Solvothermal Approach to the Synthesis of Triangular Re(III) Iodide and Bromide Cluster Complexes

Abstract: Crystalline Re3I9 (1) is formed in a quantitative yield upon the hydrothermal reaction of NaReO4 with concentrated HI at 200°C. The reaction of Re3I9 with HBr at 200°C results in complete replacement of iodide ligands with bromide ligands with retention of the cluster core. The addition of pyridine to the reaction mixture leads to crystallization of the pyridinium salt (PyH)2[Re3Br11(H2O)] · 4H2O (2). In the presence of phosphoric acid, (PyH)2[Re3Br9(PO4H)]·H2O (3) and (Et4N)2[Re3Br9(PO4H)]·2H2O (4) were isolated. The crystal structures of the compounds 2–4 were determined by single crystal X-ray diffraction. Complexes 1 and 4 were characterized by powder X-ray diffraction. The Re/halogen ratio for compounds 1–4 was determined by energy dispersive spectroscopy. Elemental analysis and 31P NMR spectroscopy data were obtained for compound 4, and vibrational spectra were measured for 1 (far-IR range) and 4 (near-IR range). The data for thermal stability in inert atmosphere were obtained for 1

Thiocyanate Coordination to the {Ta<inf>6</inf>I<inf>12</inf>}²⁺ Cluster. Preparation and Crystal Structure of [K(Dibenzo-24-Crown-8)(CH<inf>3</inf>COCH<inf>3</inf>)]<inf>2</inf>(Ph<inf>4</inf>P)<inf>2</inf>[Ta<inf>6</inf>I<inf>12</inf>(NCS)<inf>6</inf>]

© 2020, Pleiades Publishing, Ltd. The reaction of Ta6I14 with KNCS in acetonitrile in the presence of 24-dibenzo-crown-8 leads to dissolution of the tantalum iodide cluster to form the [Ta6I12(NCS)6]4− complex. By evaporation of the solution with the subsequent treatment of the precipitate with acetone and PPh4Br, dark green single crystals of the composition [K(C24H32O8)(CH3COCH3)]2(Ph4P)2[Ta6I12(NCS)6] CH3COCH3(1) are obtained with a yield of 29%. The product is characterized by elemental analysis, IR, and mass spectra. The crystal structure is determined by the X-ray diffraction analysis

Phosphorescent complexes of {Mo<inf>6</inf>I<inf>8</inf>}⁴⁺with triazolates: [2+3] cycloaddition of alkynes to [Mo<inf>6</inf>I<inf>8</inf>(N<inf>3</inf>)<inf>6</inf>]^2-

© The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. (Bu4N)2[Mo6I8(N3)6], prepared in a clean high-yield reaction from (Bu4N)2[Mo6I8(CH3COO)6] and Me3SiN3, undergoes [3+2] cycloaddition with CH3O(O)CC(O)OCH3 with the formation of a novel hexakis(triazolate) complex, (Bu4N)2[Mo6I8(N3C2(COOCH3)2)6] with symmetrically coordinated 4,5-di(carbmethoxy)triazol-2-yl ligands. The product was characterized by X-ray analysis, NMR, IR and ESI-mass spectrometry. It undergoes a quasi reversible oxidation in CH3CN at E1/2 = 1.36 V (vs. Ag/AgCl) and is red-light emissive upon UV photoexcitation. Reaction with methylpropiolate also yields a corresponding hexakis(triazolate) complex, [Mo6I8(N3C2H(COOCH3))6]2-, which exists as a 1:1 mixture of two isomers. Alkynes that lacking strongly electron-withdrawing substituents fail to undergo the cycloaddition reaction. This journal i

PROPIOLATE CLUSTER COMPLEXES (Bu<inf>4</inf>N)<inf>2</inf>[Mo<inf>6</inf> X <inf>8</inf>(OOC–C≡CH)<inf>6</inf>] (X = Br, I)

Abstract: Two new cluster complexes (Bu4N)2[Mo6X8(OOC–C≡CH)6] (1) (X = Br) and (2) (X = I) are synthesized by the reaction of (Bu4N)2[Mo6X8(OOCCH3)6] (X = Br, I) with HOOC–C≡CH propiolic acid, their crystal structures are determined, and the luminescent properties are studied for powder samples at different temperatures. According to X-ray crystallographic data, molybdenum atoms are monodentately coordinated by oxygen atoms of the carboxyl group at Mo–O distances of 2.108(2)-2.121(16) Å. The propiolate complexes are characterized by electrospray mass spectrometry, 1Н and 13С NMR, elemental analysis, and IR spectroscopy. [Figure not available: see fulltext.

Reversible dimerization of anion radicals of carbonyl compounds and the electrosynthesis of pinacols. The case of 9-fluorenone

International audienceReversible dimerization of the anion radicals of carbonyl compounds was studied by cyclic voltammetry, chronoamperometry, electrolysis, digital simulation and quantum chemical calculations using electroreduction of 9-fluorenone in DMF/0.1 M Bu4NClO4 as an example. The experimental data confirmed that this reaction is thermodynamically unfavorable as it was predicted by DFT calculations. In contrast with some other anion radicals, neither ion pairing of 9-fluorenone anion radicals with lithium cation nor their hydrogen bonding with water shifts the dimerization equilibrium to the dimeric product. Reversibility of the dimerization decreases in the presence of phenol due to the protonation of the dimeric dianion and to the irreversibility of dimerization of the anion radical – phenol complexes. The contribution of these two pathways to general hydrodimerization process is discussed. © 2020 Elsevier Lt