Issue 42, 2019

Acetylene and terminal alkyne complexes of copper(i) supported by fluorinated pyrazolates: syntheses, structures, and transformations

Abstract

Trinuclear {μ-[3,5-(CF3)2Pz]Cu}3 reacts with acetylene to produce the 2 : 1 copper(I) acetylene complex, Cu4(μ-[3,5-(CF3)2Pz])4(μ-HC[triple bond, length as m-dash]CH)2. Related Cu4(μ-[4-Br-3,5-(CF3)2Pz])4(μ-HC[triple bond, length as m-dash]CH)2 and Cu4(μ-[4-Cl-3,5-(CF3)2Pz])4(μ-HC[triple bond, length as m-dash]CH)2 have also been isolated using the corresponding copper(I) pyrazolate and acetylene. The 1 : 1 adducts Cu2(μ-[3,5-(CF3)2Pz])2(HC[triple bond, length as m-dash]CH)2 and Cu2(μ-[4-Br-3,5-(CF3)2Pz])2(HC[triple bond, length as m-dash]CH)2 are significantly less stable to the acetylene loss and can be observed in solution at low temperatures under excess acetylene. The X-ray crystal structures of 2 : 1 and 1 : 1 complexes, Cu4(μ-[3,5-(CF3)2Pz])4(μ-HC[triple bond, length as m-dash]CH)2 and Cu2(μ-[4-Br-3,5-(CF3)2Pz])2(HC[triple bond, length as m-dash]CH)2 are reported. Raman data show a reduction in [small nu, Greek, macron]C[triple bond, length as m-dash]C stretching frequency by about ∼340 and ∼163 cm−1 in the 2 : 1 and 1 : 1 Cu(I)/acetylene complexes, respectively, from that of the free acetylene. Copper(I) pyrazolate complexes of the terminal alkynes, phenylacetylene, 1,8-nonadiyne, and 1,7-octadiyne are also reported. They form adducts involving one copper atom on each alkyne moiety. The {μ-[3,5-(CF3)2Pz]Cu}3 is also a very versatile and competent catalyst for alkyne transformations as evident from its ability to catalyze the alkyne C(sp)–H bond carboxylation chemistry with CO2, azide–alkyne cycloadditions leading to 1,2,3-triazoles including the use of acetylene itself as a substrate, and thiol addition to phenylacetylene affording vinyl sulfides.

Graphical abstract: Acetylene and terminal alkyne complexes of copper(i) supported by fluorinated pyrazolates: syntheses, structures, and transformations

Supplementary files

Article information

Article type
Paper
Submitted
16 Aug. 2019
Accepted
05 Sept. 2019
First published
05 Sept. 2019

Dalton Trans., 2019,48, 15782-15794

Acetylene and terminal alkyne complexes of copper(I) supported by fluorinated pyrazolates: syntheses, structures, and transformations

D. Parasar, T. T. Ponduru, A. Noonikara-Poyil, N. B. Jayaratna and H. V. R. Dias, Dalton Trans., 2019, 48, 15782 DOI: 10.1039/C9DT03350E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements