Structure and stability of coinage metal fluoride and chloride clusters (M_nF_n and M_nCl_n, M = Cu, Ag, or Au; n = 1–6)

Abstract

Calculations in the framework of the density functional theory are performed to study the lowest-energy isomers of coinage metal fluoride and chloride clusters (M(n) F(n) , M(n) Cl(n) , M = Cu, Ag, or Au, n = 1-6). For all calculated species starting from the trimers the most stable structures are found to be cyclic arrangements. However, planar rings are favored in the case of metal fluorides whereas metal chlorides prefer nonplanar cycles. Calculated bond lengths and infrared frequencies are compared with the available experimental data. The nature of the bonding, involving both covalent and ionic contributions, is characterized. The stability and the fragmentation are also investigated. Trimers are found to be particularly stable when considering the Gibbs free energies.

Electron density properties and metallophilic interactions of gold halides AuX2and Au2X (X = F–I):Ab Initiocalculations

“…Metal clusters have attracted much experimental and theoretical research interest in the past few decades. Certain clusters consisting of a metal atom surrounded by electronegative atoms can display “superatom” behavior . These clusters, also known as “superhalogens,” can possess electron affinities (EA) that are even larger than that of a Cl atom, which has the highest EA in the periodic table.…”

Investigation into the metallophilic interaction in coinage-metal halides: an ab initio study of CMX (CM = Cu and Ag, X = F − I)

“…Rabilloud [9,10] reported values of 1.755/(2.00), 2.090/(2.33), 2.220/(2.44) and 2.390/(2.67) Å at B3LYP theoretical level with an spd function basis set (in their research, f-type functions were found not to give significant changes and so were not used). For binding energies, E b , the available experimental values of CuF, AgF and AgBr were 4.46, 3.64 and 2.88 eV; our CCSD(T) results are 4.43, 3.52 and 3.01 eV, while Rabilloud reported B3LYP values of 3.75, 3.05 and 2.60 eV.…”

“…The question then arises if CM-halides are also covalent in character. The existence of d electrons in CMs makes theoretical investigations much more complicated, and the nature of CM-halide interactions remains controversial [9,10]. By analyzing electron localization function (ELF) results [11], Liu and coworkers [12] reported a strong ionic character in Au-F bonding and an increased covalent character from Au-Cl to Au-I in the [XAuCN] − (X=F−I) series.…”

AuRnX and XAuRn (X=F ‐ I and OH)

“…An excellent review by Bellert and Breckenridge suggested that the XeAu + is described by a covalent bonding through an electrostatic model, while the nature of other NGAu + interactions is left undecided. Meanwhile, CM‐halides have also attracted many interests in terms of both experimental and theoretical investigations . Generally, the metal‐halides show ionic bonding characteristics.…”

“…And obvious covalent bonding characteristics have been observed in Au‐containing compounds . Then the question arises whether the Au‐halides may in fact contain covalent characters and its nature is still controversial . Electron localization function (ELF) analyses on [XAuCN] − (X=F‐I) and MI 2 − (M=Cs, Cu, Au) found a strong ionic character in Au−F bonding and increased covalence from Au−Cl to Au‐I .…”