Raman spectral characterization of silver metal-based complexes of different benzimidazolium ligands

Saqib Ali; Ayesha Riaz; Haq Nawaz; Muhammad Irfan Majeed; Muhammad Adnan Iqbal; Haq Nawaz Bhatti; Nosheen Rashid; Muhammad Kashif; Muhammad Tahir; Saira Nasir; Saif Ullah; Sidra Farooq; Ammara Naseem

doi:10.1016/j.saa.2020.118162

Raman spectral characterization of silver metal-based complexes of different benzimidazolium ligands

Spectrochim Acta A Mol Biomol Spectrosc. 2020 May 5:232:118162. doi: 10.1016/j.saa.2020.118162. Epub 2020 Feb 19.

Authors

Affiliations

¹ Department of Chemistry, University of Agriculture Faisalabad-38040, Pakistan.
² Department of Chemistry, University of Agriculture Faisalabad-38040, Pakistan. Electronic address: haqchemist@yahoo.com.
³ Department of Chemistry, University of Agriculture Faisalabad-38040, Pakistan. Electronic address: irfanmajeed2003@gmail.com.
⁴ Department of Chemistry, University of Agriculture Faisalabad-38040, Pakistan. Electronic address: adnan.iqbal@uaf.edu.pk.
⁵ Department of Chemistry, University of Central Punjab, Faisalabad campus, Faisalabad, Pakistan.

PMID: 32106031
DOI: 10.1016/j.saa.2020.118162

Abstract

In this study, Raman spectroscopy has been employed for the characterization of two structurally different monodentate N-heterocyclic carbene ligands (ligand-1 and ligand-2) and their respective complexes (complex-1 and complex-2). The Raman spectral features are found helpful for the confirmation of formation of complexes. The significant Raman spectral features are identified for benzimidazole ring with higher intensities in carbene complexes having more polarizability as compared to their ligands, providing the evidence for the formation of coordinate covalent bond. The successful complexation is further supported by using multivariate data analysis technique, Principal Component Analysis (PCA), which is found very helpful to highlight the variability of Raman spectral data of both ligands and their respective metal complexes from each other. Moreover, the coordination of carbene with Ag(I) is confirmed from the dominant spectral markers of higher intensities at 359 cm^-1 in complex-1 and 338 cm^-1 in complex-2. The effective and reliable characterization and confirmation of metal complexes indicates the potential of Raman spectroscopy for its use for the characterization of the organometallic complexes and other chemical products.

Keywords: Mono-N-heterocyclic carbene ligands; Principal Component Analysis; Raman spectroscopy; Silver complexes.