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Open AccessFeature PaperArticle

In Silico Acetylene [2+2+2] Cycloadditions Catalyzed by Rh/Cr Indenyl Fragments

Dipartimento di Scienze Chimiche Universita’ degli Studi di Padova, Via Marzolo 1, 35131 Padova, Italy
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Catalysts 2019, 9(8), 679; https://doi.org/10.3390/catal9080679
Received: 20 July 2019 / Revised: 7 August 2019 / Accepted: 8 August 2019 / Published: 9 August 2019
(This article belongs to the Special Issue Advanced Strategies for Catalyst Design)
Metal-catalyzed alkyne [2+2+2] cycloadditions provide a variety of substantial aromatic compounds of interest in the chemical and pharmaceutical industries. Herein, the mechanistic aspects of the acetylene [2+2+2] cycloaddition mediated by bimetallic half-sandwich catalysts [Cr(CO)3IndRh] (Ind = (C9H7), indenyl anion) are investigated. A detailed exploration of the potential energy surfaces (PESs) was carried out to identify the intermediates and transition states, using a relativistic density functional theory (DFT) approach. For comparison, monometallic parent systems, i.e., CpRh (Cp = (C5H5), cyclopentadienyl anion) and IndRh, were included in the analysis. The active center is the rhodium nucleus, where the [2+2+2] cycloaddition occurs. The coordination of the Cr(CO)3 group, which may be in syn or anti conformation, affects the energetics of the catalytic cycle as well as the mechanism. The reaction and activation energies and the turnover frequency (TOF) of the catalytic cycles are rationalized, and, in agreement with the experimental findings, our computational analysis reveals that the presence of the second metal favors the catalysis. View Full-Text
Keywords: acetylene [2+2+2] cycloadditions; DFT calculations; rhodium; chromium; half-sandwich catalysts; turnover frequency (TOF); activation strain analysis; indenyl effect; metal slippage; slippage span model acetylene [2+2+2] cycloadditions; DFT calculations; rhodium; chromium; half-sandwich catalysts; turnover frequency (TOF); activation strain analysis; indenyl effect; metal slippage; slippage span model
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MDPI and ACS Style

Masood Ahmad, S.; Dalla Tiezza, M.; Orian, L. In Silico Acetylene [2+2+2] Cycloadditions Catalyzed by Rh/Cr Indenyl Fragments. Catalysts 2019, 9, 679.

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