Struktur, Eigenschaften und NMR‐spektroskopische Charakterisierung von Cp₂Zr(Pyridin)(Me₃SiCCSiMe₃)

Abstract

Die Substitution des THF‐Liganden in Cp2Zr(THF)(Me3SiCCSiMe3) (1) durch Pyridin ergibt den Komplex Cp2Zr(η1‐NC5H5)(Me3SiCCSiMe3) (3). Im Gegensatz zu 1 ist Komplex 3 stabil in Kohlenwasserstoffen. In temperaturabhängigen 1H‐ und 13C‐NMR‐Spektren zeigt 3 in Lösung dynamisches Verhalten durch eine Rotation des Alkin‐Liganden. Zusätzlich tritt beim Lösen von 3 in Pyridin ein Austausch zwischen koordinierten und freien Pyridin‐Molekülen auf. Die Kristallstrukturanalyse von 3 belegt eine tetraedrische Koordinationsgeometrie am Zirkonium‐Zentrum bestehend aus den Cp‐, Alkin‐ und Pyridin‐Liganden. Der Komplex 3 reagiert wie Verbindung 1 mit Wasser und Kohlendioxid zu gleichen Produkten.

Reactions of ε-Caprolactone with (Alkyne)zirconocene Complexes: Investigation of Elemental Steps in Catalytic Ring-Opening Polymerization of Lactones

“…After standing for two weeks at Ϫ78°C, red crystals separated which were suitable for X-ray structure analysis (crystals were the pure diastereomer 2a as checked by NMR 7,109.5,110.6,114.7,122.1,122.9,129.3,129.4 (CH) terized example for the formation of such an acetal, which 105.5 (CO), 187.4 (β-CSiMe 3 ), 219.6 (α-CSiMe 3 ). …”

“…[4] For the complexes Cp 2 Zr(L)(η 2 -Me 3 SiC 2 SiMe 3 ) (L ϭ THF, [6] pyridine [7] ) the reaction with acetone, formaldehyde or benzaldehyde [5] leads to insertion products of the carbonyl unit into the zirconacyclopropene ring of the alkyne complex giving zirconadihydrofuranes [Cp 2 Zr{ϪC(SiMe 3 )ϭC(SiMe 3 )ϪCRRЈϪOϪ}], which, in the case of the aldehydes, were additionally stabilized by Complex 2a crystallizes as orange yellow prisms, which,…”

Novel Templating Effect in the Macrocyclization of Functionalized Diynes by Zirconocene Coupling

“…Diyne 1 [4b] (0.370 g, 1.06 mmol) and [Cp 2 Zr(py)(Me 3 SiCCSiMe 3 )] [6] (1.00 g, 2.12 mmol) were loaded into a 100 mL Schlenk flask, which was then charged with dry benzene (50 mL). The flask was sealed, and the reaction mixture was sonicated at room temperature for 10 min.…”

“…The isolated yield was 0.806 g, 96 %; 1 6,127.5,135.5,145.3,149.5,; elemental analysis (%) calcd for C 80 H 88 N 4 Si 4 Zr 4 : C 60.71, H 5.60, N 3.54; found: C 60.57, H 5.32, N 3.39. Macrocycle 4. Diyne 2 [4a] (0.500 g, 0.998 mmol) and [Cp 2 Zr(py)(Me 3 SiCCSiMe 3 )] [6] (0.945 g, 2.01 mmol) were loaded into a 100 mL Schlenk flask, which was then charged with dry benzene (90 mL). The flask was sealed, and the reaction mixture was sonicated at room temperature for 10 min.…”

Rosenthal’s Zirconocene

“…1 Therefore, this complex is treated in situ with pyridine, giving high yields of 2 (up to 85%). 3 This mild reactivity not only allows the reductive coupling of bromide-functionalized alkynes, 6 but also of iodide-substituted species.…”