Butenylsubstituierte Erdalkalimetallocene: ein erster Schritt zu Olefinkomplexen der Erdalkalimetalle

Abstract

Sandwich gefällig? Eine Wechselwirkung der Erdalkalimetalle mit Olefindoppelbindungen zeigen die Bis(butenyltetramethylcyclopentadienyl)komplexe von Calcium (2), Strontium und Barium. Während das Magnesiumderivat (1) als Sandwichkomplex mit coplanaren Cyclopentadienylliganden und freien Butenylseitenketten kristallisiert, koordinieren diese in den analogen, aber offenen Sandwichkomplexen der größeren Metalle Calcium, Strontium und Barium an das Metall.

Sodium Cation Migration Above the Diimine π‐System of Solvent Coordinated dpp‐BIAN Sodium Aluminum Complexes (dpp‐BIAN=1,2‐Bis[(2,6‐diisopropylphenyl)imino]acenaphthene)

“…In the complexes 2 and 3, the sodium cation additionally coordinates the toluene (2) Recently, the first olefin complexes of alkaline earth metals were synthesized and structurally characterized. [5] The coordination of the olefin to the alkaline earth metal center has been confirmed not only crystallographically but also by means of 1 H NMR spectroscopy. For several years, we have been interested in the preparation and reactivity of 1,2-bis[(2,6-diisopropylphenyl)imino]-A C H T U N G T R E N N U N G acenaphthene (dpp-BIAN) complexes of main-group metals.…”

“…The molecular structures of 1-5 have been determined by single-crystal X-ray diffraction. The sodium cation coordinates either one of the naphthalene rings (1) or the diimine part of the dpp-BIAN ligand (2)(3)(4)(5). In the complexes 2 and 3, the sodium cation additionally coordinates the toluene (2) Recently, the first olefin complexes of alkaline earth metals were synthesized and structurally characterized.…”

Aktivierung einer an Zink gebundenen Ethylgruppe durch Bildung eines Zn‐CEt‐Ba‐Fragments und Kristallstruktur von [((Me3Si)2N)Ba(thf)Zn2(μ‐Et)(μ3‐PSitBu3)2]2 mit verbrückenden Ethyl‐Substituenten

“…[7] Die Ba-C-Bindungslängen in 3 liegen im oberen Bereich verglichen mit Molekülen mit p-gebundenen Liganden mit ausgeprägter Ladungsdelokalisation [13,14] oder mit "side-on" koordinierten Alken-Einheiten. [15] Ein Vergleich der Ba-P-Abstände in 3 (323.2(5) und 333.9(5) pm) und 2 a (313.9(1) pm) zeigt, dass die Bindungen in 3 trotz der niedrigeren Koordinationszahl länger sind. Die Ursache hierfür ist der starke räumliche Anspruch der Substituenten.…”

Ultrasonic oscillations effect on rheological and processing properties of metallocene‐catalyzed linear low density polyethylene

“…These CaO distances are slightly longer than those in the reported eight‐coordinated calcium metallocenes 4 (2.412 and 2.401 Å) and 5 (2.400 and 2.417 Å)8b,d and about 0.1 Å longer than that in the six‐coordinated [{(Cp 4i )Ca(μ‐I)(THF)} 2 ] (Cp 4i =tetraisopropylcyclopentadienyl) complex (2.341 Å) 15. Compared with the CaCp (centroid) distances in the reported calcium metallocenes 5 (2.382 and 2.379 Å) and 6 (2.382 and 2.412 Å),8d,e the corresponding distances in 10 d⋅ THF are also longer (2.470 and 2.494 Å), which may be explained in terms of the steric and electronic effects of the substituents attached to the Cp rings. As a consequence, the complex 10 d⋅ THF has a larger coordination sphere, and can easily be coordinated by an additional polar solvent molecule such as THF or Et 2 O.…”

“…As shown in Scheme , cyclopentadienyl ligands bearing donor‐functionalized pendants, such as amine and pyridyl ( 1 , 2 ),8a,b methoxy ( 3 , 4 , 5 ),8b–d and alkenyl ( 6 )8e groups, have been successfully applied for the synthesis of heavier alkaline earth (Ca, Sr, Ba) complexes. Intramolecular coordination of the pendant groups to the metal centers has been confirmed by single‐crystal X‐ray structural analysis 8b,d,e. However, although some progress has been made by using the above‐mentioned ligands, diversity among the cyclopentadienyl ligands and their pendant groups remains very limited.…”