On the Stability of IrCl₆^3- and Other Triply Charged Anions:  Solvent Stabilization versus Ionic Fragmentation and Electron Detachment for the IrCl₆^3-·(H₂O)_n n = 0−10 Microsolvated Clusters

Abstract

The intrinsic gas-phase stability of the IrCl(6)(3-) trianion and its microsolvated clusters, IrCl(6)(3-).(H(2)O)(n) n = 1-10, have been investigated using density functional theory (DFT) calculations. Although IrCl(6)(3-) is known to exist as a stable complex ion in bulk solutions, our calculations indicate that the bare trianion is metastable with respect to decay via both electron detachment and ionic fragmentation. To estimate the lifetime of IrCl(6)(3-), we have computed the electron tunneling probability using an adaption of the Wentzel-Kramer-Brillouin theory and predict that the trianion will decay spontaneously via electron tunneling on a time scale of 2.4 x 10(-13) s. The global minimum structure for IrCl(6)(3-).H(2)O was found to contain a bifurcated hydrogen bond, whereas for IrCl(6)(3-).(H(2)O)(2), two low energy minima were identified; one involving two bifurcated water-ion hydrogen bonds and a second combining a bifurcated hydrogen bond with a water-water hydrogen bond. Clusters based on each of these structural motifs were obtained for all of the n = 3-10 systems, and the effect of solvation on the possible decay pathways was explored. The calculations reveal that solvation stabilizes IrCl(6)(3-) with respect to both electron detachment decay and ionic fragmentation, with the magnitude of the repulsive Coulomb barrier for ionic fragmentation increasing smoothly with sequential solvation. This study is the first to compare the propensity for electron detachment versus ionic fragmentation decay for a sequentially solvated triply charged anion.

Solvent evaporation versus proton transfer in nucleobase–Pt(CN)4,62− dianion clusters: a collisional excitation and electronic laser photodissociation spectroscopy study

“…It is notable that the proton-transfer reaction shuts down for the larger clusters, indicating that the barrier height for this reactive process increases with solvation. 22 ÁUr decay with similar fragmentation energies (E 1/2 values of 3.8, 3.8 and 3.9% CID energy, respectively), Pt(CN) 6…”

“…For Pt(CN) 4 2À ÁCy, solvent evaporation is the major fragmentation process, a difference that can be attributed to the relatively low gas-phase acidity of Cy. 21 The observation that the Pt(CN) , 20 so that the solvent evaporation barrier will be higher for the Pt(CN) 4 2À ÁM clusters, 22 ÁM is mirrored by the corresponding trimer clusters. The major fragmentation channel corresponds to loss of one nucleobase (4a), with loss of two nucleobase units occurring at higher collision energies (4c).…”

Stabilization of Excess Charge in Isolated Adenosine 5‘-Triphosphate and Adenosine 5‘-Diphosphate Multiply and Singly Charged Anions

“…This mirrors the known stabilization of multiply charged anions with respect to both ionic fragmentation and electron detachment via sequential solvation with water molecules. 6,[14][15][16][17]51,52 Nonetheless, the intrinsic stability of the dianions studied will also be affected by the extent of dielectric screening that exists between the excess charges. This effect is implicitly included within the third term of eq 3, where any dielectric screening acts to reduce the overall intramolecular Coulomb repulsion.…”

One-pot synthesis of Au-based nanocrystals via a platinum group metal anion controlled growth strategy in citrate medium

“…The purpose of reducing surface energy cannot be achieved without the addition of other reaction precursors or with the addition of trianion IrCl 6 3À which is known to be a stable complex anion in a condensed phase environment. [25][26][27] Therefore, Au NWs spontaneously agglomerate into large, lower surface energy, irregular Au NPs with reduced surface energy at room temperature (Fig. 5d).…”