Coordination of Ethylamine on Small Silver Clusters: Structural and Topological (ELF, QTAIM) Analyses

Abstract

Amine ligands are expected to drive the organization of metallic centers as well as the chemical reactivity of silver clusters early growing during the very first steps of the synthesis of silver nanoparticles via an organometallic route. Density functional theory (DFT) computational studies have been performed to characterize the structure, the atomic charge distribution, and the planar two-dimensional (2D)/three-dimensional (3D) relative stability of small-size silver clusters (Ag n , 2 ≤ n ≤ 7), with or without an ethylamine (EA) ligand coordinated to the Ag clusters. The transition from 2D to 3D structures is shifted from n = 7 to 6 in the presence of one EA coordinating ligand, and it is explained from the analysis of the Ag–N and Ag–Ag bond energies. For fully EA saturated silver clusters (Ag n –EA n ), the effect on the 2D/3D transition is even more pronounced with a shift between n = 4 and 5. Subsequent electron localization function (ELF) and quantum theory of atoms in molecules (QTAIM) topological analyses allow for the fine characterization of the dative Ag–N and metallic Ag–Ag bonds, both in nature and in strength. Electron transfer from ethylamine to the coordinated silver atoms induces an increase of the polarization of the metallic core.

Tunable Luminescence of Silver Nanoclusters Confined in SOD/FAU Zeolites and Selective Sensing for Organic Amine

“…The lattice distance of Ag-Y-20 is 0.182 nm (Figure a), matching well with the (995) plane of FAUY, further indicating the integrity of the zeolite framework during the ion exchange and thermal activation. Since HAADF-STEM contrast is proportional to atomic number and thickness, the heavier AgNCs of Ag-Y-20 and Ag-Y-500 appear as white bright spots in the zeolite cages on HAADF-STEM images as shown in Figure b–d, whose size distribution of AgNCs was narrow, that is, in the range of 0.2–0.4 nm, matching well with the size of AgNCs reported previously . It is worth noting that the size distribution of AgNCs in Ag-Y-500 is much more uniform than that in Ag-Y-20, illustrating the homogeneity of the presence of silver species in Ag-Y-500.…”

“…The peaks in 1400–1700 cm –1 are ascribed to the fact that the characteristic vibration of N–H bending of amine molecules appeared in the sample Ag-Y-500 treated with TEA or EA vapor and significantly diminished after exposure to HAc . According to recent reports, ,, the bonding between N and Ag is stronger than that between O and Ag in AgNCs; hence, we infer that the amine molecules might interact with AgNCs via the strong Ag–N interaction as well as result in the breaking of Ag–O F or Ag–O W . To be specific, the stronger coordination between amine molecules and the Ag + in AgNCs might lead to the disintegration or transformation of the self-assembled luminescent clusters, further causing the significant variation of luminescence behavior. , Hence, the strong interaction between different amine molecules and charged AgNCs could cause various changes in electron density of AgNCs, which might lead to the different luminescence responses such as luminescence quenching or different emission colors.…”

“…Since HAADF-STEM contrast is proportional to atomic number and thickness, the heavier AgNCs of Ag-Y-20 and Ag-Y-500 appear as white bright spots in the zeolite cages on HAADF-STEM images as shown in Figure 2b−d, whose size distribution of AgNCs was narrow, that is, in the range of 0.2−0.4 nm, matching well with the size of AgNCs reported previously. 36 It is worth noting that the size distribution of AgNCs in Ag-Y-500 is much more uniform than that in Ag-Y-20, illustrating the homogeneity of the presence of silver species in Ag-Y-500. Unfortunately, we could not obtain the meaningful images for Ag-SOD zeolites because of the high sensitivity of SOD zeolite toward the electron beam.…”

Atoms in molecules in real space: a fertile field for chemical bonding

“…172 Other non-evident or surprising electronic properties have been observed in metalÁ Á Ámetal bonds like the RhÁ Á ÁCr bond in rhodium(I) complexes stabilized by hemichelation (i.e., heterobisligation where one of the two sites binds the metal noncovalently), 173 which turns out to be mainly governed by electrostatics according to the QTAIM and IQA analysis. The same methods have been applied to the AgÁ Á ÁAg 174,175 and AuÁ Á ÁAu 176 interactions, revealing significant cooperative effects in the AuÁ Á ÁAu bonds. Similarly, the nature of the metal-carbene bonds has been examined in the cyclopropeny-lideneÁ Á ÁMX 2 and imidazol-2-ylideneÁ Á ÁMBr 2 complexes in which M = Be, Mg, Zn and X = Br, H. 177 Curiously, the results show that Be forms the strongest M-C bonds followed by Mg and Zn while the H atoms bound to the metal centers hinder the M-C bond in comparison with the electron-withdrawing Br atoms.…”

Wave function analyses of scandium-doped aluminium clusters, AlnSc (n= 1–24), and their CO2fixation abilities

“…These approaches have been successfully exploited in a wide variety of chemical bonding scenarios [41][42][43][44][45][46] including metallic interactions. 12,[47][48][49][50][51][52][53][54] Because of their above-mentioned favourable adsorption properties, we also investigated the interaction of these clusters with CO 2 as a potential relevant application of these systems. Our results reveal novel insights about the investigated nanoclusters, for instance, (i) the role of delocalised electrons in the cooperative effects observed in the formation of these complexes, (ii) the nature of the interaction of the Al 13 superatom with Al and Sc, (iii) how the scandium atoms modify the electronic and structural properties of Al clusters and (iv) how Al n Sc complexes activate the CO 2 molecule fostering further reactivity.…”