Elucidating the Structures of Intermediate Fragments during Stepwise Dissociation of Monolayer‐Protected Silver Clusters

Abstract

Fragmentation dynamics of ligated coinage metal clusters reflects their structural and bonding properties. So far methodological challenges limited probing structures of the fragments. Herein, we resolve the geometric structures of the primary fragments of [Ag29L12]3−, i.e. [Ag24L9]2−, [Ag19L6]− and [Ag5L3]− (L is 1,3‐benzene dithiolate). For this, we used trapped ion mobility mass spectrometry to determine collision cross sections of the fragments and compared them to structures calculated by density functional theory. We also report that following two sequential [Ag5L3]− elimination steps, further dissociation of [Ag19L6]− also involves a new channel of Ag2 loss and Ag−S and C−S bond cleavages. This reflects a competition between retaining the electronic stability of 8 e− superatom cluster cores and increasing steric strain of ligands and staples. These results are also of potential interest for future soft‐landing deposition studies aimed at probing catalytic behavior of Ag clusters on supports.

Tailoring Vacancy Defects in Isolated Atomically Precise Silver Clusters through Mercury-Doped Intermediates

“…Typical CID spectra at varying normalized collision energies (NCE) are presented in Figure S6. Following the removal of the Hg atom, the same fragmentation channel as observed for the reference [Ag 29 (BDT) 12 ] 3– cluster, , i.e., [Ag 5 (BDT) 3 ] − loss, was seen (Figure S6). The corresponding NCE-resolved fragmentation curves are presented in Figure A.…”

“…27 The fragment ion was produced by increasing the ion transmission voltages before the TIMS separation (Figure S8) following previously established methodologies. 26,28 Respective TIMS mobilograms of parent [Ag 28 Hg(BDT) 12 ] 2− and fragment [Ag 28 (BDT) 12 ] 2− are in Figure 2B. The experimental CCS obtained from TIMS ( TIMS CCS N2 ) of [Ag 28 Hg(BDT) 12 ] 2− and [Ag 28 (BDT) 12 ] 2− were 446.4 Å 2 and 441.0 Å 2 , respectively.…”

“…29 In our previous report, we discussed the reliability of the calculation method by comparison of the experimental CCS value (476 Å 2 ) of [Ag 29 (BDT) 12 ] 3− to the theoretical CCS based on its crystal structure. 26 Note that the lower CCS of [Ag 28 Hg(BDT) 12 ] 2− compared to that of parent [Ag 29 (BDT) 12 ] 3− cluster is primarily associated with the change in its charge state and not the geometrical structure as the charge-induced dipole interactions also effect the CCS. 30 TM CCS N2 of [Ag 28 Hg(BDT) 12 ] 2− isomers were ∼441.9−442.9 Å 2 in agreement with the experimental value of 446.4 Å 2 .…”

“…To explore the structural changes, we performed TIMS studies on isolated [Ag 28 Hg­(BDT) 12 ] 2– and [Ag 28 (BDT) 12 ] 2– clusters to obtain collision cross sections (CCS) of the ions in N 2 gas and hence information on the structure . The fragment ion was produced by increasing the ion transmission voltages before the TIMS separation (Figure S8) following previously established methodologies. , Respective TIMS mobilograms of parent [Ag 28 Hg­(BDT) 12 ] 2– and fragment [Ag 28 (BDT) 12 ] 2– are in Figure B. The experimental CCS obtained from TIMS ( TIMS CCS N2 ) of [Ag 28 Hg­(BDT) 12 ] 2– and [Ag 28 (BDT) 12 ] 2– were 446.4 Å 2 and 441.0 Å 2 , respectively.…”

“…CCSs of these calculated structures ( TM CCS N2 ) were modeled using the trajectory method (TM) as implemented in IMoS 1.09 . In our previous report, we discussed the reliability of the calculation method by comparison of the experimental CCS value (476 Å 2 ) of [Ag 29 (BDT) 12 ] 3– to the theoretical CCS based on its crystal structure . Note that the lower CCS of [Ag 28 Hg­(BDT) 12 ] 2– compared to that of parent [Ag 29 (BDT) 12 ] 3– cluster is primarily associated with the change in its charge state and not the geometrical structure as the charge-induced dipole interactions also effect the CCS …”