrogen atoms can be replaced by univalent lithium or thallium(I) atoms. Starting from the cis compound 3a, a molecular polycycle is obtained. As confirmed by X-ray structure determinations, the Si2N4M2 skeleton is cubane-like. In the lithium derivative 5a and the thallium compound 6 both of the metal atoms within the cage are pyramidally coordinated by three nitrogen atoms. In contrast to the thallium atoms which have a rare gas electron environment, the λ3-lithium atoms are electronically and coordinatively unsaturated. In the solid this fact enduces “dimerization” of the molecules 5a resulting in C—H…Li “contacts” to each lithium. The trans isomer 3b reacts with butyllithium to form a tricyclic compound 5b, in which the lithium atoms are further coordinated by one ether molecule. A coordination number of 3 is therefore found at the lithium atoms: contrary to the cis isomer 5a the figure around lithium is trigonal planar. The Li—N(2) distance within 5b is remarkably short [188(3) pm], which probably results from the sp2-hybridization at the metal.
    Notes: 1,3-Di-tert-butyl-2,4-bis(tert-butylamino)-2,4-dimethyl-1,3,2,4-diazadisiletidin kann in zwei stereochemisch unterschiedlichen Formen erhalten werden: in der cis-Verbindung 3a stehen die Methyl- bzw. tert-Butylaminosubstituenten am Silicium auf derselben Seite des zentralen Si2N2-Vierringes, während sie in der trans-Verbindung 3b entgegengesetzte Positionen einnehmen. Die Wasserstoffatome an den Stickstoffatomen lassen sich durch einwertige Metalle wie Lithium oder Thallium(I) ersetzen. Geht man dabei von der cis-Verbindung 3a aus, so entsteht ein molekularer Polycyclus mit einem cubanartigen Si2N4M2-Gerüst, was durch Röntgenstrukturanalysen nachgewiesen werden kann. Sowohl im Lithiumderivat 5a als auch in der Thallium-Verbindung 6 sind die beiden im Polycyclus befindlichen Metallatome jeweils von 3 Stickstoffatomen pyramidal koordiniert. Während für das Thalliumatom eine formale Edelgaskonfiguration entsteht, sind die λ3-Li-Atome elektronisch und koordinativ ungesättigt: im Festkörper wirkt sich diese Tatsache in einer „Dimerisierung“ der Moleküle 5a aus, wobei C—H…Li-„Kontakte“ zustande kommen. Das trans-konfigurierte Isomer 3b reagiert mit Butyllithium zu einem tricyclischen System 5b, in dem die Lithiumatome durch ein zusätzliches Ethermolekül koordiniert werden. Die Koordinationszahl an den Lithiumatomen ist ebenso 3, aber die Figur ist trigonal planar. Besonders auffallend ist der kurze Li—N(2)-Abstand mit 188(3) pm, was mit der sp2-Hybridisierung am Metallatom zu erklären ist.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210520
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  • 17
    Electronic Resource
    Electronic Resource
    Complexes of Early Transition Metal Alkoxides: Molecular Structure of Ti(OiPr)4[OPb4(tBuN)3] (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1361-1363 
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    ISSN: 0009-2940
    Keywords: Titanium ; Lead ; Alkoxides ; Amides ; Mixed-Metal species ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction between Ti(OiPr)4 and [Pb(NtBu)2] (1) in refluxing THF afforded the complex Ti(OiPr)4OPb4(NtBu)3] (2) which has been characterized by X-ray diffraction studies and by 1H- and 13C-NMR spectroscopy. Titanium is five coordinate and it displays a trigonal bipyramidal stereochemistry with the pb4(tBuN)3O cage ligand bonded to titanium through the oxygen atom and occupying an apical position. The origin of the cubane lead ligand is discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300930
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  • 18
    Electronic Resource
    Electronic Resource
    Additionsreaktionen an intramolekular basenstabilisierte Ge=N- und Ge=S-Doppelbindungen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1135-1141 
    Details
    ISSN: 0009-2940
    Keywords: Germanium compounds with Ge double bonds, addition reactions of ; Germasilazanes, bicyclic ; Germazanes, isomeric ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition Reactions of Intramolecularly Base-Stabilized Ge=N and Ge=S Double Bonds.The Ge=N bond of 1 adds hydrogen chloride, ethanol, tert-butyl alcohol, methyllithium, and methyl iodide to form 3-6 and 8. The Ge=S bond in 2 analogously adds methyl iodide to yield 10. In the resulting products the electropositive part of the polar reactand is bound to nitrogen or sulfur, while the electronegative one is on the germanium atom. In the lithium derivative 6 and in the iodine derivative 8 Li and I can be replaced by hydrogen to form two isomers of the same composition 7 and 9, which differ only in the positions of the hydrogen and methyl groups with respect to Ge or N. The X-ray structure analyses on 4, 9, and 10 reveal that the germanium atom is fourfold coordinated by two nitrogen atoms and two other ligands. The intramolecular nitrogen base of the silazyl moiety in 1 and 2 is, thus, expelled from the coordination sphere of germanium by insertion of the double bonds into polar σ bonds, and the tricyclic molecule is changed to a bicyclic one. Thus these “base stabilized π bonds” in 1 and 2 behave as normal unsaturated systems.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240524
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  • 19
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    Electronic Resource
    Tuning Metal Stoichiometry in Heterometal Alkoxides: First Structurally Characterised Molecular Precursor to BaZrO3 (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1327-1332 
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    ISSN: 1434-1948
    Keywords: Barium ; Zirconium ; O ligand ; Heterometal alkoxides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Manipulable metal ratios are accessible in a series of heterometal Ba-Zr alkoxides by changing the size and the charge of the ligands. The synthesis and characterisation of four mixed-metal Ba-Zr species [BaZr2(OtBu)10] (1), [Ba2Zr(OtBu)8(tBuOH)(THF)2] (2), [BaZr(OtBu)6(THF)2] (3) and [BaZr(OH)(OiPr)5(iPrOH)3]2 (4), based on different Ba/Zr stoichiometries, are reported. The molecular structures of 1, 2, and 4 have been determined by single-crystal X-ray diffraction studies. 1 exhibits a bow-tie structural motif in which a trigonally distorted six-coordinate barium atom is chelated by two bipyramidal {Zr(OtBu)5}- units. 2 reveals a triangular “Ba2Zr(μ3-OtBu)2(μ2-OtBu)3” core structure formed by the fusion of three octahedra built about two Ba atoms and a Zr atom. The structure is unique in terms of the distribution of terminal ligands at each of the metal centers. One of the barium atoms possesses one -OtBu and one tBuOH as terminal ligands, while the terminal ligands on the second barium atom are two THF molecules; the zirconium center bears -OtBu groups as the terminal ligands. Hydrolysis of compound 3 with one equivalent of water, followed by alcoholysis (iPrOH) of the resulting product, gave 4. The structure of 4 shows a planar tetrametallic Ba2Zr2 frame capped by two μ3-hydroxo ligands. The coordination figure of the zirconium atoms resembles a distorted octahedron, whereas the geometry of the barium centers is best described as capped trigonal prisms. Both 3 and 4 are excellent precursors to morphologically pure BaZrO3 ceramic by the sol-gel process.
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  • 20
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    Electronic Resource
    Synthesis and Single-Crystal X-ray Diffraction Studies on New Methylindium(III) Alkoxides (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1343-1350 
    Details
    ISSN: 1434-1948
    Keywords: Indium ; O ligands ; N ligands ; C ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New heteroleptic indium compounds have been synthesized starting from indium(III) halides and hexamethyldisilazyllithium to form MeXInN(SiMe3)2 [X = Cl (1), Br (2)], and then subsequent alcoholysis to afford the molecules [ClMeIn(OtBu)]2 (3), [BrMeIn(OtBu)]2 (4), {ClMeIn[O(C6H4)OMe]}2 (5), {[(SiMe3)2N]MeIn(OtBu)}2 (6) and [MeIn(OtBu)2]2 (7). The molecular structures of molecules 3-7 have been obtained by single crystal X-ray diffraction studies. The structures of the compounds 3-7 are almost identical: 3-5 crystallize in the monoclinic crystal system with two dimeric molecules per unit cell in the space group P21/c, 6 crystallizes in the monoclinic space group C2/c with four molecules per unit cell, and compound 7 crystallizes in the triclinic crystal system with one dimeric molecule per unit cell in the space group P-1. The central centrosymmetric In2O2 ring, common to all the compounds, is achieved by two bridging oxygen atoms. Due to the additional coordination by an oxygen atom of the methoxy group, the coordination number of the metal center rises from 4 to “4+1” if the OtBu ligand (compounds 3, 4, 6, and 7) is exchanged for a methoxyphenol ligand (compound 5). In addition to the In2O2 ring the compound 5 possesses two annealed five-membered InO2C2 rings. The common indium methyl group of all compounds, which is transfered by an original route from the silicon to the indium atom, is used to compare structural and spectroscopic properties of the molecules, as there is a correlation between the In-C bond length and the chemical shift of the methyl group which depends on the ligand system used.
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