12082-08-5Relevant articles and documents
Johnson, Brian F. G.,Lewis, Jack,Wege, Dieter
, (1976)
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.
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.
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.
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
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
Rotational barriers in substituted (cycloheptatriene)Cr(CO)3 complexes
Reynolds, Stephen D.,Albright
, p. 980 - 986 (1985)
The barriers of rotation about the cycloheptatriene-Cr axis have been determined for six (7-substituted cycloheptatriene)Cr(CO)3 complexes. The barriers were determined from a complete line-shape analysis of the 13C spectra for the carbonyl region as a function of temperature. The values of ΔH? for the cycloheptatriene (CHT), 7-exo-MeCHT, 7-endo-MeOCHT, and 7,7-di-MeOCHT complexes are essentially identical (9.9 ± 0.2,10.4 ± 0.5, 9.9 ± 0.3, and 9.9 ± 0.4 kcal/mol, respectively) and the values of ΔS? cluster around zero. On the other hand, ΔH? values for 7-exo-CNCHTCr(CO)3 (8.9 ± 0.2 kcal/mol) and 7-exo-t-BuCHTCr(CO)3 (10.9 ± 0.3 kcal/mol) are, respectively, slightly lower and higher than these values. This appears to be consistent with arguments concerning the electronic origin of these rotational barriers, namely, that the magnitude of the barrier is related to the cycloheptatriene-norcaradiene equilibrium. Estimates of the rotational barriers in three (1,6-methanoannulene)Cr(CO)3 complexes are also consistent with this theory. Finally the barrier in (tropone)Cr(CO)3 was found to be very small (～6 kcal/mol); extended Hu?ckel molecular orbital calculations predict a barrier of 5.8 kcal/mol. A rationale why the barrier in this complex is much lower than the other cycloheptatriene complexes is given.
THE HEATS OF IODINATION OF CHROMIUM TRICARBONYL COMPLEXES OF ARENES AND CYCLOHEPTATRIENE
Hoff, Carl D.
, p. C53 - C56 (1983)
The heats of iodination of chromium tricarbonyl complexes of benzene, toluene, mesitylene, and cycloheptatriene have been measured by solution calorimetry in tetrahydrofuran at 25 deg C.The order of the Cr-ligand strength is: mesitylene > cycloheptatriene
KINETIC CH-ACIDITY OF BENZENETRICARBONYLCHROMIUM AND ITS DERIVATIVES
Antonova, M. V.,Moiseev, S. K.,Kalinin, V. N.,Shapiro, I. O.
, (1989)
Kinetic acidities of aryl and benzyl CH-bonds for complexes of benzene and its methoxy and alkyl derivatives with tricarbonylchromium are determined in a solution of lithium tert-butoxide in N,N-dimethylacetamide.Complexation of alkyl-aromatic compounds t
Experimental and theoretical study of the substituted (η6-arene)Cr(CO)3 complexes
Purwoko, Agus Abhi,Hadisaputra, Saprizal
, p. 717 - 724 (2017)
Synthesis of arenetricarbonylchromium(0) complexes, [(η6-arene)Cr(CO)3], has been carried out, wherein arene were benzene (Ph), chlorobenzene (PhCl), phenyl trimethyl silane (PhSiMe3), and acenaphthene (PhNp). Characterization of the compounds was carried out using NMR, IR and UV-visible spectrophotometers. Electronic absorption of these complexes were measured in various solvents namely methanol, methylene chloride, chloroform, benzene, and isooctane. The complexes showed the electronic absorption of the lowest in the energy range of 313-320 nm, with a relatively high intensity. Density functional theory at the B3LYP/LanL2DZ level of theory was also used to study the geometry parameters, binding energy (BE), vibrational spectra, electronic spectra, frontier molecular orbital (NBO analysis), charge transfer (CT) of the complexes. It was found that the order of the complex stability is: (PhSiMe3)Cr(CO)3> (Ph)Cr(CO)3> (PhNp)Cr(CO)3> (PhCl)Cr(CO)3. The NBO analysis showed that the stability of the complexes arising from intramolecular interactions and electron delocalization in which synergistic interaction occurs in the arene hyper conjugative orbital ring for metal antibonding orbital and back donation (via metal bonding orbital to bond antibonding orbital ring). The electronic spectrum shows the charge transfer is dominated by ligand to metal charge transfer (LMCT) transition, except for (PhNpe) Cr(CO)3 that is dominated by metal to ligand charge transfer (MLCT) and only a small portion is set to d-d transition.
Arene-metal π-complexation as a traceless reactivity enhancer for C-H arylation
Ricci, Paolo,Kraemer, Katrina,Cambeiro, Xacobe C.,Larrosa, Igor
supporting information, p. 13258 - 13261 (2013/09/24)
Current approaches to facilitate C-H arylation of arenes involve the use of either strongly electron-withdrawing substituents or directing groups. Both approaches require structural modification of the arene, limiting their generality. We present a new approach where C-H arylation is made possible without altering the connectivity of the arene via π-complexation of a Cr(CO)3 unit, greatly enhancing the reactivity of the aromatic C-H bonds. We apply this approach to monofluorobenzenes, highly unreactive arenes, which upon complexation become nearly as reactive as pentafluorobenzene itself in their couplings with iodoarenes. DFT calculations indicate that C-H activation via a concerted metalation-deprotonation transition state is facilitated by the predisposition of C-H bonds in (Ar-H)Cr(CO)3 to bend out of the aromatic plane.
