Electron-Deficient Ru(II) Complexes as Catalyst Precursors for Ethylene Hydrophenylation

Inorganics

W. Dean Harman¹  Songyuan Tian¹  T. Brent Gunnoe¹  Philip J. Shivokevich¹  Xiaofan Jia¹  Diane A. Dickie¹ 

[1] Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA;

关键词: olefin hydroarylation;    ruthenium;    catalysis;    ethylbenzene;    C–H activation;   

DOI  :  10.3390/inorganics10060076

来源: DOAJ

【 摘 要 】

Ruthenium(II) complexes with the general formula TpRu(L)(NCMe)Ph (Tp = hydrido(trispyrazolyl)borate, L = CO, PMe₃, P(OCH₂)₃CEt, P(pyr)₃, P(OCH₂)₂(O)CCH₃) have previously been shown to catalyze arene alkylation via Ru-mediated arene C–H activation including the conversion of benzene and ethylene to ethylbenzene. Previous studies have suggested that the catalytic performance of these TpRu(II) catalysts increases with reduced electron-density at the Ru center. Herein, three new structurally related Ru(II) complexes are synthesized, characterized, and studied for possible catalytic benzene ethylation. TpRu(NO)Ph₂ exhibited low stability due to the facile elimination of biphenyl. The Ru(II) complex (Tp^Br3)Ru(NCMe)(P(OCH₂)₃CEt)Ph (Tp^Br3 = hydridotris(3,4,5-tribromopyrazol-1-yl)borate) showed no catalytic activity for the conversion of benzene and ethylene to ethylbenzene, likely due to the steric bulk introduced by the bromine substituents. (Ttz)Ru(NCMe)(P(OCH₂)₃CEt)Ph (Ttz = hydridotris(1,2,4-triazol-1-yl)borate) catalyzed approximately 150 turnover numbers (TONs) of ethylbenzene at 120 °C in the presence of Lewis acid additives. Here, we compare the activity and features of catalysis using (Ttz)Ru(NCMe)(P(OCH₂)₃CEt)Ph to previously reported catalysis based on TpRu(L)(NCMe)Ph catalyst precursors.

【 授权许可】

Unknown