Reactions and Thermochemistry of Small Cluster Ions:  Fe(CS₂)_n⁺(n= 1, 2)

Abstract

Thermal reactions of Fe(CS2) n + (n = 1, 2) with a series of ligand molecules, L, have been studied by using a selected ion flow tube. Primary reactions observed include ligand association, ligand switching, and charge transfer. Fe(CS2)+ favors association while Fe(CS2)2 + undergoes mainly switching reactions. The bond dissociation energy D°(Fe+−CS2) = 39.6 ± 2.5 kcal/mol was determined by the measurement of forward and backward ligand switching rate constants. This value was verified by the observation of the onset of switching for a series of reactions Fe(CS2)+ + L → FeL+ + CS2 as a function of D°(Fe+−L). Consecutive reactions in the flow tube tend to produce end products having a maximum coordination number of four, e.g., Fe(CS2)L3 + and Fe(L)4 +, where L is a monodentate ligand such as NH3 or Fe(L)2 + with polydentate ligands such as C6H6. The interactions of Fe(CS2)+ and Fe(CS2)2 + with Xe were studied using a guided ion beam apparatus. Collision-induced dissociation (CID) thresholds gave bond dissociation energies of D o°(Fe+−CS2) = 39.7 ± 1.1 kcal/mol in excellent agreement with the SIFT result and D o°(CS2Fe+−CS2) = 45.0 ± 1.4 kcal/mol. Additional higher energy products in the Fe(CS2)+ system observed are FeXe+ and FeS+.

Reactivity of Metal Clusters

“…Cluster ions in gas phase largely undergo studies of metastability, photoexcited dissociation, collision-induced dissociation (CID), and cluster–molecule reactions. , Among them, investigations into metal cluster reactivity have been generally accomplished by analyzing the ions produced through supersonic coexpansion and/or in fast flow of clusters and reactants. − Along with the development of various commercial mass spectrometers, the customized reaction cells, flowing after-glow tubes, ion traps, and gas-flow reactors have provided a wealth of information on the reactivity of metal clusters. − In particular, advances in the technology of ion traps and flow-tube reactors have dominated the investigations of cluster chemistry during the past decades. ,,, Among others, there are also alternative methods of thermalizing clusters other than the flow tube or ion trap. − We hereby summarize a few customized aparatuses that have been used to study cluster reactivity of metals in the gas phase.…”

Cationic Noncovalent Interactions: Energetics and Periodic Trends

“…BDEs to CO 2 have been measured for a wider array of metal cations: Na + ( x = 1–4), , Mg + ( x = 1–3), , Fe + ( x = 1–5), ,, K + , Cs + , and Mo + ( x = 1) . CS 2 has been measured for only transition metals: V + and Mo + ( x = 1), and Fe + ( x = 1 and 2) . Both TCID (C) ,,, and high pressure temperature-dependent equilibria (H) ,,− have been used to measure BDEs for the simplest alkanes, CH 4 and C 2 H 6 , with several metal cations.…”

“…136 CS 2 has been measured for only transition metals: V + and Mo + (x = 1), 146 and Fe + (x = 1 and 2). 200 Both TCID (C) 82,161,201,202 and high pressure temperature-dependent equilibria (H) 91,128,203−206 have been used to measure BDEs for the simplest alkanes, CH 4 and C 2 H 6 , with several metal cations. Values for Fe + and Co + measured using both methods agree reasonably well and when they do not (as 41,81,107,118,166,167,196,209,212,218,219,225,226,260 E = single temperature equilibrium, 12,15,16,113,114,116,117,[187][188][189]228 H = high-pressure temperature-dependent equilibrium, 111,115,186,221,223 and P = photodissociation.…”

The electronic states of Fe2S2−/0/+/2+

“…8 Differently charged FeS species have been studied in detail. [9][10][11][12][13][14][15][16][17][18][19][20][21] Further, FeS n ϩ clusters have been generated 13,19,[22][23][24][25] and dissociation energies determined. 13,19 An experimental and computational study on FeS 2 Ϫ/0/ϩ considered, among others, redox properties.…”