12116-44-8Relevant articles and documents
Tuning reactivity and site selectivity of simple arenes in C-H activation: Ortho-arylation of anisoles via arene-metal π-Complexation
Ricci, Paolo,Kr?mer, Katrina,Larrosa, Igor
, p. 18082 - 18086 (2014)
Current approaches to achieve site selectivity in the C-H activation of arenes involve the use of directing groups or highly electron-poor arenes. In contrast, simple arenes, such as anisole, are characterized by poor reactivity and selectivity. We report
The potential of methylsiloxanes as solvents for synthetic chemistry applications
Ab Rani, Mohd Azri,Borduas, Nadine,Colquhoun, Victoria,Hanley, Robert,Johnson, Henry,Larger, Solene,Lickiss, Paul D.,Llopis-Mestre, Veronica,Luu, Selina,Mogstad, Martin,Oczipka, Philipp,Sherwood, James R.,Welton, Tom,Xing, Jun-Yi
, p. 1282 - 1296 (2014)
The potential use of volatile methylsiloxanes (VMSs) as solvents for chemicals synthesis has been explored. Assessment of the environmental impact of these VMS solvents is made and found to be significantly lower than those of the non-polar organic solvents that they have the potential to replace. The polarities of the VMSs, as expressed by empirical polarity measurements, and miscibilities with other liquids are found to be similar to those of alkane solvents. Finally, some uses of VMSs as solvents for both organic and inorganic transformations are described. The VMSs provide environmentally more sustainable (greener) alternatives to the nonpolar solvents that they have the potential to replace.
Synthesis and properties of Fischer carbene complexes of N,N-dimethylaniline and anisole π-coordinated to chromium tricarbonyl
Weststrate, Nora-ann,Bouwer, Shalane,Hassenrück, Christopher,van Jaarsveld, Nina A.,Liles, David C.,Winter, Rainer F.,Lotz, Simon
, p. 54 - 66 (2018)
The reaction of lithiated N,N-dimethylaniline π-coordinated to Cr(CO)3 with W(CO)6 and alkylation with [Et3O][BF4] afforded the o-, m- and p-isomers of the σ,π-bimetallic complexes {η6-Me2NC6H4C(OEt)W(CO)5}Cr(CO)3 (o-, 1, m-, 2 and p-isomer, 3). A by-product of the reaction is found by the substitution of a carbonyl ligand in 1 by the aniline nitrogen atom to give {η6-C,N-o-Me2NC6H4C(OEt)W(CO)4}Cr(CO)3 (4). As a result, the W-chelate ring dominates the HOMO rather than the{η6-arene Cr(CO)3} fragment, affecting the site of the first oxidation. Enhanced activation of anisole by π-coordination to Cr(CO)3, and subsequent reactions with nBuLi, W(CO)6 and [Et3O][BF4] gave only o-substituted products {μ,η6:1-o-MeOC6H4C(OEt)W(CO)5}Cr(CO)3 (5), the monocarbene chelate {μ,η6:2-C,O-o-MeOC6H4C(OEt)W(CO)4}Cr(CO)3 (6) by carbonyl substitution, and by reaction of two molar equivalents of these reagents, the unique σ,π-heterotrimetallic biscarbene complex {μ3,η6:1:1-o,o-MeOC6H3(C(OEt)W(CO)5)2}Cr(CO)3 (7). Attempts to synthesise the m- and p-isomers of 5 were unsuccessful due to transmetallation of the lithiated precursors. NMR data confirmed that lithiation and subsequent reactions of m- or p-bromoanisole chromiumtricarbonyl afforded only the o-isomer 5 and {η6-MeOC6H5}Cr(CO)3. Crystal structure determinations of complexes 1–7 confirmed their molecular structures. Spectroscopic data, electrochemistry studies and DFT calculations of the complexes are reported and are in line with a shifting of the HOMO from the Cr(CO)3 to the W(CO)4 chelate entity and with an unusually large delocalization of the HOMO of the other complexes onto the π-coordinated arene ligand and the carbene-bonded metal atom.
Intramolecular CO ... H interaction in Arene(tricarbonyl)-chromium complexes
Bodrikov,Grinval'D,Artemov,Bazhan,Kalagaev, I. Yu.
, p. 20 - 22 (2010)
Unlike benzene(tricarbonyl)chromium which displays two carbonyl stretching vibrations bands in the IR spectrum, analogous tricarbonylchromium complexes of the general formula (C6H5ZMe)Cr(CO)3 [Z = O, CH(OH), N(Pr), CH=CH]
ELEKTRONENSTOSS-INDUZIERTER ZERFALL VON BENZOL-TRICARBONYL-CHROM- UND -WOLFRAM-DERIVATEN; EIN VERGLEICH
Mueller, Joern,Luedemann, Frerk
, p. 361 - 376 (1981)
The electron impact mass spectra of (CO)3MC6H5-X complexes (M = Cr, W; X = OCH3, OC4H9, CO2CH3, CO2C4H9) were recorded.From metastable transitions and by high-resolution measurements complete fragmentation diagrams were obtained; in some cases comparative
Probing "microwave effects" using Raman spectroscopy
Schmink, Jason R.,Leadbeater, Nicholas E.
, p. 3842 - 3846 (2009)
The use of in situ Raman spectroscopy is reported as a tool for probing the effects of microwave irradiation on molecules. Our results show no evidence for localized superheating, an often-cited specific microwave effect. While the microwave energy may in
ortho-Directing Chromium Arene Complexes as Efficient Mediators for Enantiospecific C(sp2)–C(sp3) Cross-Coupling Reactions
Bigler, Raphael,Aggarwal, Varinder K.
, p. 1082 - 1086 (2018)
A new strategy for the coupling of a broad scope of electronically diverse aromatics to boronic esters is reported. The coupling sequence, which relies on the directed ortho-lithiation of chromium arene complexes followed by boronate formation and oxidation, occurs with complete ortho-selectivity and enantiospecificity to give the coupling products in excellent yields and with high functional group tolerance. An intermediate chromium arene boronate complex was characterized by X-ray, NMR, and IR experiments to elucidate the reaction mechanism.
A laser flash photolysis, matrix isolation, and DFT investigation of (η6-C6H5Y)Cr(CO)3 (Y = NH2, OCH3, H, CHO, or CO2CH3)
Alamiry, Mohammed A.H.,Brennan, Peter,Long, Conor,Pryce, Mary T.
, p. 2907 - 2914 (2008/12/21)
The quantum yield for arene displacement from (η6-C6H5Y)Cr(CO)3 was measured in 1,1,2-trifluorotrichloroethane (Y = NH2, OCH3, H, CHO, or CO2CH3). Values of 0.24, 0.27, 0.15, 0.17, and 0.32 were obtained respectively (λexc. = 355 nm). These values are significantly higher than those measured for photoinduced arene loss in hydrocarbon solvents using the same excitation wavelength. Laser flash photolysis of (η6-C6H5Y)Cr(CO)3 in 1,1,2-trifluorotrichloroethane (λexc. = 355 nm) resulted in the rapid formation (6. Matrix isolation experiments on (η6-C6H5Y)Cr(CO)3 (Y = H or CHO) at 12 K in CH4 or CO-doped CH4 matrixes using monochromatic irradiation confirmed the presence of two discrete excited states, one leading to CO-loss and the other to arene-loss. The results correlate with the calculated electron drift in the excited state derived from density functional theory and time dependent density functional theory calculations.
Organometallic chemistry in a conventional microwave oven: The facile synthesis of group 6 carbonyl complexes
Ardon, Michael,Hogarth, Graeme,Oscroft, Daniel T.W.
, p. 2429 - 2435 (2007/10/03)
Syntheses proceeding by reflux may be improved, accelerated and simplified, by carrying out the reaction in a modified conventional microwave oven. To demonstrate the potential of this method, the synthesis of over 20 group 6 organometallic compounds is reported. Hexacarbonyls, most notably Mo(CO)6, react with a range of mono, and bi, and tridentate ligands in a modified conventional microwave oven. They generally proceed without an inert atmosphere, yields are high and reaction times are short. For example, cis -[Mo(CO)4(dppe)] is prepared in >95% yield in 20 min. Reaction of Mo(CO)6 with dicyclopentadiene affords a simple one-step synthesis of [CpMo(CO)3]2 in >90% yield, which reacts further with alkynes in toluene to produce dimetallatetrahedrane derivatives, [Cp2Mo2(CO)4 (μ-RC2R)]; presumably via the in situ formation of air-sensitive [CpMo(CO)2]2. Dimolybdenum tetra-acetate is also prepared in 48% yield in 45 min, however, this reaction requires an inert atmosphere. While W(CO)6 reacts rapidly with amines to give cis diamine adducts in high yields, direct reactions with phosphines are not so clean. Bis(phosphine) complexes are, however, cleanly formed when a small amount of piperidine is added to the reaction mixture, presumably via the bis(piperidine) complex cis-[W(CO)4(pip)2]. Reactions with Cr(CO)6 generally require an inert atmosphere and proceed less cleanly, although the important synthon [Cr(CO)5 Cl][NEt4] was prepared in 30 min (74% yield), while [(η6-C6H5OMe)Cr(CO)3] can be prepared in 45% after 4 h.
Addition reactions of lithiodimethylphenylsilane to (η4-1,3-diene)-Fe(CO)3 and (η6-arene)Cr(CO)3 complexes
Yeh, Ming-Chang P.,Sheu, Peng-Yu,Ho, Jin-Xuan,Chiang, Yi-Lin,Chiu, Dai-Yu,Narasimha Rao
, p. 13 - 20 (2007/10/03)
Treatments of (η4-cyclohexa-1,3-diene)Fe(CO)3 complex with 1.2 equivalents of PhMe2SiLi, followed by quenching the reactive intermediate with CF3COOH generated 1-dimethyl(phenyl)silylcyclohex-1-ene and with 2-(p
