Issue 41, 2022

Indium(iii)/2-benzoylpyridine chemistry: interesting indium(iii) bromide-assisted transformations of the ligand

Abstract

Reactions of 2-benzoylpyridine, (py)(ph)CO, with InX3 (X = Cl, Br) in EtOH at room temperature have been studied. The InCl3/(py)(ph)CO system has provided access to complex [InCl3{(py)(ph)CO}(EtOH)]·{(py)(ph)CO} (1) and the byproduct {(pyH)(ph)CO}Cl (2). The reaction of InBr3 with (py)(ph)CO has led to a mixture of (L)[InBr4{(py)(ph)CO}] (3) and [In2Br4{(py)(ph)CH(O)}2(EtOH)2] (4), where L+ is the 9-oxo-indolo[1,2-a]pyridinium cation and (py)(ph)CH(O) is the anion of (pyridin-2-yl)methanol. Based on solubility and crystallisation time differences between the two components of the mixture, complex 4 was isolated in pure form, i.e. free from 3. The formations of the counterion L+ and the coordinated (py)(ph)CH(O) anion represent clearly InBr3-promoted/assisted transformations. Reaction mechanisms have been proposed for the formation of 2, 3 and 4. Complex 4 could also be isolated by the reaction of InBr3 and pre-formed (py)(ph)CH(OH) in EtOH. The solid-state structures of 1, 3 and 4 were determined by single-crystal X-ray crystallography, while the identity of the salt 2 was confirmed by microanalyses and a variety of spectroscopic techniques, including ESI-MS spectra. In the indium(III) complexes, the metal ions are 6-coordinate with a distorted octahedral geometry. The halogeno groups (Cl, Br) in the three complexes are terminal. The (py)(ph)CO molecule behaves as a N,O-bidentate (1.11) ligand in 1 and 3. A terminal EtOH ligand completes the coordination sphere of InIII in 1. The alkoxo oxygen atoms of the two 2.21 (py)(ph)CH(O) ligands doubly bridge the InIII centers in 4 creating a {InIII2(μ-OR)2}4+ core; a nitrogen atom of one reduced organic ligand, two bromo ions and one terminal EtOH molecule complete the 6-coordination at each metal centre. Complexes 1, 3 and 4 were characterised by IR and Raman spectroscopies, and the data were discussed in terms of their known solid-state structures. Molar conductivity data and 1H NMR spectra were used in an attempt to probe the behaviour of the complexes in DMSO. The to-date observed metal ion-assisted/promoted transformations of (py)(ph)CO are also discussed.

Graphical abstract: Indium(iii)/2-benzoylpyridine chemistry: interesting indium(iii) bromide-assisted transformations of the ligand

Supplementary files

Article information

Article type
Paper
Submitted
31 Aug. 2022
Accepted
27 Sept. 2022
First published
28 Sept. 2022
This article is Open Access
Creative Commons BY license

Dalton Trans., 2022,51, 15771-15782

Indium(III)/2-benzoylpyridine chemistry: interesting indium(III) bromide-assisted transformations of the ligand

C. Stamou, Z. G. Lada, C. T. Chasapis, D. Papaioannou, P. Dechambenoit and S. P. Perlepes, Dalton Trans., 2022, 51, 15771 DOI: 10.1039/D2DT02851D

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