Rational design of ansa-heterocenes with a long SiOSi bridge as a catalysts for selective dimerization of oct-1-ene

• Published in: Applied catalysis. A, General Vol. 680; p. 119756
• Main Authors: Kiselev, Artem V., Nifant'ev, Ilya E., Vinogradov, Alexander A., Vinogradov, Alexey A., Bagrov, Vladimir V., Afanaseva, Anna V., Minyaev, Mikhail E., Ivchenko, Pavel V.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 25.06.2024
• Subjects: 5,6-dihydroindeno[2,1-b]indole; Dimerization; Methylenealkanes; Zirconocenes; α-olefins; Methylenealkanes; Zirconocenes; 5,6-dihydroindeno[2,1-b]indole; α-olefins; Dimerization
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2024.119756

Being activated by methylalumoxane ([Al]/[Zr] = 10), (η5-C5H5)2ZrCl2 (Zr1) and [(η5-C5H4SiMe2)2O]ZrCl2 (Zr2) catalyze selective dimerization of α-olefins with low productivity (turnover number TON ∼2000). Our previous research of heterocycle-fused ansa-zirconocenes revealed that SiMe2-bridged complexes catalyze polymerization of α-olefins, whereas CH2CH2-bridged complexes are high-performance oligomerization catalysts (TON ∼ 4∙105). We proposed that further elongation of the bridge will allow obtaining dimerization catalysts. New –SiMe2OSiMe2– bridged ansa-zirconocenes Zr3–Zr11 were synthesized and studied in oct-1-ene dimerization at 100 °C and [oct-1-ene]/[Zr] ratio of 3∙104. In the absence of H2 bis(5,6-dihydroindeno[2,1-b]indole) derivatives Zr8 and Zr9 demonstrated high activity and dimerization selectivity up to 94%. In the presence of H2 symmetrical indenoindole complexes Zr5–Zr9 appeared to be even more active, but up to 24% of hydrogenated oct-1-ene dimer HC16 was formed. Mixed-ligand complexes Zr10 and Zr11 catalyzed oct-1-ene dimerization with up to 99% selectivity without the formation of HC16 even in trace amounts. [Display omitted] •Synthesis and structure of new –SiMe2OSiMe2– bridged Zr(IV) ansa-complexes.•Derivatives of fluorene, cyclopentadithiophene and isomeric indenoindoles.•Study of oct-1-ene dimerization using MMAO-12 and [PhNMe2H][B(C6F5)4] activators.•5,6-Dihydroindeno[2,1-b]indole-based heterocenes are efficient in the absence of H2•In H2 mixed-ligand fluorenyl complexes catalyze dimerization without hydrogenolysis.