Search results for "Tetrahydrofuran"
showing 10 items of 284 documents
The Crystal Structure of the THF Adduct of Monolithioferrocene
2015
Single crystals of [Fe(η5-C5H4)(η5-C5H5)]2Li2(thf)4 (1) were obtained from a tetrahydrofuran solution containing monolithioferrocene. The title compound crystallizes in the monoclinic space group P21 with a = 9.6589(5) A, b = 17.4285(9) A, c = 30.3116(15) A, β = 91.911(2)° and V = 5099.8(5) A3 with three independent molecules of 1. All individual molecules feature a non- symmetric almost planar Li2C2 four-membered ring with two shorter (2.118–2.215 A) and two longer Li–C distances (2.257–2.309 A). The lithium cations are each coordinated by two carbanionic atoms of two ferrocenyl substituents and two tetrahydrofuran molecules in a distorted tetrahedral fashion. All ferrocenyl moieties displ…
The Iron Hydrido Complex [FeH(dppe)2]+: Solution and Solid-State Reactivity with Dinitrogen
2006
The blue compound [FeH(dppe)2]BPh4 (1) (dppe = 1,2-bis(diphenylphosphino)ethane) is investigated by optical absorption, vibrational, NMR and Mossbauer spectroscopy as well as magnetic susceptibility measurements. In the solid state, 1 is found to be paramagnetic (S=1) whereas in tetrahydrofuran (thf) solution it is diamagnetic. Importantly, 1 reacts with dinitrogen in thf solution and in the solid state to give the yellow and green dinitrogen complexes 2a and 2b, respectively, both of which have the formula [FeH(N2)(dppe)2]BPh4. Apart from their colour and optical spectroscopic properties, the dinitrogen compounds 2a and 2b also differ in their magnetic, Mossbauer and vibrational properties…
2-Tetrahydrofurfuroxo-vanadium-(III) and -(IV) complexes. Synthesis, structures and reactivities of [V2Mg2(μ3,δ2-thffo)2(μ,δ2-thffo)4Cl4]· 2CH2Cl2 an…
1997
Vanadium complexes of 2-tetrahydrofurfuroxide (2-tetrahydrofurylmethoxide) (thffo) with the metal in oxidation state III and IV have been prepared and characterized. The reaction of [VCl3(thf)3] with 1.5 equivalents of [Mg(thffo)2] in tetrahydrofuran (thf) or CH2Cl2 led to the formation of [V2Mg2(µ3,η2-thffo)2(µ,η2-thffo)4Cl4]· 2CH2Cl21. Its structure consists of centrosymmetric tetranuclear molecules and CH2Cl2 of crystallization. Two Mg and two V atoms have distorted octahedral geometry and form a nearly regular Mg2V2 rhombus. The V · · · V distance is 3.266(2) A. The reaction of [VOCl2(thf)2] with Na(thffo) in thf yielded [V2(µ,η2-thffo)2Cl2O2] 2. Two VOCl units are linked by alkoxide ox…
Solvent-dependent formation of Os(0) complexes by electrochemical reduction of [Os(CO)(2,2'-bipyridine)(L)Cl2]; L = Cl(-), PrCN.
2014
Cyclic voltammetry and ultraviolet-visible/infrared (UV-vis/IR) spectroelectrochemistry were used to study the cathodic electrochemical behavior of the osmium complexes mer-[Os(III)(CO) (bpy)Cl3] (bpy = 2,2'-bipyridine) and trans(Cl)-[Os(II)(CO) (PrCN)(bpy)Cl2] at variable temperature in different solvents (tetrahydrofuran (THF), butyronitrile (PrCN), acetonitrile (MeCN)) and electrolytes (Bu4NPF6, Bu4NCl). The precursors can be reduced to mer-[Os(II)(CO) (bpy(•-))Cl3](2-) and trans(Cl)-[Os(II)(CO)(PrCN) (bpy(•-))Cl2](-), respectively, which react rapidly at room temperature, losing the chloride ligands and forming Os(0) species. mer-[Os(III)(CO) (bpy)Cl3] is reduced in THF to give ultimate…
Stereospecific Polymerization of Isoprene with Nd(BH4)3(THF)3/MgBu2 as Catalyst
2004
The neodymium trisborohydride Nd(BH 4 ) 3 - (THF) 3 (THF = tetrahydrofuran) has been used as a catalyst precursor for isoprene polymerization for the first time. Associated to an excess of Al(Et) 3 , the resulting catalyst is moderately active, giving a mixture of cis- and trans- polymer. Addition of a stoichiometric amount of MgBu 2 to Nd(BH 4 ) 3 (THF) 3 affords a stereospecific catalyst providing trans-1,4-polyisoprene, more than 96% regular. That dual component Nd/Mg system also shows a better efficiency and good control of the molecular weights. A molecular structure is tentatively attributed to a bimetallic active species, based on 1 H NMR experiments.
New complexes of nickel and nickel/cobalt with tetrahydrofuran-2,3,4,5-tetracarboxylic acid, THF(COOH)4. Crystal structures of Ni[THF(COOH)2(COOH)2](…
1993
Abstract The reaction of NiCl2·6H2O with tetrahydrofuran-2,3,4,5-tetracarboxylic acid, THF(COOH)4, partially deprotonated by Na2CO3 (1 : 1 metal/ligand molar ratio), yielded Ni[THF(COOH)2(COO)2](H2O)3 (1). The molecular structure of 1 was determined by X-ray diffraction on the monocrystal. The structure consists of a mononuclear neutral unit with the nickel atom coordinated by a [THF(COOH)2(COO)2]2− ligand, which acts as a tridentate ligand, and three water molecules. Direct interaction of NiCl2·6H2O and CoCl2·6H2O (1 : 1 molar ratio) with THF(COOH)4 previously deprotonated by Na2CO3 (1 : 1 metal/ligand molar ratio) gave, by slow evaporation of the solution obtained, green crystals of the n…
CF3 Substitution of [Cu(P^P)(bpy)][PF6 ] Complexes: Effects on Photophysical Properties and Light-Emitting Electrochemical Cell Performance
2018
Herein, [Cu(P^P)(N^N)][PF6 ] complexes (P^P=bis[2-(diphenylphosphino)phenyl]ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos); N^N=CF3 -substituted 2,2'-bipyridines (6,6'-(CF3 )2 bpy, 6-CF3 bpy, 5,5'-(CF3 )2 bpy, 4,4'-(CF3 )2 bpy, 6,6'-Me2 -4,4'-(CF3 )2 bpy)) are reported. The effects of CF3 substitution on their structure as well as their electrochemical and photophysical properties are also presented. The HOMO-LUMO gap was tuned by the N^N ligand; the largest redshift in the metal-to-ligand charge transfer (MLCT) band was for [Cu(P^P){5,5'-(CF3 )2 bpy}][PF6 ]. In solution, the compounds are weak yellow to red emitters. The emission properties depend on the substitu…
The effect of THF and the chelating modifier DTHFP on the copolymerisation of β-myrcene and styrene: kinetics, microstructures, morphologies, and mec…
2022
The statistical anionic copolymerisation of the biobased monomer β-myrcene with styrene in cyclohexane was investigated via in situ near-infrared (NIR) spectroscopy, focusing on the influence of the modifiers (i.e., Lewis bases) tetrahydrofuran (THF) and 2,2-di(2-tetrahydrofuryl)propane (DTHFP) on the reactivity ratios. With increasing [modifier]/[Li] ratio, the reactivity ratios in the system myrcene/styrene are adjustable from rS ≪ rMyrvia rS ≈ rMyr to rS ≫ rMyr. The bidentate modifier DTHFP affects the reactivity ratios much more than THF: minute amounts only (0.35 equivalent relative to Li) are required to randomize the copolymer, and one equivalent to invert the reactivity ratios. Usin…
Gradient high-performance liquid chromatography of statistical and block copolymers of styrene and t-butyl methacrylate
1989
Copolymers of styrene (S) and tert-butyl methacrylate (TBMA) containing 24–92 mass % of the latter monomer were investigated using a silica column with isooctane/tetrahydrofuran (THF) gradients and on a phenyl bonded-phase column by methanol (MeOH)/THF gradients using UV detection. In both cases, retention decreased with increasing TBMA content of the sample. This is in contrast to the behavior of copolymers of S and methyl methacrylate (MMA) whose retention in gradient elution on silica columns increases with MMA content due to the polarity of this unit. The inversion of elution order is a result of the bulky TBMA residues shielding the polar groups of the ester units. For copolymers of va…
Tetrahydrofuran: More than a “Randomizer” in the Living Anionic Copolymerization of Styrene and Isoprene: Kinetics, Microstructures, Morphologies, an…
2020
The statistical anionic copolymerization of isoprene (I) and styrene (S) is commonly used to synthesize tapered block copolymers, enabling control of the phase behavior by adjusting the order–disor...