12082-08-5Relevant academic research and scientific papers
ELECTRON TRANSFER FROM AROMATIC HYDROCARBONS AND THEIR pi -COMPLEXES WITH METALS. COMPARISON OF THE STANDARD OXIDATION POTENTIALS AND VERTICAL IONIZATION POTENTIALS.
Howell,Goncalves,Amatore,Klasinc,Wightman,Kochi
, p. 3968 - 3976 (1984)
The energetics of electron transfer from an extensive series of alkyl-substituted benzenes are measured both in solution and in the gas phase. The standard oxidation potentials E//A//r degree stem from the reversible cyclic voltammograms (CV) in trifluoroacetic acid using the recently developed microvoltammetric electrodes. These values show an excellent correlation with the vertical ionization potentials I//p of the same aromatic hydrocarbons in the gas phase. Thermochemical analysis indicates that the slope of less than unity for the correlation arises mainly from solvation differences, particularly in the highly substituted polyalkylbenzenes.
NAPHTHALENE COMPLEXES. V. ARENE EXCHANGE REACTIONS IN NAPHTHALENECHROMIUM COMPLEXES
Kuendig, E. P.,Perret, C.,Spichiger, S.,Bernardinelli, G.
, p. 183 - 200 (1985)
Di-η6-naphthalenechromium(0) (1) reacts at 150 deg C with benzene to yield (η6-naphthalene)(η6-benzene)chromium(0) (3) in 76percent yield.In the presence of THF, 1 undergoes Lewis base catalyzed arene exchange at 80 deg C.Reactions of 1 with substituted arenes yield the mixed sandwich complexes 4 and 6-10 (arene=1,4-C6H4Me2, 1,3,5-C6H3Me3, C6Me6, 1,4-C6H4(OMe)2, 1,4-C6H4F2 and 1,4-C10H6Me2).In all but one case (witih 1,4-dimethylnaphthalene) exchange of a single naphthalene ligand is observed.In marked contrast to the lability of 1, dimesitylenechromium(0) (5) is inert to arene diplacement in benzene up to 240 deg C.The molecular structure of 3 has been determined by X-ray crystallography.The crystal data are as follows: a 7.784(1), b 13.411(2), c 22.772(5) Angstroem, Z=8, space group Pbca.The structure was refined to a RW value of 0.043.The naphtahlene ligand in 3 is nearly planar and parallel to the approximately eclipsed benzne ring.Metal atom-ring distances are 1.631(9) and 1.611(4) Angstroem for naphthalene and benzene, respectively.Catalyzed and uncatalyzed naphtahlene exchanges in the sandwich complex are compared to the analogous reactions with the Cr(CO)3 complex 2.Naphthalene exchange in 2 in benzene is 1E3 to 1E4 times fastere than arene exchange in other arenetricarbonylchromium compounds.The mild conditions for Lewis base catalyzed naphthalene exchange make 2 a good precursor of other arenetricarbonylchromium compounds.Examples include the Cr(CO)3 complexes of styrene, benzocyclobutene, 1-ethoxybenzocyclobutene, 1,8-diemthoxy-9,10-dihydroanthracene and 1,4-dimethylnaphthalene.
Intramolecular vibrational relaxation in n-alkyl benzene chromium tricarbonyls: State selective production of chromium atoms
Hossenlopp, Jeanne M.,Samoriski, Brian,Rooney, Dan,Chaiken, J.
, p. 3331 - 3337 (1986)
We have measured one color multiphoton dissociation/ionization (MPD/MPI) spectra for a series of n-alkyl substituted arene chromium tricarbonyls (ACTs) .Our data indicate that intramolecular vibrational relaxation (IVR) rates for methyl, ethyl, and propyl ACTs increase relative to the benzene analog in the ratio of 3:6:34.In contrast, the net relaxation rates of the p-xylene (dimethyl) and mesitylene (trimethyl) analogs are two and three times faster than benzene, respectively.The behavior of these latter analogs probably also reflects differences in electronic structure relative to the benzene ACT.Taken with the results of experiments on other analogs and the independently obtained results on the uncomplexed arenes, we have found a strong correlation between the presence of low frequency vibrations and the rate of IVR.The rate of IVR determines the distribution of neutral chromium atoms formed by MPD of the n-alkyl ACTs.
Stereoselective synthesis and some reactions of β-(η6-arene)Cr(CO)3 complexes of podocarpic acid derivatives
Clark, George R.,Kuipers, Bianca,Metzler, Michael R.,Nguyen, Manh H.,Woodgate, Paul D.
, p. 225 - 247 (1997)
The stereoselective synthesis of a number of (η6-arene)tricarbonylchrorniurn(0) complexes derived from podocarpic acid has been achieved in good to excellent yield. The stereochemistry of complexes 36 and 37 was established by X-ray crystallography. Reactions of some of the deprotonated complexes with electrophiles were investigated.
UV Laser Photolysis of (η6-C6H6)Cr(CO)3: Time-Resolved Infrared Studies of Gas-Phase (η6-C6H6)Cr(CO)x (x = 2 and 1)
Wang, Wenhua,Jin, Pei,Liu, Yanwei,She, Yongbo,Fu, Ke-Jian
, p. 1278 - 1283 (1992)
The time-resolved infrared absorption spectra of the coordinatively unsaturated (η6-C6H6)Cr(CO)x (x = 2 and 1) species generated via UV laser photolysis of the gas-phase (η6-C6H6)Cr(CO)3 are presented and discussed.The photofragments produced upon 355- and 266-nm photolysis are identified. (η6-C6H6)Cr(CO)2 is the predominant product upon 355-nm photolysis, while both (η6-C6H6)Cr(CO)2 and (η6-C6H6)Cr(CO) are produced upon 266-nm photolysis with a ratio of (η6-C6H6)Cr(CO)2:(η6-C6H6)Cr(CO) of about 2:5.The rate constants for reactions of (η6-C6H6)Cr(CO)2 and (η6-C6H6)Cr(CO) with CO are measured and found to be (6.3 +/- 0.3) * 1012 and (1.4 +/- 0.2) * 1012 cm3 mol-1 s-1, respectively.The rate constant for reaction of (η6-C6H6)Cr(CO)2 with CO lies between the corresponding values for spin-allowed and spin-disallowed reactions of other coordinatively unsaturated metal carbonyl species with CO.
Investigating the reactivity of the (η6-C6H 5R)Cr(CO)2-(η2-C6H5R) [R = H, CH3, CF3] bond: A laser flash photolysis study with infrared detection
Bengali, Ashfaq A.,Grunbeck, Amy R.
, p. 5919 - 5924 (2005)
The (η6-C6H5R)Cr(CO) 2-(η2-C6H5R) complexes (R = H, CH3, CF3) are generated upon photolysis of (η6-C6H5R)Cr(CO)3 in the appropriate arene. The energetics and mechanism of the displacement of the η2-coordinated arene from the metal center by piperidine are studied using the technique of laser flash photolysis. The substitution reaction is tentatively assigned as proceeding through an Id mechanism, and the activation enthalpy of 11.5 ± 0.9 kcal/mol provides a lower limit for the strength of the (η6-C6H6)Cr(CO) 2-(η2-C6H6) bond. The substitution rate decreases as the metal center becomes more electron poor or the arene electron rich, suggesting that L→M σ donation is the primary bonding interaction between the (η6-C6H 5R)Cr(CO)2 fragment and the arene ligand. This reactivity is different from that of the Cr - (η2-alkene) bond, where it was found that increasing the electron density on the metal center decreased the rate of substitution of cyclooctene from the (η6-C 6H5R)Cr(CO)2-(η2-cyclooctene) complex by pyridine.
Protodeboronation of arylboronic acids and triarylboroxines in Bu2O/THF
Beckett, Michael A.,Gilmore, Robert J.,Idrees, Khalid
, p. 47 - 49 (1993)
The arylboron compounds Ph3B3N3Me3, Ar3B3O3, or ArB(OH)2 (Ar = Ph, p-BrC6H4, p-MeC6H4, m-NH2C6H4) react with in refluxing Bu2O/THF (9:1) to afford the η6-arene)tricarbonylchromium(0) complexes of the protodeboronated substrates in yie
Photochemical synthesis of arenetricarbonylchromium(0) complexes: scope and limitations
Kostermans, G. B. M.,Bobeldijk, M.,Kwakman, P. J.,Wolf, W. H. de,Bickelhaupt, F.
, p. 291 - 296 (1989)
Two photochemical methods for the preparation of arenetricarbonylchromium(0) complexes are described.The first involves irradiation of a solution of hexacarbonylchromium(0) and arene in THF at room temperature with a medium pressure mercury lamp.In the se
Dimeric boroles: Effective sources of monomeric boroles for heterocycle synthesis
Su, Xiaojun,Baker,Martin, Caleb D.
, p. 126 - 131 (2020)
Monomeric boroles have been gaining attention as reagents for the synthesis of heterocycles due to their ability to insert atoms into the BC4 ring in a single step. Although unique boron frameworks can be accessed via this methodology, the products feature aryl substitution on the carbon centers as steric bulk is required to preclude borole dimerization. This work demonstrates that insertion chemistry is possible with Diels-Alder dimeric boroles and that such reactivity is not exclusive to monomeric boroles with bulky groups. With 1-phenyl-2,3,4,5-tetramethylborole dimer, the formal 1,1-insertion of a nitrene and sulfur generate the six-membered aromatic 1,2-azaborine and 1,2-thiaborine, respectively. The isolation of the 1,2-thiaborine enabled the synthesis of an η6-chromium complex. Benzophenone and diphenylketene readily insert a CO unit to generate BOC5 seven-membered rings confirming dimeric boroles can serve as monomeric synthons in 1,2-insertion reactions. An epoxide did not furnish the anticipated eight-membered BOC6 ring, instead provided a bicyclic system with a BOC3 ring. The insertion chemistry was demonstrated with two other borole dimers featuring different substitution with diphenylketene as a substrate. This work elevates borole insertion chemistry to a new level to access products that do not require bulky substitution.
Tetracarbonyl Ferrate Derivatives of (η6-arene)Cr(CO)3: New Reagents for Carbon-Carbon Bond Formation
Heppert, Joseph A.,Thomas-Miller, M. Elizabeth,Swepston, Paul N.,Extine, Michael W.
, p. 280 - 282 (1988)
The reaction of Na2 and (η6-ClC6H5)Cr(CO)3 in tetrahydrofuran N-methylpyrrolidinone (THF/NMP) produces Na6-C6H5)Cr(CO)3>, while various (η6-o-LiXC6H4)Cr(CO)3 derivatives react with Fe(CO)5 to produce L
