Molecular weight control in organochromium olefin polymerization catalysis by hemilabile ligand–metal interactions

• Stefan Mark,
• Hubert Wadepohl and
• Markus Enders

Beilstein J. Org. Chem. 2016, 12, 1372–1379, doi:10.3762/bjoc.12.131

• polymerization. All complexes investigated show very high catalytic activity and the additional side arm minimizes chain-transfer reactions, leading to increase of molecular weights of the resulting polymers. Keywords: chromium single-site catalysts; olefin polymerization; ultra-high molecular weight

• external donors (e.g., solvent molecules, substrates, additives, etc.) may displace a relatively strong intramolecular donor function. Several examples for olefin polymerization catalysts with hemilabile ligands are known and the impact of the hemilabile group on the polymerization behavior can be immense

• role in olefin polymerization [18][19][20][21][22][23][24]. Cyclopentadienyl (Cp)-based chromium complexes exhibit very good ethylene polymerization properties, when the coordination sphere of the chromium center is completed by an additional ligand. Improved stability and hence polymer productivities

Attempts to prepare an all-carbon indigoid system

• Şeref Yildizhan,
• Henning Hopf and
• Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 363–372, doi:10.3762/bjoc.11.42

• employed for olefin polymerization [26][27]. Since compound 23 contains doubly activated methylene positions, it should be easy to alkylate or bis-alkylate it. Furthermore, use of a bis-electrophile such as 1,2-dibromoethane could lead to the [2.2]indenophane 26 or its isomer 27, both potential ligands for

Micro-flow synthesis and structural analysis of sterically crowded diimine ligands with five aryl rings

• Shinichiro Fuse,
• Nobutake Tanabe,
• Akio Tannna,
• Yohei Konishi and
• Takashi Takahashi

Beilstein J. Org. Chem. 2013, 9, 2336–2343, doi:10.3762/bjoc.9.268

• reported, and they are useful with late transition metal olefin-polymerization catalysts [18][19], and for the stabilization and isolation of reactive metal species [20][21]. In 1997, Murillo and coworkers reported the synthesis of a neutral, and bulky chelating ligand 1, and its use in the formation of a