Infrared Spectroscopic Analysis of Linkage Isomerism in Metal−Thiocyanate Complexes

Abstract

We developed an experiment suitable for an advanced inorganic chemistry laboratory that utilizes a cooperative learning environment, which allows students to develop an empirical method of determining the bonding mode of a series of unknown metal−thiocyanate complexes. Students synthesize the metal−thiocyanate complexes and obtain the FT-IR spectrum of each one, along with reference complexes of known coordination. They are then asked to develop a quantitative approach of comparing the unknown metal−thiocyanate complexes to the references and deduce the most feasible bonding mode of each metal to the thiocyanate ligand, whether via the sulfur or nitrogen atom. The students can then explain their results using hard−soft acid−base concepts.

Synthesis, Crystal Structures and Magnetic Properties of Mononuclear High-Spin Cobalt(II) Complex

“…If the value was~2050 cm −1 , then nitrogen bonded, while greater than~2100 cm −1 implied the sulpher complex bonded with thiocyanate group. The ν(CN) band was found at 2071 cm −1 and is indicative of nitrogen coordination in complex 1 rather than sulphur coordination to Co(II) ion (terminal N-bonded) [32]. Bands related to the phen ligand were observed at 1638, 1592, 1541 and 1511 cm −1 , as reported by others [33,34].…”

Ni(II) N-(2-Pyridylmethyl)-L-Alanine) Complex: Structural Diversity and Photoluminiscent Studies

“…This band confirms the formation of imine (-C=N) group of Schiff bases which was reduced during the synthesis by NaBH 4 /H 2 O to the amine group -N-H. Furthermore the IR spectra of the ligand revealed a strong absorption band at 1672 cm −1 due to ν (C=C, C=N) stretching of the pyridyl group [27]. This band in the metal complex shifted to 1577 cm −1 and 1597 cm −1 .…”

Tuning Intercrystalline Void-like Defects in Nanowire Clusters to TiO2 Quantum Wires with Enhanced Photocatalytic Performance

“…The vibrational stretching frequencies for both dye-treated SMoQWs and NCNWs occur at 2116 cm −1 which establishes that metal binding is coordinated via the C−N bond. 39 However, the absorption band previously identified around 1998 cm −1 but observed here as the broader shoulder of peak 2116 cm −1 (Figure 10) is associated with N− S binding for SMoQWs and NCNWs. 40 From the peak spectra we conclude that N179 dye is predominately bound via the C−N orientation in both SMoQWs and NCNWs although notably more for SMoQWs showing a distinctive absorption peak at 1995 cm −1 (Figure 10).…”