697302-50-4Relevant articles and documents
Dimeric boroles: Effective sources of monomeric boroles for heterocycle synthesis
Su, Xiaojun,Baker,Martin, Caleb D.
, p. 126 - 131 (2019/12/30)
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.
Experimental and theoretical study of the substituted (η6-arene)Cr(CO)3 complexes
Purwoko, Agus Abhi,Hadisaputra, Saprizal
, p. 717 - 724 (2017/05/26)
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.
A halogenophilic pathway in the reactions of transition metal carbonyl anions with [(η6-iodobenzene)Cr(CO)3]
Sazonov, Petr K.,Ivushkin, Vasiliy A.,Khrustalev, Victor N.,Kolotyrkina, Natal'Ya G.,Beletskaya, Irina P.
, p. 13392 - 13398 (2014/11/07)
The paper provides the first example of formal nucleophilic substitution by the halogenophilic pathway in Cr(CO)3 complexes of haloarenes with metal carbonyl anions. All metal carbonyl anions examined attack [(η6-iodobenzene)Cr(CO)3] at halogen, which is shown by aryl carbanion scavenging with t-BuOH. The reaction with K[CpFe(CO) 2] gives only the dehalogenated arene, but the reaction with K[Cp*Fe(CO)2] (Cp* = η5-C 5Me5) results in nucleophilic substitution to give [(η6-C6H5FeCp*(CO) 2)Cr(CO)3]. Reaction with Na[Re(CO)5] quantitatively gives the iodo(acyl)rhenate anion Na[(η6-C 6H5C(O)ReI(CO)4)Cr(CO)3] and in the case of K[Mn(CO)5] a mixture of σ-aryl complexes [(η6-C6H5Mn(CO)5)Cr(CO) 3] and K[(η6-C6H5Mn(CO) 4I)Cr(CO)3]. An analogous rhenium complex Na[(η6-C6H5Re(CO)4I)Cr(CO) 3] is formed from the initial iodo(acyl)rhenate upon prolonged standing at 20 °C, and its structure (in the form of [NEt4] + salt) is established by X-ray diffraction analysis. The reaction of [(η6-chlorobenzene)Cr(CO)3] with K[CpFe(CO) 2], in contrast, proceeds by the common SN2Ar mechanism.
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.
[2+4] Cycloaddition of η6-(styrene)chromium tricarbonyl and conjugated dienes
Artemov,Sazonova,Revin,Rybkin,Lazarev,Faerman
, p. 2103 - 2106 (2012/09/22)
Cycloaddition of η6-(styrene)chromium tricarbonyl to hexa-2,4-diene or cyclopentadiene afford the Diels-Alder adducts with retention of the Cr(CO)3 group, whereas cyclohexa-1,3-diene undergoes aromatization to give η6-(ben
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 (2008/10/09)
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.
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
Characterization and reactions of previously elusive 17-electron cations: Electrochemical oxidations of (C6H6)Cr(CO)3 and (C5H5)Co(CO)2 in the presence of [B(C6F5)4]
Camire, Nicole,Nafady, Ayman,Geiger, William E.
, p. 7260 - 7261 (2007/10/03)
The electrochemical oxidations of (C6H6)Cr(CO)3, 1, and (C5H5)Co(CO)2, 2, when carried out in CH2Cl2/[NBu4][B(C6F5)4], allow the physical or chemical characterization of the 17-electron cations 1+ and 2+ at room temperature. The generation of 1+ on a synthetic time scale permits an electrochemical switch process involving facile substitution of CO by PPh3 as a route to (C6H6)Cr(CO)2PPh3. The radical 2+ undergoes a second-order reaction to give a product assigned as the metal-metal bonded dimer dication [Cp2Co2(CO)4]2+. The new anodic chemistry of these often-studied 18-electron compounds is made possible by increases in the solubility and thermal stability of the cation radicals in media containing the poorly nucleophilic anion [B(C6F5)4]-, TFAB. Copyright
Photochemical synthesis of new (η6-arene)Cr-hydrido stannyl and (η6-arene)Cr-bis-stannyl complexes. Ligand effects on the Sn-H interaction in the hydrido stannyl compounds
Khaleel, Abbas,Klabunde, Kenneth J.,Johnson, Alison
, p. 11 - 20 (2007/10/03)
Hydrido stannyl compounds containing the η2-H-SnPh3 ligand and bis-stannyl compounds containing two SnPh3 ligands have been obtained from the photolysis of (η6-arene)Cr(CO)3 and HSnPh3. New complexes with different arenes (mesitylene, trifluorotoluene and 1,4-dimethoxybenzene) have been obtained and characterized by X-ray diffraction: (η6-C6H4(OCH3) 2)Cr(CO)2(HSnPh3) (3a), (η6-C6H4(OCH3) 2)Cr(CO)2(SnPh3)2 (3b). Structural data for 3a: monoclinic; space group P21/c (No. 14); a=17.445(3), b=9.820(3) and c=16.302(5) A; Z=4; V=2539.2(12) A3; 3b: monoclinic; space group P21/n (No. 14); a=13.904(3), b=20.567(5) and c=13.911(3) A; Z=4; V=3994(2) A3. 1H-NMR as well as X-ray provided evidence for the existence of three-center two-electron bonds in the hydrido stannyl complexes. The effects of different ligands on bonding and spectroscopic parameters were studied. Arene exchange reactions of the bis-stannyl complexes, as well as reactions of some of these compounds with P(C2H5)3 and CO, were also investigated.
Asymmetric synthesis of sulfinyl-substituted arene chromium tricarbonyl complexes
Davies, Stephen G.,Loveridge, Tracey,Teixeira, M. Fatima C. C.,Clough, John M.
, p. 3405 - 3412 (2007/10/03)
The synthesis of (SRSs[(phenylsulfinyl)benzene] chromium tricarbonyl 5 and (SRSs)-[(p-tolylsulfiny))benzene] chromium tricarbonyl 6 is achieved via a nucleophilic displacement reaction between the anion derived from (benzene) chromium tricarbonyl 9 and a suitable sulfinate ester. Replacing the sulfinate ester with a chiral sulfinyl-transfer reagent allows the isolation of the non-racemic sulfinyl-substituted complexes with good enantioselectivities (ee 80-89%) under optimised conditions. The use of Kagan's cyclic sulfite methodology for the synthesis of an enantiomerically pure tert-butylsulfinyl complex is unsuccessful, but results in the identification of a novel fragmentation - isomerisation process of the intermediate sulfinate. The Royal Society of Chemistry 1999.
