Issue 23, 2017

A novel family of homoleptic copper(i) complexes featuring disubstituted cyanamides: a combined synthetic, structural, and theoretical study

Abstract

The homoleptic copper(I) complexes [Cu(NCNRR′)4](BF4) (R/R′ = Me/Me 1, Et/Et 2, C5H103, C4H8O 4, C4H85, C3H6C6H46, CH2Ph/CH2Ph 7, Me/Ph 8) featuring disubstituted cyanamides were obtained in excellent (92–97%) yields by the reaction of [Cu(NCMe)4](BF4) and 4 equivalents of NCNRR′. Complexes 1–8 were characterized by atomic absorption spectrometry (Cu%), high resolution ESI+-MS, molar conductivities, TG/DTA, and 1H, 13C{1H} NMR, FTIR spectroscopic techniques, and also by single-crystal X-ray diffraction (1, 3, and 4). Results of DFT calculations and X-ray structure determinations reveal that equilibrium geometries of [Cu(NCMe)4]+ and [Cu(NCNMe2)4]+ in the gas phase are normal tetrahedral (Td) and significantly distorted, respectively. Effects of crystal packing influence the values of the Cu–N–C angles in [Cu(NCNRR′)4]+, which points out to the noticeable contribution of the heterocumulene mesomeric form for the dialkylcyanamide copper(I) complexes. The QTAIM and NBO analyses indicate that relatively weak Cu–N contacts (15–31 kcal mol−1) in both cases exhibit single bond character and clearly polarized toward the N atom (by 91–95%). The CDA shows that the {M} ← L σ-donation substantially prevails over the {M} → L π-back-donation in both [Cu(NCMe)4]+ and [Cu(NCNMe2)4]+. The orbital, charge, and vibrational frequency arguments as well as inspection of the FTIR data suggest that the electrophilic activation of the N[triple bond, length as m-dash]C group in homoleptic nitrile and dialkylcyanamide copper(I) complexes is similar, and the different behavior of nitriles and cyanamides in the 1,3-dipolar cycloaddition of ketonitrones is mainly due to the difference in the atomic charges.

Graphical abstract: A novel family of homoleptic copper(i) complexes featuring disubstituted cyanamides: a combined synthetic, structural, and theoretical study

Supplementary files

Article information

Article type
Paper
Submitted
30 Jul 2017
Accepted
16 Oct 2017
First published
16 Oct 2017
This article is Open Access
Creative Commons BY-NC license

New J. Chem., 2017,41, 14557-14566

A novel family of homoleptic copper(I) complexes featuring disubstituted cyanamides: a combined synthetic, structural, and theoretical study

A. A. Melekhova, A. S. Novikov, T. L. Panikorovskii, N. A. Bokach and V. Yu. Kukushkin, New J. Chem., 2017, 41, 14557 DOI: 10.1039/C7NJ02798B

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, 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 commercial 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