Chromium Tricarbonyl Research Articles

Coordination Polymers of Zinc with (η6-Benzenecarboxylate) Chromium Tricarbonyl

Different coordination polymers were obtained by the reaction of (benzoic acid) chromium tricarbonyl with zinc acetate in the presence of various organic dipyridyl linkers. Depending on the nature of the linker either monomeric or polymeric compounds were obtained. Reactions of (benzoic acid) chromium tricarbonyl with zinc acetate and bidentate pyridine based ligands 4,4'-bipyridine (4,4'-bipy), 1,2-bis(4-pyridyl)ethane (bpe), 1,3-bis(4-pyridyl)propane (tmdp), and 2,2'dipyridylamine (DPA) afforded the novel coordination polymers [Zn[{η(6)-C(6)H(5)COO}Cr(CO)(3)](2)(4,4'-bipy)](n), [Zn[{η(6)-C(6)H(5)COO}Cr(CO)(3)](2)(bpe)](n), [Zn[{η(6)-C(6)H(5)COO}Cr(CO)(3)](2)(tmdp)}](n), and the monomeric complex [Zn[{η(6)-C(6)H(5)COO}Cr(CO)(3)](2)(DPA)]. The solid state structures of all compounds were determined by single crystal X-ray diffraction. By using 1,3-bis(4-pyridyl)propane as a linker a chiral infinite helical structure was formed in the solid state. Thermogravimetric analysis (TGA) studies showed that upon heating the carbonyl groups of the {η(6)-C(6)H(5)COO}Cr(CO)(3) anion were lost before the organic ligand sphere was thermally decomposed.

Syntheses of chromium tricarbonyl organometals of 1-methyl-naphthalene and different polycyclic aromatic hydrocarbons, characterisation of the (C 11H 10)Cr(CO) 3 isomers and the crystal structure of the [( η6-5,6,7,8,9,10-C 11H 10)Cr(CO) 3] complex

The synthesis of organometal complexes from chromium hexacarbonyl with 1-methyl-naphthalene ligand is reported. Two arene-chromium-tricarbonyl isomers are formed at competitive yields, featured with the metal fragment coordinated to both the methylated and the benzenic aromatic ring. A single-crystal X-ray diffraction measurement has been performed on the [( η 6-5,6,7,8,9,10-C 11H 10)Cr(CO) 3] isomer, which presents the metal carbonyl moiety attached to the benzenic arene ligand. The products of reaction have been studied by UV–VIS–NIR, fluorescence and 1H NMR spectroscopies. A detailed vibrational characterisation by mean of experimental FT-IR and Raman spectroscopy and DFT calculations is reported. The electron ligand donation to the metal carbonyl system, determined by FT-IR spectroscopy, has been related to the actual decrease of resonance energy of the aromatic hydrocarbon in the complex and compared with other chromium tricarbonyl complexes of different polycyclic aromatic hydrocarbons provided with the naphthalenic moiety.

Vibrational Spectra of Benzene Chromium Tricarbonyl and Its Mesityl Analogue: A Study by Neutron Spectroscopy

We have used high resolution neutron vibrational spectroscopy to study the vibrations of the model compound for arene-to-metal bonding, benzene chromium tricarbonyl, and its mesityl analogue. It is shown that all previously published assignment schemes, based on optical spectroscopy alone, are wrong, and new assignments are given in agreement with ab initio calculations.

Hydroquinoid Chromium Complexes Bearing an Acyclic Conjugated Bridge: Chromium-Templated Synthesis, Molecular Structure, and Haptotropic Metal Migration

The naphthohydroquinoid tricarbonyl chromium complexes 3 and 6, bearing a styryl or phenylazo moiety, have been synthesized and studied for the haptotropic metal migration along the extended π-system. Quantum chemical calculations suggested a feasible stepwise rearrangement of the Cr(CO)3 fragment from the hydroquinoid to the other terminal phenyl ring for the azo- rather than for the ethene-bridged system. An experimental and kinetic study of the ethene-bridged complex 3 revealed a haptotropic metal shift onto the adjacent naphthalene ring to give isomer 7 and suggested a competing intermolecular decomplexation−recomplexation pathway for the coordination of the terminal phenyl ring, affording bismetalated complexes 8 and 9. Attempts of a controlled metal migration in the azo complex analogue 6 under similar conditions were unsuccessful and resulted in partial decomposition.

Efficient Enantioselective Syntheses of Sertraline, 2‐Epicatalponol and Catalponol from Tetralin‐1,4‐dione

AbstractTetralin‐1,4‐dione, the stable tautomer of dihydroxynaphthalene, was reduced with catecholborane in the presence of 3,3‐diphenyl‐1‐butyltetrahydro‐3H‐pyrrolo[1,2‐c][1,3,2]oxazaborole as catalyst to give enantiomerically highly enriched 4‐hydroxy‐1‐tetralone (99% ee) in an efficient one‐pot procedure. The R‐enantiomer provided a rapid access to sertraline while the S‐enantiomer was converted into 2‐epicatalponol and catalponol. A more selective enantioselective route to the antithermitic catalponol made use of the planar chiral tricarbonylchromium complex of hydroxytetralone. Its precursor chromium(tricarbonyl)[η6‐(1‐4,4a,8a)‐tetralin‐5,8‐dione] was obtained via direct complexation of 1,4‐dihydroxynaphthalene using chromium(tricarbonyl)‐ tris(ammonia) and boron trifluoride etherate as source of the chromium(tricarbonyl) fragment. Enolate prenylation was best carried out in the presence of a tetraamine ligand. Complete inversion of the stereogenic center bearing the prenyl group of the initially obtained tetralone complex was achieved via enolate formation followed by protonation.

ChemInform Abstract: Synthesis and Molecular and Crystal Structures of (3-Methyl-3- benzoborepin)chromium Tricarbonyl.

(3-Methyl-3-benzoborepin) chromium tricarbonyl was obtained by treating the free ligand with tris-(acetonitrile) chromium tricarbonyl in refluxing tetrahydrofuran. Red crystals of the complex C 14 H 11 BCrO 3 form in the P2 1 /n space group

ChemInform Abstract: Synthesis and Structure of Phosphazene-(η6-Arene)chromium Tricarbonyl Derivatives.

ChemInform Abstract: Synthesis and Structure of Phosphazene-(η6-Arene)chromium Tricarbonyl Derivatives.

ChemInform Abstract: Stereocontrolled Synthesis of Exocyclic Olefins Using Arene Tricarbonyl Chromium Complex-Catalyzed Hydrogenation. Part 2. A Catalytic Asymmetric Synthesis of an Anthracycline Intermediate.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Enantioselective Conjugate Addition of Diethylzinc to Chalcone Catalyzed by Chiral Tricarbonyl(arene)chromium/Nickel(II).

Abstract Enantioselective conjugate addition of diethylzinc to chalcone in the presence of Ni(acac)2 complexed with chiral tricarbonyl(1,2-disubstituted arene)chromium gave addition products with up to 78 % ee depending upon the amounts of Ni(II) and chiral arene chromium complexes.

ChemInform Abstract: Stereoselective Manipulation of Acetals Derived from o-Substituted Benzaldehyde Chromium Tricarbonyl Complexes

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Chiral Arene Chromium Tricarbonyl Complexes as Enantioselective Catalysts: Highly Selective 1,2-Alkyl Additions to Aldehydes.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Dimethyldioxirane in Organometallic Chemistry: A Convenient Procedure for the Decomplexation of Arene Chromium Tricarbonyl Compounds.

Abstract Arene chromium tricarbonyl complexes 1 react with dimethyldioxirane to give the corresponding arene derivatives 2 in quantitative yields. The reaction is rapid, highly chemoselective and involves an easy manipulation procedure. In addition, the reaction course could be monitored by colour change, thus avoiding the possible further oxidation of substituents linked to the aromatic ring. However, the complex with thioanisole was chemoselectively oxidized with dimethyldioxirane to the corresponding sulfoxide complex.

ChemInform Abstract: Highly Stereocontrolled Asymmetric Syntheses of Taxol and Taxotere C- 13 Side-Chain Analogues.

Abstract Asymmetric aldol reaction of (+)-tricarbonyl(η 6 -2-trimethylsilylbenzaldehyde)chromium(0) complex ( 4 ) with titanium enolate of S-tert -butyl benzyloxyethanethioate ( 10 ) provided, after consecutive desilylation and decomplexation, anti -aldol product 15 in a highly stereoselective manner. Anti -product 15 was subsequently converted to (2R,3S)- N -benzoyl- and N-tert -butoxycarbonyl-3-phenylisoserine methyl esters ( 23 and 24 ), C-13 side chain analogues of taxol ( 1 ) and taxotere ( 2 ).

Origin of the regioselectivity in an intramolecular nucleophilic addition to arene chromium tricarbonyl complexes

The source of the regioselectivity in the intramolecular nucleophilic addition of nitrile-stabilized carbanions to arene chromium tricarbonyl complexes was investigated for seven different substitution patterns on the arenes. All of the arenes are 1,4-dioxygenated and the substitution varies in the oxygen substituent and in the substituents of the arene carbons (hydrogen and alkyl). The regioselectivity is correlated with the preferred conformations of the chromium tricarbonyl group which in turn was determined by solution and solid-state 13C NMR spectroscopy, 1H NMR spectroscopy in solution as well as X-ray diffraction. In the four complexes analyzed by X-ray diffraction and the three complexes analyzed by solid-state 13C NMR spectroscopy, there was only one complex where it was found that the preferred conformation of the –Cr(CO) 3 is different in solution than it is in the solid-state.

The stereodivergent asymmetric synthesis of a range of 2-(1′-hydroxyalkyl)phenols

Abstract The use of the (S)-α-methylbenzyl group as a chiral auxiliary has allowed the diastereoselective ortho-deprotonation of a chromium tricarbonyl complexed phenoxy ring. When the resultant ortho-anion is treated with an aldehyde two diastereoisomeric complexes are formed, in relatively poor dr, which differ in the configuration of the newly formed benzylic stereogenic centre. However, both ortho-formylation followed by treatment with Grignard reagents and ortho-acylation followed by reduction with Super-Hydride® were found to be completely diastereoselective, giving access to either epimer of the corresponding benzylic alcohol complexes in >99:1 dr. Subsequent oxidative removal of the chromium tricarbonyl unit, followed by cleavage of the O-α-methylbenzyl chiral auxiliary gives enantiopure 2-(1′-hydroxyalkyl)phenols. Following this stereodivergent procedure, either enantiomer of the product may be accessed from a single antipode of [(α-methylbenzyloxy)benzene]Cr(CO)3.

SOLVATOCHROMIC AND SUBSTITUENT EFFECT ON ELECTRONIC ABSORPTION OF ARENETRICARBONYLCHROMIUM(0) COMPLEXES

A number of arenetricarbonylchromium(0) complexes, [(η6-arene)Cr(CO)3], in which arene = benzene, chlorobenzene, phenyltrimethylsilane, and acenaphthene were synthesized. Electronic absorptions of these complexes were recorded in various solvents, ranging from polar to non polar ones; i.e. methanol, methylene chloride, chloroform, benzene, and isooctane. These chromium tricarbonyl complexes show lowest electronic absorption in the energy range of 313 - 320 nm, with relatively high intensity (ε = 0,9 - 2,0 x 104 M-1cm-1). Detailed discussion of the solvent and substituent effect on electronic absorption of these complexes are presented in this article. Keywords: solvatochromic and substituent effect, chromium tricarbonyl complexes, electronic absorption

ChemInform Abstract: Stereoselective Route to Mitosanes via Tricarbonyl η6 Arene Chromium Complexes.

Abstract Stereoselective reduction followed by metalation of a η6 arene chromium tricarbonyl complex allows rapid access to substituted mitosanes, whose skeleton mimics the mitomycin family of antitumour agents.

ChemInform Abstract: Stereoselective Bis-functionalizations of Arene Chromium Tricarbonyl Complexes via Brook Rearrangements.

An efficient method has been developed for the stereoselective bis-functionalization of arene chromium tricarbonyl complexes. Initial nucleophilic addition of organolithium reagents to a carbonyl moiety is followed by a 1,4-carbon to oxygen silyl migration (Brook rearrangement) and alkylation of the resultant aryl anion.

ChemInform Abstract: Catalytic Enantioselective Cycloadditions: A Readily Available Diels-Alder Catalyst.

Abstract A highly selective Diels–Alder catalyst has been prepared from a commercially available tetrahydronaphthalene diol. Stereocontrol is enhanced by introduction of a planar chiral arene chromium tricarbonyl group.

ChemInform Abstract: Synthesis of Nitrile Ligands Bearing Tricarbonyl (η6-Arene)chromium Complexes and Conjugated Spacers.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.