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  • 1
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    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.
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    URL: http://dx.doi.org/10.1002/cber.19921250509
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  • 2
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    Strukturell unterschiedliche Metallamide (Li, Cu, Ag, Cd) mit dem Chelatliganden [tBu-N-SiMe2-O-C6H4-O-Sime2-N-tBu]2-Herrn Professor Heinrich Nöth zum 65. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2383-2388 
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    ISSN: 0009-2940
    Keywords: Silazane, phenoxy- ; Metal amides (Li, Cu, Ag, Cd) ; Metal-metal interactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structurally Different Metal Amides (Li, Cu, Ag, Cd) with the Chelating Ligand [tBu-N-SiMe2-O-C6H4-O-SiMe2-N-tBu]2-Herrn Professor Heinrich Nöth zum 65. Geburtstag gewidmet.The amino hydrogen atoms in the silylamine o-C6H4O2(Me2SiN(H)tBu)2 (1) can be replaced by monovalent (Li, Cu, Ag) or divalent (Cd) metallic elements. Whereas the lithium compound is obtained as an ether adduct, [C6H4O2(Me2SiNtBu)2]Li2 · OEt2 (2), the copper and silver compounds are solvens-free. The latter two form similar dimers comprising four metal atoms: [C6H4O2(Me2SiNtBu)2]2Cu4 (3) and [C6H4O2 (Me2SiNtBu)2]2Ag4 (4). The cadmium compound is also a dimer with two ligands and two cadmium atoms making up the molecule, [C6H4O2(Me2SiNtBu)2]2Cd2 (5). X-ray structure analyses reveal that in all compounds the metallic elements are highly coordinated by N and O interactions, with coordination numbers of 4 (2, 3, 4) and 5 (5). The oxygen contacts are quite long ranging from 260 to 301 pm. In the Cu und Ag compounds quadratic planar arrangements at the metals are found (bridged by nitrogen) with distances Cu-Cu 262.6(2)-270.1(2) and Ag-Ag 291.7(1)-301.8(2) pm.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261106
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  • 3
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    Cyclische Diazastannylene, VI. Darstellung und Charakterisierung des tetrameren tert-Butyl-iminostannylens und verwandter Käfige (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 2581-2587 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclic Diazastannylenes, VI. Preparation and Properties of Tetrameric tert-Butyliminostannylene and Related Cages1,3-Di-tert-butyl-2,2-dimethyl-1,3,2,4λ2-diazasilastannetidine (1) undergoes quantitative cleavage with tert-butylamine at 50°C in benzoic solution. According to the molar ratios of tert-butylamine and 1 the aminolysis products are the tricyclic cage Me2Si(NCMe3)2Sn2(NCMe3) (4) or the seco-norcubane-like molecule Sn3(NCMe3)4H2 (5) plus N,N′-di-tert-butyl-Si,Si-dimethylsilazane (3). 5 can be converted to the complete “cubane” Sn4(NCMe3)4 (6) quite easily. The structures of the compounds can be determined from high resolution 1H NMR and mass spectral data.
    Notes: 1,3-Di-tert-butyl-2,2-dimethyl-1,3,2,4λ2-diazasilastannetidin (1) wird bei 50°C in Benzol quantitativ durch tert-Butylamin gespalten. Als Aminolyseprodukte entstehen je nach Molverhältnis von tert-Butylamin zu 1 neben N,N-Di-tert-butyl-Si,Si-dimethylsilazan (3) ein tricyclischer Käfig Me2Si(NCMe3)2Sn2(NCMe3) (4) oder ein seco-norcubanartiges Molekül Sn3 (NCMe3)4H2 (5). Letzteres läßt sich leicht in das volle “Cuban” Sn4(NCMe3)4 (6) umwandeln. Die Konstitutionen der Verbindungen können aus hochaufgelösten 1H-NMR- und Massenspektren bestimmt werden.
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    URL: http://dx.doi.org/10.1002/cber.19791120726
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  • 4
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    Polycyclische Silylamide mit λ3-Li und λ3-Tl (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 943-949 
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    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.
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    URL: http://dx.doi.org/10.1002/cber.19881210520
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  • 5
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    Alkalimetallderivate eines Alkoxysilazans (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 603-607 
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    ISSN: 0009-2940
    Keywords: Molecules with chelated metals ; Unusual coordination numbers ; Polycyclic compounds with alkali metals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkali Metal Derivatives of an AlkoxysilazaneThe hydrogen atom of 1-tert-butoxy-1,1,3,3,3-pentamethyldisilazane (1) can be replaced by alkali atoms yielding the derivatives 2 (Li), 3 (Na), 4 (K), and 5 (Rb). All molecules are dimeric in solution as well as in the crystal (not investigated for 2), 4 and 5 forming isotypic crystal structures. According to X-ray structure analysis the structure of the sodium derivative is fundamentally different from that of the corresponding potassium and rubidium one: the tricyclic system in 3 consists of three four-membered rings sharing edges and one common corner (2 x NaNSiO, 1 x Na2N2), and belongs to the point symmetry C2 (2), while the tricycle in 4 has exclusively edge-sharing four-membered rings (2 x KNSiO, 1 x K2N2) and has a Ci (I) symmetry element. In the first case the two sodium atoms have different coordination numbers (c.n. = 4 and 2), in the second one the two potassium atoms are alike (c.n. = 3). As expected, the lower coordinated sodium atom Na(2) exhibits shorter distances to the nitrogen than the tetrahedrally coordinated Na(1) [Na(1)-N 2.467(5), Na(2)-N 2.399(5) Å]. The distances from the oxygen and nitrogen atom to potassium within 4 are long, which can be attributed to the unusual trigonal pyramidally coordinated metal atom. The 1H-NMR spectra of toluene solutions of 2-5 are consistent with bond fluctuation within the molecules.
    Notes: In 1-tert-Butoxy-1,1,3,3,3-pentamethyldisilazan (1) läßt sich das Aminwasserstoffatom durch Alkalimetall-Atome ersetzen, was zu den Derivaten 2 (Li), 3 (Na), 4 (K) und 5 (Rb) führt. Alle Verbindungen liegen in Lösung und im Kristall (bei 2 nicht untersucht) als Dimere vor, wobei 4 und 5 isotype Kristallstrukturen besitzen. Nach Röntgenstrukturanalysen unterscheidet sich die Struktur des Natriumderivates grundlegend von derjenigen der entsprechenden Kalium- bzw. Rubidiumverbindung: in 3 besteht der Tricyclus aus drei kantenverknüpften Vierringen (2 x NaNSiO, 1 x Na2N2), die eine gemeinsame Ecke und die Punktsymmetrie C2 (2) besitzen, während der Tricyclus in 4 ausschließlich aus kantenverknüpften Vierringen aufgebaut ist (2 x KNSiO, 1 x K2N2), aber das Symmetrieelement Ci (I) enthält. Im ersten Fall besitzen die beiden Natriumatome unterschiedliche Koordinationszahlen (KZ = 4 und 2), im zweiten Fall sind die Kaliumatome gleichartig (KZ = 3). Erwartungsgemäß kommt dem niedriger koordinierten Natriumatom Na(2) ein kürzerer Abstand zum Stickstoff zu als dem tetraedrisch koordinierten Na(1) [Na(1)-N 2.467(5), Na(2)-N 2.399(5) Å]. Die Abstände des Stickstoff- und Sauerstoffatoms zum K in 4 sind lang und können mit der ungewöhnlichen trigonal pyramidalen Koordination um das Metallatom erklärt werden. Die 1H-NMR-Spektren der Toluollösungen von 2-5 deuten auf Fluktuationen innerhalb der Moleküle hin.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19891220403
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  • 6
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    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 
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    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.
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    URL: http://dx.doi.org/10.1002/cber.19891220508
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  • 7
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    Darstellung und Struktur von Alkali-penta-tert-butoxystannaten(IV) (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1941-1944 
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    ISSN: 0009-2940
    Keywords: Alkali alkoxystannates(IV) ; Mixed metal alkoxides ; Tin(IV), pentavalent ; Coordination polymers, helical ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation and Structure of Alkali Penta-tert-butoxystannates(IV)Potassium, rubidium, and caesium tert-butoxide react with tin tetra-tert-butoxide in toluene to form compounds MSn(OtBu)5 [M=K(2), Rb (3), Cs (4)] in contrast to lithium and sodium tert-butoxide. The compounds 2-4 are soluble in non-coordinating solvents and seem to be almost monomeric. 2 crystallizes as 2 · 1/2 toluene in the orthorhombic space group Fddd. The X-ray structure determination shows 2 to be coordinated as a helical polymer with the tin atom in the center of a trigonal bipyramid of tert-butoxide groups interlinked by two structurally different potassium atoms.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19901231003
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  • 8
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    Cyclische Diazastannylene, XIII. [SnN2(CH3)2]4 und [SnNCH(CH3)2]4, Moleküle mit Cuban-Struktur (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2141-2152 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclic Diazastannylenes, XIII. [SnN2(CH3)2]4 and [SnNCH(CH3)2]4, Molecules with Cubane-like Structures1,3-Di-tert-butyl-2,2-dimethyl-1,3,2,4λ2-diazasilastannetidine (1) reacts in benzene with N,N-dimethylhydrazine spontanously and with isopropylamine after warming shortly to yield N,N′-di-tert-butyl-Si,Si-dimethylsilazane (2) and the tetrameric molecules (SnN2Me2)4 (5) and (SnNCHMe2)4 (6). An X-ray structure determination (R = 0.026) proves 5 to be built of a very distorted Sn4N4-cube, the nitrogen atoms being attached to dimethylamino groups. In the crystal the molecules are linked together by Sn—Sn contacts (351 pm) forming a zick-zack band, which runs in the direction of the hexagonal axis. Typical Sn—N bond lengths are found to be 220.9 and 225.1 pm, while the mean N—N distance is 146.2 pm. When heated or by contact with oxygen the crystals of 5 decompose vehemently: the products are found to be β-tin, molecular nitrogen, and varying amounts of methane, ethane, and dimethylamine (by contact with oxygen small amounts of tin(II)-oxide are formed as well).
    Notes: 1,3-Di-tert-butyl-2,2-dimethyl-1,3,2,4λ2-diazasilastannetidin (1) reagiert in Benzol mit N,N-Dimethylhydrazin spontan und mit Isopropylamin nach kurzem Erwärmen zu N,N′-Di-tert-butyl-Si,Si-dimethylsilazan (2) und den Tetrameren (SnN2Me2)4 (5) und (SnNCHMe2)4 (6). Eine Röntgenstrukturbestimmung (R = 0.026) zeigt, daß 5 einen stark verzerrten Sn4N4-Kubus besitzt, an dessen Stickstoffatome Dimethylaminogruppen gebunden sind. Im Kristall sind die Moleküle über Sn—Sn-Kontakte (351 pm) zu einem Zickzack-Band verknüpft, das in Richtung der hexagonalen Achse verläuft. Typische Sn—N-Bindungslängen liegen bei 220.9 und 225.1 pm, während für N—N 146.2 pm ermittelt werden. Beim Erhitzen sowie bei Sauerstoffzufuhr zersetzen sich die Kristalle von 5 heftig: als Produkte erhält man β-Zinn, molekularen Stickstoff und in wechselnden Mengen Methan, Ethan und Dimethylamin (bei Sauerstoffeinwirkung auch geringe Mengen an Zinn(II)-oxid).
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    URL: http://dx.doi.org/10.1002/cber.19821150611
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  • 9
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    Additionsreaktionen an intramolekular basenstabilisierte Ge=N- und Ge=S-Doppelbindungen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1135-1141 
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    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.
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    URL: http://dx.doi.org/10.1002/cber.19911240524
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  • 10
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    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 
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    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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