X-ray absorption fine structure spectroscopic study of (NH[subscript 4])[subscript 2]ReF[subscript 6]
Abstract not provided
Polneau, Frederic↗
Engineering topics
Mariappan Balasekaran, Samundeeswari
Publications and source records attributed to Mariappan Balasekaran, Samundeeswari.
Uncovering Multiple Metal-Metal Bonding in a Tetranuclear Fluoride Rhenium Cluster or the Curious Case of {[Ni(H 2 O) 6 ](NH 4 ) 4 }[Re 4 F 18 ]·4H 2 O
The compound {[Ni(H 2 O) 6 ](NH 4 ) 4 }[Re 4 F 18 ]·4H 2 O (1) has been isolated and characterized by single-crystal X-ray diffraction, Raman spectroscopy and computational methods. The compound 1 crystallizes in the triclinic space group P 1 (a = 6.6620(9) Å, b = 9.7121(13) Å, c = 11.2007(15) Å, α = 67.644(2)°, β = 83.827(2)°, γ = 84.366(2)°). In 1, the [Re 4 F 18 ] 6– anion is composed of four Re(III) atoms bridged by two µ-bridging fluorine atoms and two di-µ-bridging fluorine atoms. Furthermore, in [Re 4 F 18 ] 6– , the shortest Re–Re distance (i.e., 2.3631(6) Å) is characteristic of the presence of a Re=Re double bond; the Re–F distances range from 1.854(6) to 2.008(5) Å. Theoretical calculations confirm the presence of a weak Re=Re double bond; the Mayer–Mulliken bond order of the doubly bridged Re atoms is 1.8097 and the natural localized molecular orbital bond order is 1.8751. The Raman spectrum of 1 has been measured and shows a series of bands in the region 167–1449 cm –1 that have been attributed to Re–F and Ni–O stretches, Re 4 F 18 ring breathing and NH 4 + bending and libration modes.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
An unexpected rhenium(IV)–rhenium(VII) salt: [Co(NH 3 ) 6 ] 3 [Re VII O 4 ][Re IV F 6 ] 4 ·6H 2 O
The title hydrated salt, tris[hexaamminecobalt(III)] tetraoxidorhenate(VII) tetrakis[hexafluoridorhenate(IV)] hexahydrate, arose unexpectedly due to possible contamination of the K 2 ReF 6 starting material with KReO 4 . It consists of octahedral [Co(NH 3 ) 6 ] 3+ cation (Co1 site symmetry 1), tetrahedral [Re VII O 4 ] − anions (Re site symmetry 1) and octahedral [Re IV F 6 ] 2− anions (Re site symmetries 1and \overline{3}). The [ReF 6 ] 2− octahedral anions (mean Re—F = 1.834 Å), [Co(NH 3 ) 6 ] 3+ octahedral cations (mean Co—N = 1.962 Å), and the [ReO 4 ] − tetrahedral anion (mean Re—O = 1.719 Å) are slightly distorted. A network of N—H...F hydrogen bonds consolidates the structure. The crystal studied was refined as a two-component twin.
Louis–Jean, James (ORCID:0000000277110967)↗
Syntheses, Raman spectroscopy and crystal structures of alkali hexafluoridorhenates(IV) revisited
The A 2 [ReF 6 ] (A = K, Rb and Cs) salts are isotypic and crystallize in the trigonal space group type P$\bar{3}$m1, adopting the K 2 [GeF 6 ] structure type. Common to all A 2 [ReF 6 ] structures are slightly distorted octahedral [ReF 6 ] 2- anions with an average Re—F bond length of 1.951 (8) Å. In these salts, symmetry lowering on the local [ReF 6 ] 2- anions from O h (free anion) to D 3d (solid-state structure) occur. The distortions of the [ReF 6 ] 2- anions, as observed in their Raman spectra, are correlated to the size of the counter-cations.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Octafluorodirhenate(III) Revisited: Solid-State Preparation, Characterization, and Multiconfigurational Quantum Chemical Calculations
A simple method for the high-yield preparation of (NH 4 ) 2 [Re 2 F 8 ]· 2H 2 O has been developed that involves the reaction of (n-Bu 4 N)2[Re 2 Cl 8 ] with molten ammonium bifluoride (NH 4 HF 2 ). Using this method, the new salt [NH 4 ] 2 [Re 2 F 8 ]·2H 2 O was prepared in ~90% yield. The product was characterized in solution by ultraviolet-visible light (UV-vis) and 19 F nuclear magnetic resonance (19F NMR) spectroscopies and in the solid-state by elemental analysis, powder X-ray diffraction (XRD), and infrared (IR) spectroscopy. Multiconfigurational CASSCF/CASPT2 quantum chemical calculations were performed to investigate the molecular and electronic structure, as well as the electronic absorption spectrum of the [Re 2 F 8 ] 2- anion. The metal-metal bonding in the Re 2 6+ unit was quantified in terms of effective bond order (EBO) and compared to that of its [Re 2 Cl 8 ] 2- and [Re 2 Br 8 ] 2- analogues.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗