12083-24-8Relevant academic research and scientific papers
Photoinduced [6 + 2] cycloadditions of alkynes to tricarbonyl(cycloheptatriene)chromium(0)
Chaffee, Karen,Sheridan, John B.,Aistars, Arnis
, p. 18 - 19 (1992)
Photolysis of [(η6-C7H8)Cr(CO)3] (1) and RC≡ CR (2a, R = Ph; 2b, R = Tol) in toluene or n-hexane results in the formation of [(η2:η4-C9H8R 2)Cr(CO)3] (3a,b) in 70-85% isolated yield via a [6 + 2] cycloaddition reaction. Heating 3a,b in toluene gives the bicyclo[4.2.1]-nona-2,4,7-trienes 4a,b and [(η-C6H6Me)Cr(CO)3]. Photolysis of 1 and excess DMAD (dimethyl acetylenedicarboxylate, 5) in toluene at 0°C yields the bicyclotriene 4c as the major product and small amounts of the arene C6(CO2Me)6 and the [4 + 2] cycloadduct between 4c and 5.
Syntheses, crystal structures, and density functional theory calculations of the closo-[1-M(CO)3(η4-E9)]4- (E = Sn, Pb; M = Mo, W) cluster anions and solution NMR spectroscopic characterization of [1-M(CO)3(η4-Sn9)]4- (M = Cr, Mo, W)
Campbell, Janette,Mercier, Helene P.A.,Franke, Holger,Santry, David P.,Dixon, David A.,Schrobilgen, Gary J.
, p. 86 - 107 (2002)
The closo-[1-M(CO)3(η4-E9)]4- (E = Sn, Pb; M = Mo, W) anions have been obtained by extracting the binary alloys KSn2.05 and KPb2.26 in ethylenediamine (en) in the presence of 2,2,2-crypt or in liquid NH3 followed by reaction with M(CO)3·mes (M = Mo, W) or Cr(CO)3·tol in en or liquid NH3 solution. Crystallization of the molybdenum and tungsten salts was induced by vapor diffusion of tetrahydrofuran into the en solutions. The salts [2,2,2-crypt-K]4[1-M(CO)3 (η4-Sn9)]·en (M = Mo, W) crystallize in the triclinic system, space group P1, Z = 4, a = 16.187(3) A, b = 25.832(4) A, c = 29.855(5) A, α = 111.46(1)°, β = 102.84(2)°, γ = 92.87(2)° at -95 °C (M = Mo) and a = 17.018(3) A, b = 27.057(5) A, c = 28.298(6) A, α = 66.42(3)°, β = 76.72(3)°, γ = 87.27(3)° at 20 °C (M = W). The salts (CO)3M(en)2[2,2,2-crypt-K]4 [1-M(CO)3(η4-Pb9)]·2.5en (M = Mo, W) crystallize in the triclinic system, space group P1, Z = 2, a = 16.319(3) A, b = 17.078(3) A, c = 24.827(5) A, α = 71.82(3)°, β = 83.01(3)°, γ = 81.73(3)° at -133 °C (M = Mo) and a = 16.283(4) A, b = 17.094(3) A, c = 24.872(6) A, α = 71.62(2)°, β = 82.91(2)°, γ = 81.35(2)° at -153 °C (M = W). The [1-M(CO)3(η4-Sn9)]4- anions were also characterized in liquid NH3 solution by 119Sn, 117Sn, and 95Mo NMR spectroscopy. Unlike their fluxional precursor, nido-Sn94-, NMR studies show that the [1-M(CO)3(η4-Sn9)]4- anions are rigid on the NMR time scale. All possible inter- and intraenvironmental couplings, J(119,117Sn119,117Sn), J(119, 117Sn-183W), and one J(119, 117Sn-95Mo) coupling, have been observed and assigned. Complete spin-spin coupling constant assignments were achieved by detailed analyses and simulations of all spin multiplets that comprise the 119Sn and 117Sn NMR spectra and that arise from natural abundance tin isotopomer distributions and from natural abundance 183W, in the case of [1-W(CO)3(η4-Sn9)]4-. Both the solid state and solution structures of the [1-M(CO)3(η4-Sn9)]4- anions are based on a closo-bicapped square antiprismatic structure in which the transition metal occupies a cap position. The cluster structures are consistent with Wade's rules for 22 (2n + 2) skeletal electron systems. Electron structure calculations at the density functional theory (DFT) level provide fully optimized geometries that are in agreement with the experimental structures. Complete assignment of the NMR spectra was also aided by GIAO calculations. The calculated vibrational frequencies of the E94- and [1-M(CO)3(η4-E9)]4- anions are also reported and are used to assign the solid-state vibrational spectra of the [1-M(CO)3(η4-E9)]4- anions.
Stability and the gas chromatography of alkyl-substituted η6-benzenetricarbonylchromium(0) complexes
Patsalides, E.,Pratten, S. J.,Robards, K.
, p. 169 - 180 (1989)
Thermoanalytical and gas chromatographic data are reported for benzenetricarbonylchromium(0) and nine of its methyl- and t-butyl-substituted derivatives.The distinct trends found for the volatilities, thermal stabilities, air stabilities and gas chromatog
The reactions of group VI metal carbonyls with pyrrolidine, piperazine, and morpholine
Fowles,Jenkins
, p. 257 - 259 (1964)
Pyrrolidine and morpholine react with group VI metal carbonyls to give simple substituted products LnM(CO)6- n, where n = 1 and 2. Piperazine reacts with excess of Mo(CO)6 and W(CO)6 to give (C4H
Direct synthesis of (η6-arene)-tricarbonylchromium complexes by arene displacement from tricarbonyl(η5-1-methylpyrrole)chromium(0)
Goti, Andrea,Semmelhack, Martin F.
, p. C4 - C7 (1994)
Arene displacement from the title complex occurs under unprecedented mild conditions in neutral media to afford (η6-arene)tricarbonylchromium complexes.The process is most effective with heteroaromatic compounds: the first synthesis of a tricarbonyl(η6-quinoline)chromium complex and the diastereoselective preparation of a (η6-indole) complex derived from L-tryptophan are reported as representative examples.Key words: Chromium; Arene; Pyrrole; Quinoline; Indole; Diastereoselectivity
A KINETIC INVESTIGATION OF ARENE EXCHANGE AND SUBSTITUTION IN (NAPHTHALENE)Cr(CO)3
Howell, James A. S.,Dixon, Denis T.,Kola, John C.,Ashford, Neil F.
, p. C1 - C4 (1985)
The rate of (naphthalene)Cr(CO)3 with toluene in n-nonane to give (toluene)Cr(CO)3 is independent of the toluene concentration, whereas the rate of substitution by P(OMe)3 to give fac-Cr(CO)33 is first order with respect to the concentration of P(OMe)3.For a series of aromatic and heteroaromatic complexes of tricarbonylchromium, the order of substitutional lability is not necessarily mirrored in lability towards exchange.
Reactivity of some "ladder" type complexes under conditions of metallation
Orlova,Nekrasov,Petrovskii,Ezernitskaya,Magdesieva,Milovanov,Butin
, p. 1785 - 1788 (1998)
The behavior of binuclear "ladder" type complexes FpL, where Fp = Cp(CO)2Fe, L = p-MeC6H4Cr(CO)3 (4), CH2C6H5Cr(CO)3 (5), and p-FpC6H4Cr(CO)
Organometallic chemistry in supercritical fluids: The generation and detection of dinitrogen and nonclassical dihydrogen complexes of group 6, 7, and 8 transition metals at room temperature
Howdle, Steven M.,Healy, Michael A.,Poliakoff, Martyn
, p. 4804 - 4813 (1990)
The complete miscibility of N2 and H2 with supercritical fluids is used to stabilize unstable, and previously unknown, dinitrogen and dihydrogen complexes which would normally decay rapidly at ambient temperatures. UV photolysis of a series of (CnRn)M(CO)3 compounds [M = Fe, Mn, Re or Cr; R = H for n = 4; R = H or Me for n = 5 or 6] dissolved in supercritical Xenon (scXe) under a high pressure of N2 or H2 leads to the formation of (CnRn(CO)2(N2) and (CnR2)M(CO)2(H2) complexes at room temperature. Re and Fe undergo facile substitution of more than one CO group by N2, while Cr and Mn do not. For all elements except Re, the spectroscopic evidence suggests that the (CnRn)M(CO)2(H2) complexes contain the nonclassical η2 H2 ligand. No IR bands directly associated with η2-H2 in these compounds have been observed, but the experiments were sufficiently sensitive to detect the ν(H-H) band of W(CO)5(H2) under similar conditions. Most of these dihydrogen complexes decompose by reaction with CO to regenerate the (CnRn)M(CO)3 starting material, but significant amounts of Fe(CO)5 are formed in the decay of (C4H4)Fe(CO)2(H2). Kinetic measurements between 11 and 80 °C show that (C6H5Me)Cr(CO)2(H2) reacts with CO with an activation energy of 70 ±5 kj mol-1, which may correspond to the Cr-(η2-H2) bond dissociation energy.
N -heteropolycyclic compounds from the formal intramolecular (4 + 1)-cycloaddition of chromium aminocarbenes
Dery, Martin,Lefebvre, Louis-Philippe D.,Aissa, Kevin,Spino, Claude
supporting information, p. 5456 - 5459 (2013/11/19)
Chromium aminocarbenes tethered to dienes of all three electronic natures undergo an efficient intramolecular (4 + 1)-cycloaddition to give N-heteropolycyclic compounds. Ligands on chromium had a profound effect on the course of the reaction.
Palladium-catalyzed allylic substitution with (η6-Arene- CH2Z)Cr(CO)3-based nucleophiles
Zhang, Jiadi,Stanciu, Corneliu,Wang, Beibei,Hussain, Mahmud M.,Da, Chao-Shan,Carroll, Patrick J.,Dreher, Spencer D.,Walsh, Patrick J.
, p. 20552 - 20560 (2012/02/13)
Although the palladium-catalyzed Tsuji-Trost allylic substitution reaction has been intensively studied, there is a lack of general methods to employ simple benzylic nucleophiles. Such a method would facilitate access to "α-2-propenyl benzyl" motifs, which are common structural motifs in bioactive compounds and natural products. We report herein the palladium-catalyzed allylation reaction of toluene-derived pronucleophiles activated by tricarbonylchromium. A variety of cyclic and acyclic allylic electrophiles can be employed with in situ generated (η6-C 6H5CHLiR)Cr(CO)3 nucleophiles. Catalyst identification was performed by high throughput experimentation (HTE) and led to the Xantphos/palladium hit, which proved to be a general catalyst for this class of reactions. In addition to η6-toluene complexes, benzyl amine and ether derivatives (η6-C6H5CH 2Z)Cr(CO)3 (Z = NR2, OR) are also viable pronucleophiles, allowing C-C bond-formation α to heteroatoms with excellent yields. Finally, a tandem allylic substitution/demetalation procedure is described that affords the corresponding metal-free allylic substitution products. This method will be a valuable complement to the existing arsenal of nucleophiles with applications in allylic substitution reactions.
