Hydride-Containing Eight-Electron Pt/Ag Superatoms: Structure, Bonding, and Multi-NMR Studies

Abstract

Recent reports on hydride-doped noble metal nanoclusters strongly suggest that the encapsulated hydride is a part of the superatom core, but no accurate location of the hydride could be experimentally proved, so far. We report herein a hydride-doped eight-electron platinum/silver alloy nanocluster in which the position of four-coordinated hydride was determined by neutron diffraction for the first time. X-ray structures of [PtHAg19(dtp/desp)12] (dtp = S2P­(O n Pr)2, 1; dsep = Se2P­(O i Pr)2, 2) describe a central platinum hydride (PtH) unit encapsulated within a distorted Ag12 icosahedron, the resulting (PtH)@Ag12 core being stabilized by an outer sphere made up of 7 capping silver atoms and 12 dichalcogenolates. Solid-state structures of 1 and 2 differ somewhat in the spatial configuration of their outer spheres, resulting in overall different symmetries, C 1 and C 3, respectively. Whereas the multi-NMR spectra of 2 in solution at 173 K reveal that the structure of C 3 symmetry is the predominant one, 1H and 195Pt NMR spectra of 1 at the same temperature disclose the presence of isomers of both C 1 and C 3 symmetry. DFT calculations found both isomers to be very close in energy, supporting the fact that they co-exist in solution. They also show that the [PtH@Ag12]5+ kernel can be viewed as a closed-shell superatomic core, the μ4-hydride electron contributing to its eight-electron count. On the other hand, the 1s­(H) orbital contributes only moderately to the superatomic orbitals, being mainly involved in the building of a Pt–H bonding electron pair with the 5dz 2(Pt) orbital.

Surface modifications of eight-electron palladium silver superatomic alloys

“…S7). The possibility of partial replacement of ligands cannot be excluded, however we have never encountered the partial replacement when we intend to produce dsep protected NCs from their dtp siblings via LE method [20][21][22][28][29][30][31][32][33][34] . In particular, most of the cases these reactions are associated with alteration of the metallic cores [20][21][22][28][29][30][31][32][33][34] .…”

“…The possibility of partial replacement of ligands cannot be excluded, however we have never encountered the partial replacement when we intend to produce dsep protected NCs from their dtp siblings via LE method [20][21][22][28][29][30][31][32][33][34] . In particular, most of the cases these reactions are associated with alteration of the metallic cores [20][21][22][28][29][30][31][32][33][34] . The change in metallic core is certainly a reason for the distinct color change, however we believe the change in the ligand environment plays a major role for the immediate color change.…”

“…DFT calculations were carried out on simplified model clusters with the Gaussian 16 package 54 . The considered ligand simplifications allow to save a huge amount of CPU time and its validity has been proven in many occasions [20][21][22]36,41,43 . The BP86 functional 55,56 was used together with the general triple-ζ polarized Def2-TZVP basis set from EMSL Basis Set Exchange Library 57,58 .…”

“…In this regard, the more common protecting ligands employed to isolate different NCs are thiols, phosphines, alkynes, hydrides or their combinations 1,[10][11][12][13][14][15][16] . In contrast, structurally precise Au and Ag clusters co-protected by selenols are much rarer, with approximately twenty reported examples [17][18][19][20][21][22] . In order to illuminate the effects of surface functionalization of nanoparticles, recent reports have demonstrated the fabrication of several stable functional nanomaterials by using selenolates in the place of thiolates as protecting ligands.…”

Surface Modifications of eight-electron Pd/Ag Superatomic Alloys

“…1,10−16 In contrast, structurally precise Au and Ag clusters co-protected by selenols are much rarer, with approximately twenty reported examples. [17][18][19][20][21][22] In order to illuminate the effects of surface functionalization of nanoparticles, recent reports have demonstrated the fabrication of novel stable functional nanomaterials by using selenolates in the place of thiolates as protecting ligands. Unlike in thiolate-protected NCs, true structural isomerism, which is an interesting feature for ne tuning many properties, has not been reported so far for selenolate-protected species.…”