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  • Magnesium, N,N′-Bis(trimethylsi yl)benzamidinate  (1)
  • Tin  (1)
  • Transmetalation  (1)
  • 1
    ISSN: 0044-2313
    Keywords: Magnesium, N,N′-Bis(trimethylsi yl)benzamidinate ; synthesis ; spectroscopic data ; structure of magnesium bis[N,N′-bis(trimethylsilyl)benzamidinate] ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Magnesium Bis[N,N′ -bis(trimethylsilyl)benzamidinate] as both Bis(THF) and Benzonitrile AdductMagnesium bis[bis(trimethylsilyl)amide] 1, reacts with benzonitrile in toluene at room temperature to yield magnesium bis[N,N′-bis(trimethylsilyl)benzamidinate]-benzonitrile(1/1) 2. Addition of THF leads to a quantitative substitution of the benzonitrile ligand by two THF molecules. The performance of the addition reaction in THF yields magnesium bis[N,N′-bis(trimethylsilyl)benzamidinate] · THF(1/2) 3. The upper benzonitrile complex 2, crystallizes in the orthorhombic space group Pbcn with {a = 1383.2(2); b = 2589.1(4); c = 1133.7(1) pm; Z = 4}. The magnesium atom is coordinated distorted trigonal-bipyramidal, where the benzonitrile ligand lies within the equatorial plane. The axial bound nitrogen atom of the benzamidinate substitution shows with a value of 213 pm a slightly longer bond distance to the metal center than the one in the equatorial plane (210 pm). The steric strain within the benzamidinate ligand leads to an elongation of the silicon atoms out of the 1,3-diazaallylic moiety under an enlargement of the C—N—Si angle to 131°.
    Notes: Magnesium-bis[bis(trimethylsilyl)amid] 1, reagiert mit Benzonitril in Toluol bei Zimmertemperatur zu Magnesium-bis[N,N′-bis(trimethylsilyl)benzamidinat]-Benzonitril(1/1) 2. Der Benzonitriligand läßt sich durch Zugabe von THF quantitativ durch zwei Ethermoleküle ersetzen. Auch die Durchführung der Additionsreaktion in THF führt zum Magnesium-bis [N,N′ -bis(trimethylsilyl)benzaminidat]-THF(1/2) 3. Der erstgenannte Benzonitril-Komplex 2, kristallisiert in der orthorhombischen Raumgruppe Pbcn mit {a = 1383,2(2); b = 2589,1(4); c = 1133,7(1) pm; Z = 4}. Das Magnesiumatom weist verzerrt trigonal-bi-pyramidale Umgebung auf, wobei sich der Benzonitrilligand in der äquatorialen Ebene anordnet. Das in der axialen Position befindliche Stickstoffatom des Benzamidinat-Substituenten weist mit 213 pm einen um etwa 3 pm größeren Abstand zum Metallzentrum auf als dasjenige in der äquatorialen Ebene. Die sterischen Spannungen innerhalb des Benzamidinat-Liganden führen zur Auslenkung der Siliciumatome aus der 1,3-Diazaallylebene unter gleichzeitiger C—N—Si-Winkelaufweitung auf 131°.
    Additional Material: 3 Ill.
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  • 2
    ISSN: 0044-2313
    Keywords: Transmetalation ; Calcium, Stannylene ; Tin ; Amide ; NMR Spectroscopy, X-Ray Structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Substituted Calcium-bis(disilylamides) by Transmetalation of Tin(II) and Tin(IV) AmidesStannylenes as well as stannanes with substituted disilylamino groups are valuable synthons for the synthesis of alkaline earth metal bis(disilylamides) via the transmetallation reaction. Whereas bis[2,2,5,5-tetramethyl-2,5-disilaaza-cyclo-pentyl]stannylene 1 is a suitable reagent for this type of reaction, bis[trimethylsilyl-tris(trimethylsilyl)silylamino]stannylene 2 (monoclinic, P21/c, a = 1492.6(2), b = 1705.2(2), c = 1865.3(3) pm, β = 109.03(2)º, Z = 4) is not only attacked at the Sn—N-bond but also the N—Si-bond is cleaved by calcium metal. Similar light sensitivity as for 2 is observed for the mercury bis[trimethylsilyl-tris(trimethylsilyl)silylamide] 3, the homolytic M—N-bond cleavage leads to the formation of the trimethylsilyl-tris(trimethylsilyl)silylamino radical (g = 2.00485; a(N) = 16.2 G). The calcium tin exchange reaction of 1 in THF yields tris(tetrahydrofuran-O)calcium-bis[2,2,5,5-tetramethyl-2,5-disilaaza-cyclo-pentanide] 4 (monoclinic, P21/n, a = 1060.9(2), b = 1919.3(5), c = 1686.0(3) pm, β = 90.30(2)º, Z = 4). The stannanes Men-4Sn[N(SiMe3)2]n with n = 1 or 2 are also valuable materials for the synthesis of bis(tetrahydrofuran-O)calcium-bis[bis(trimethylsilyl)amide].
    Notes: Stannylene und Stannane mit substituierten Disilylamino-Substituenten eignen sich als Edukte für die Transmetallierungsreaktion zur Synthese von Calcium-bis(disilylamiden). Anwendung fanden Bis[2,2,5,5-tetramethyl-2,5-disilaaza-cyclo-pentyl]stannylen 1 und Bis[trimethylsilyl-tris(trimethylsilyl)silylamino]stannylen 2 (monoklin, P21/c, a = 1492,6(2), b = 1705,2(2), c = 1865,3(3) pm, β = 109,03(2)º, Z = 4). Bei der Verwendung von 2 greift das destillierte Calcium allerdings nicht nur die Sn - N-, sondern auch die N—Si-Bindung an. Ähnlich wie bei dem Quecksilber-bis[trimethylsilyl-tris(trimethylsilyl)silylamid] 3 beobachtet man bereits bei Tageslicht die homolytische Spaltung der Sn—N- bzw. Hg—N-Bindung und die Bildung des Trimethylsilyl-tris(trimethylsilyl)silylamino-Radikals 5 (g = 2,00485; a(N) = 16,2G). Der heterogen geführte Zinn-Calcium-Austausch bei Verbindung 1 in THF führt in guten Ausbeuten zum Tris(tetrahydrofuran-O)calcium-bis[2,2,5,5-tetramethyl-2,5-disilaaza-cyclo-pentanid] 4 (monoklin, P21/n, a = 1060,9(2), b = 1919,3(5), c = 1686,0(3) pm, β = 90,30(2)º, Z = 4). Auch die Stannane Men-4Sn[N(SiMe3)2]n mit n = 1 oder 2 eignen sich als Synthone zur Synthese von Bis(tetrahydrofuran-O)calcium-bis[bis(trimethylsilyl)amid].
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