Halogen Bonding Involving Gold Nucleophiles in Different Oxidation States

Irina S Aliyarova; Elena Yu Tupikina; Natalia S Soldatova; Daniil M Ivanov; Pavel S Postnikov; Mekhman Yusubov; Vadim Yu Kukushkin

doi:10.1021/acs.inorgchem.2c01858

Halogen Bonding Involving Gold Nucleophiles in Different Oxidation States

Inorg Chem. 2022 Oct 3;61(39):15398-15407. doi: 10.1021/acs.inorgchem.2c01858. Epub 2022 Sep 22.

Authors

Irina S Aliyarova^{1

2}, Elena Yu Tupikina¹, Natalia S Soldatova², Daniil M Ivanov^{1

2}, Pavel S Postnikov^{2

3}, Mekhman Yusubov², Vadim Yu Kukushkin^{1

4}

Affiliations

¹ Institute of Chemistry, Saint Petersburg State University, Universitetskaya Nab. 7/9, Saint Petersburg 199034, Russian Federation.
² Research School of Chemistry and Applied Biomedical Sciences, Tomsk Polytechnic University, Tomsk 634034, Russian Federation.
³ Department of Solid State Engineering, Institute of Chemical Technology, Prague 16628, Czech Republic.
⁴ Institute of Chemistry and Pharmaceutical Technologies, Altai State University, 656049 Barnaul, Russian Federation.

PMID: 36137295
DOI: 10.1021/acs.inorgchem.2c01858

Abstract

A single-crystal X-ray diffraction (XRD) study of diaryliodonium tetrachloroaurates (or, in the recent terminology, tetrachloridoaurates), [(p-XC₆H₄)₂I][AuCl₄] (X = Cl, 1; Br, 2), was performed for 1 (the structure is denoted as 1a to show similarity with the isomorphic structure 2a) and two polymorphs─2a (obtained from MeOH) and 2b (from 1,2-C₂H₄Cl₂). Examination of the XRD data for these three structures revealed 2-center C-X···Au^III (X = Cl and Br) and 3-center bifurcated C-Br···(Cl-Au) halogen bonding (abbreviated as XB) between the p-Cl or p-Br atoms of the diaryliodonium cations and the gold(III) atom of [AuCl₄]^-. The noncovalent nature of Au^III-involving interactions, the nucleophilicity of the gold(III) atoms, and the electrophilic role of p-X atoms of the diaryliodonium cations in the XBs were studied by a set of complementary computational methods. Combined experimental and theoretical studies allowed the recognition of the d-nucleophilicity of the [d⁸Au^III] atom which, regardless of its rather substantial formal 3+ charge, can function as a d-nucleophilic partner of XB. This conclusion was also supported by theoretical calculations performed for the structures' refcodes BINXOM and ICSD 62511; the obtained data verified the nucleophilicity of Au^III toward a K⁺ ions or a σ-(Cl)-hole, respectively. All our results, together with consideration of relevant literature, indicate that gold atoms in the three oxidation states (0, I, and even III) exhibit nucleophilicity in XBs.