Structure Of Tricarbonyl Research Articles

Fluorine Migration from Carbon to Iron and Fluorine–Iron Dative Bonds in Octafluorocyclohexadiene Iron Carbonyl Chemistry

The geometries and energies of mononuclear and binuclear octafluorocyclohexadiene iron carbonyl derivatives have been studied using density functional theory. The lowest energy C6F8Fe(CO)3 tricarbonyl structure is the octafluoro-1,3-cyclohexadiene derivative known experimentally. Isomeric structures containing the other two possible C6F8 hexagon ligands lie at higher energies. Unprecedented oxidative addition involving fluorine migration from carbon to iron is theoretically predicted in the C6F8Fe(CO)4 tetracarbonyl systems to give low-energy C6F7Fe(CO)4F structures. A similar energetically favored fluorine migration, also from carbon to iron, converts the coordinatively unsaturated (η4-C6F8)Fe(CO)2 dicarbonyl complex to the coordinatively saturated heptafluorocyclohexadienyl complex (η5-C6F7)Fe(CO)2F. For C6F8Fe2(CO)8, trans isomers with two Fe(CO)4 moieties on opposite sides of the C6F8 ring coordinated to C═C bonds are the lowest energy structures. These are similar to the experimentally known hexafluorocyclopentadiene complex C5F6[Fe(CO)4]2. The corresponding cis isomers with the Fe(CO)4 moieties on the same size of the C6F8 ring are high-energy structures, possibly a consequence of the steric hindrance between the two closely spaced Fe(CO)4 moieties. The low-energy C6F8Fe2(CO)7 structures may be viewed as the substitution products of the experimentally known Fe2(CO)9, with the two carbonyl groups replaced by a terminal or bridging C6F8 ligand donating four electrons to one or both iron atoms of the central Fe2 unit. The low-energy singlet structures in the unsaturated C6F8Fe2(CO)6 system have C6F8 ligands donating electrons to the central Fe2 system not only through Fe–C bonds but also through F→Fe dative bonds involving fluorine lone pairs.

Construction of reversible crosslinking–decrosslinking system consisting of a polymer bearing vicinal tricarbonyl structure and poly(ethylene glycol)

In this article, we report a novel reversible crosslinking–decrosslinking system consisting of a polymer bearing vicinal tricarbonyl moieties in its side chains and poly(ethylene glycol) (PEG). A mixture of the tricarbonyl polymer and PEG (0.1 equiv of OH groups relative to the vicinal tricarbonyl moieties) in CH2Cl2 spontaneously turned into an orange-colored gel, in which a network structure was formed through hemiketal linkages. Conversely, the resulting networked polymer could be decrosslinked by treatment with water-containing solvent to recover the linear vicinal tricarbonyl polymer as its hydrate in 90 % yield. Following dehydration process by heating at 100 °C under reduced pressure regenerated the original vicinal tricarbonyl polymer.

Crystal structure of tricarbon-yl(N-di-phenyl-phosphanyl-N,N'-diisopropyl-P-phenyl-phospho-nous di-amide-κ(2) P,P')cobalt(I) tetra-carbonyl-cobaltate(-I) toluene 0.25-solvate.

The asymmetric unit of the title compound, [Co(C24H30N2P2)(CO)3][Co(CO)4]·0.25C7H8, consists of two crystallographically independent cations with similar conformations, two anions, and one-half of a toluene mol-ecule disordered about an inversion centre. In the cations, a Co/P/N/P four-membered slightly bent metallacycle is the key structural element. The pendant NH group is not coordinated to the Co(I) atom, which displays a distorted trigonal-bipyramidal coordination geometry. Weak inter-ionic hydrogen bonds are observed between the NH groups and a carbonyl group of the tetrahedral [Co(CO)4](-) anions.

Methylborabenzene ligands in binuclear iron carbonyl derivatives: High spin states and iron–iron multiple bonding

The experimentally known methylborabenzene iron carbonyl (C5H5BCH3)2Fe2(CO)4 and its decarbonylation products (C5H5BCH3)2Fe2(CO)n (n = 3, 2) have been studied by density functional theory for comparison with their cyclopentadienyl analogs. The lowest energy (η6-C5H5BCH3)2Fe2(CO)4 structures are the experimentally known singlet doubly bridged cis-(η6-C5H5BCH3)2Fe2(CO)2(μ-CO)2 and the corresponding trans isomer similar to the corresponding (η5-C5H5)2Fe2(CO)2(μ-CO)2 system. Also the triplet triply bridged (η6-C5H5BCH3)2Fe2(μ-CO)3 is the lowest energy tricarbonyl structure similar to the cyclopentadienyl system. However, significant differences between the methylborabenzene and cyclopentadienyl derivatives are found in the dicarbonyl systems. A singlet (η5-C5H5)2Fe2(μ-CO)2 structure with a short FeFe distance of ∼2.1 Å was previously found to be the lowest energy structure in the cyclopentadienyl system. An analogous methylborabenzene structure (η6-C5H5BCH3)2Fe2(μ-CO)2 is found as the lowest energy singlet structure. However, an unsymmetrical quintet (η6-C5H5BCH3)FeFe(CO)2(η6-C5H5BCH3) structure is predicted to lie ∼22 kcal/mol below this singlet structure. The existence of this low-energy, high-spin (η6-C5H5BCH3)2Fe2(CO)2 structure makes (η6-C5H5BCH3)2Fe2(μ-CO)3 disfavored with respect to disproportionation into (η6-C5H5BCH3)2Fe2(μ-CO)4 + (η6-C5H5BCH3)2Fe2(μ-CO)2 unlike its cyclopentadienyl analog.

Synthesis and structure of tricarbonyl(η6-arene)chromium complexes of phenyl and benzyl D-glycopyranosides

A series of 15 glycoside-derived tricarbonyl(η6-arene)chromium complexes were prepared in 19–87% yield by heating fully acetylated or methylated aryl O-, S-, N- and C-glycosides of D-glucopyranose and D-mannopyranose with hexacarbonylchromium. All tricarbonylchromium complexes were fully characterized. The structures of nine crystalline complexes were determined by X-ray diffraction, revealing unusual intra- and intermolecular nonclassical hydrogen bonds.

Synthesis and reversible hydration–dehydration system of copolymers bearing a vicinal tricarbonyl structure

AbstractNovel copolymers composed of a styrene (St) derivative bearing a vicinal tricarbonyl moiety and various vinyl monomers such as St, methyl methacrylate (MMA), and N‐vinylpyrrolidone (NVP) were synthesized by (1) radical copolymerization of a St derivative with a 1,3‐diketone structure with St, MMA, and NVP and (2) successive oxidation of the resulting copolymers with N‐bromosuccinimide in DMSO to convert their 1,3‐diketone moieties in the side chains into the corresponding vicinal tricarbonyl moieties. Their tricarbonyl moieties were readily hydrated in water‐containing acetone to generate the corresponding copolymers bearing geminal diol structures in the side chains. On the other hand, heating the resulting copolymers bearing the geminal diol structures in vacuo‐enabled successful recovery of the vicinal tricarbonyl moieties to demonstrate the reversible nature of this system. The hydration behavior in powdery state under air atmosphere saturated by water was also investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Construction of reversible hydration–dehydration system by a model compound and a novel polymer bearing vicinal tricarbonyl structure

AbstractA novel polymer bearing acyclic vicinal tricarbonyl moieties in the side chains was synthesized by (1) radical polymerization of a styrene derivative with a 1,3‐diketone structure and (2) successive treatment of the resulting polystyrene derivative by N‐bromosuccinimide to convert its 1,3‐diketone moiety in the side chains into the corresponding vicinal tricarbonyl moiety. The tricarbonyl moiety was highly reactive with water to permit its rapid conversion into a geminal diol structure in water‐containing acetone. On the other hand, heating the resulting polymer bearing the geminal diol structure under vacuum enabled successful recovery of the vicinal tricarbonyl moiety to demonstrate the reversible nature of this system, which allowed us to repeat the hydration–dehydration cycle without deteriorating the polymer structure. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Synthesis, structure, and quantum-chemical study of tricarbonyl(4-methoxybenzaldehyde)chromium(0)

The structure of tricarbonyl(4-methoxybenzaldehyde)chromium(0) was studied by X-ray crystallography. The crystals are orthorhombic, space group P212121, a = 8.040(1) A, b = 10.510(7) A, c = 13.279(4) A, V = 1122.1(8) A3, Z = 4. Quantum-chemical calculations predict that this compound can exist in the gas phase as two stable conformers with almost the same energies. Their mutual transformations are examined using the density functional theory.

"As Simple as Possible, but Not Simpler"—The Case of Dehydroascorbic Acid

Ascorbic acid (vitamin C) is an essential nutrient, whose metabolic roles depend on its function as a reducing agent. Textbooks routinely assign its oxidized form, dehydroascorbic acid, a tricarbonyl structure that is highly improbable in aqueous solution and inconsistent with its colorless appearance. The actual structures of the various forms of dehydroascorbic acid have been known for at least a quarter of a century so that the continued use of the oversimplified tricarbonyl structure is hard to excuse. The experimental results on studies of oxidized forms of ascorbic acid are summarized here, and a plea is entered for accurate descriptions of chemical structures in this and other cases, even at the cost of some simplicity. A group exercise based on dehydroascorbic acid, which we have used in second-semester organic chemistry, is included in the online material.

Thermolysis of Iron N-Allylaminocarbene Complexes: Formation of η3-1-Azaallylirontricarbonyl Complexes. Synthetic and Theoretical Study

Both chelated and nonchelated N-allyl-N-methylaminocarbene complexes of iron unsubstituted at the 1- and 3-positions of an allyl substituent afforded by thermolysis new η3-iron tricarbonyl complexes of 2,3-dihydropyrrole. The proposed mechanism of these reactions involves bicyclo[2.1.1]-2-aza-5-ferrahexane as an intermediate formed by [2+2] cycloaddition. Formation of this intermediate requires antiparallel arrangement of FeC and CC double bonds in the cycloaddition step. This mechanism was supported by reaction of deuterium-labeled complexes and by the density functional calculations of B3LYP quality. The structure of tricarbonyl[(η3-N-methyl-2-(biphenyl-4-yl)-4,5-dihydropyrrole]iron(0) (4f) has been determined by X-ray diffraction.

Crystal structure of tricarbonyl-{η6 -[dimethyl 2-methoxy-2-(2-methoxycarbonylphenyl)] malonate} chromium(0), C17H16CrO10

Article Crystal structure of tricarbonyl-{η6 -[dimethyl 2-methoxy-2-(2-methoxycarbonylphenyl)] malonate} chromium(0), C17H16CrO10 was published on December 1, 1997 in the journal Zeitschrift für Kristallographie - New Crystal Structures (volume 212, issue 1).

Tetrafluoroborate Salt of Tricarbonyl(2-methoxy-η5-cyclohexadienyl)iron(II)

The structure of tricarbonyl[(1,2,3,4,5-η)-2-methoxy-2,4-cyclohexadien-1-yl]iron(1+) tetrafluoroborate, [Fe(C7H9O)(CO)3]BF4, is reported. Although the tetrafluoroborate salt crystallizes in a different space group to the previously reported hexafluorophosphate salt, the cations are isostructural.

Synthesis of novel L-phenylalanine derivatives substituted with a keto ylide as stable precursor of a vicinal tricarbonyl moiety

Novel L-phenylalanine derivatives 5 containing a vicinal tricarbonyl moiety at the para position of the phenyl ring were prepared in 4 steps starting from N α-Cbz-L-tyrosine benzyl ester. A 7 step reaction sequence lead to N α-Fmoc protected derivatives 9 with the tricarbonyl structure masked as its stable keto ylide precursor, which is suitable for solid phase peptide synthesis. The phosphoranylidene intermediates 8 were transformed to the trioxo compounds 5 with Oxone ® as oxidant

Tricarbonyl(η6-1-tetralol)chromium

In the structure of tricarbonyl(η 6 -1,2,3,4-tetrahydro-1-naphthalenol)chromium, [Cr(CO) 3 (C 10 H 12 O)], the group of three carbonyl ligands is syn with respect to the hydroxy group. The asymmetric unit contains two molecules of the same enantiomer with no significant differences in terms of intramolecular bond lengths and bond angles. The Cr(CO) 3 tripod is complexed to the benzene ring in an eclipsed conformation. An extensive hydrogen-bonding network supports the crystal structure.

Synthesis and characterization of tricarbonyl[ η6-(phenylethynyl)arene]chromium complexes: crystal structure of tricarbonyl[ η6-(3-phenylethynyl)anisole]chromium

Tricarbonyl( η 6-diphenylacetylene)chromium ( 4) was prepared from the reaction of tricarbonyl( η 6-fluorobenzene)chromium ( 3) with lithium phenylacetylide ( 2) at a low temperature using hexamethylphosphoric triamide as cosolvent. A concomitant tricarbonyl( η 6-butoxylbenzene)chromium ( 6) was also obtained in this reaction probably owing to both the air oxidation of n-BuLi and the ring opening of tetrahydrofuran by n-BuLi. The overwhelming abundance of meta and ortho products 9b and 10b produced in the substitution reaction of tricarbonyl( η 6-fluoroanisole)chromium ( 8a) by lithium phenylacetylide demonstrates that the reaction was by no means through the straightforward S NAr mechanism. The results provide support for the mechanism proposed by Pauson and Brookhart, in which the nucleophile attacked a carbon of the phenyl ring not bearing the leaving group, followed by hydrogen migration and finally elimination of the leaving group to achieve aromaticity. In addition, compounds were characterized by mass, IR, 1H and 13C NMR spectra, and elemental analysis. The molecular structure of tricarbonyl[ η 6-(3-phenylethynyl)anisole]chromium ( 9b) has been determined by X-ray diffraction studies. Crystal data are as follows: P 1; a = 7.782(2) A ̊ and c = 12.688(3) A ̊ ; α = 108.46(3)°, β = 96.05(3)° and γ = 103.19(3)°; V = 797.3(4) A ̊ 3; Z = 2; R = 3.23%; R w = 4.37% .

Tricarbonyl(η6-pyridine)chromium(0)

The molecular structure of tricarbonyl(η 6 -pyridine)chromium(0), [Cr(CO) 3 (C 5 H 5 N)], is presented here. The Cr atom is bound to the pyridine ring via the π-electron system and is situated directly below the heteroarene ring centre. The pyridine ring is slightly distorted compared to free pyridine and the distance from the Cr atom to the plane of the pyridine ring is 1.698 (2) A. The tricarbonyl moiety adopts an eclipsed conformation with respect to the pyridine ring atoms

Structure of tricarbonyl[(1,2,3,4,5,6-η)-N,N-diethyl-2-methoxy-4,5-dimethylbenzamide]chromium(0)

Structure of tricarbonyl[(1,2,3,4,5,6-η)-N,N-diethyl-2-methoxy-4,5-dimethylbenzamide]chromium(0)

Komplexierung von 1,3‐Dihydro‐1, 3, 10, 10‐tetramethyl‐1, 3‐dibora‐4, 5‐benzopentafulven mit Fe(CO)3‐ und CpCo‐Fragmenten: Synthese, Kristall‐ und Elektronenstruktur von Tricarbonyl[η5‐cyclopentadienyl)cobalt] [μ,η5:η4‐(1, 3‐dihydro‐1, 3, 10, 10‐tetramethyl‐1, 3‐dibora‐4, 5‐benzopentafulven)]eisen

Complexation of 1, 3‐Dihydro‐1, 3, 10, 10‐tetramethyl‐1, 3‐dibora‐4, 5‐benzopentafulvene with Fe(CO)3 and CpCo Fragments: Synthesis, Crystal and Electronic Structure of Tricarbonyl[(η5‐cyclopentadienyl)cobalt][μ,η5:η4‐(1, 3‐dihydro‐1, 3, 10, 10‐tetramethyl‐1, 3‐dibora‐4, 5‐benzopentafulvene)]ironReaction of the 1, 3‐dibora‐4, 5‐benzopentafulvene 1 with the isolobal organometallic fragments Co(C5H5) and Fe(CO)3 leads to the slipped triple‐decker complex 5. It is also formed when 2 is stacked with the Co(C5H5) fragment. The X‐ray structure analysis of 5 reveals that the Co(C5H5) fragment is coordinated to the 1, 3‐diborole ring, and the Fe(CO)3 group interacts with the Y‐shaped B2CC unit. An MO calculation indicates that the formation of 5 occurs by distortion of 2 (η5‐ → η4‐bonding) and complexation of the Co(C5H5) group. 5 is 16 kcal/mol more stable than its structural isomer 6.

ChemInform Abstract: Preparation and Characterization of 9,10‐Dihydroanthracene and tert.‐Butyl‐9,10‐dihydroanthracene Complexes with One or Two Tricarbonylchromium Units; Crystal Structure of Tricarbonyl (η1,2,3,4,4a,9a‐9,10‐dihydroanthracene)chromium.

AbstractThe η6‐dihydroanthracene(tricarbonyl‐Cr) compounds (IIIa) and (IIIb) are obtained by 1:1 molar reaction of corresponding 9,10‐dihydroanthracenes (I) with Cr(CO)6 (II) as shown.

ChemInform Abstract: The Structure of Tricarbonyl(styrene)chromium, a Crystal Active in Second‐Harmonic Generation

ChemInformVolume 20, Issue 47 Physical Organic Chemistry ChemInform Abstract: The Structure of Tricarbonyl(styrene)chromium, a Crystal Active in Second-Harmonic Generation G. M. BROWN, G. M. BROWN Chem. Div., Oak Ridge Natl. Lab., Oak Ridge, TN 37831, USASearch for more papers by this authorC. C. FRAZIER, C. C. FRAZIER Chem. Div., Oak Ridge Natl. Lab., Oak Ridge, TN 37831, USASearch for more papers by this author G. M. BROWN, G. M. BROWN Chem. Div., Oak Ridge Natl. Lab., Oak Ridge, TN 37831, USASearch for more papers by this authorC. C. FRAZIER, C. C. FRAZIER Chem. Div., Oak Ridge Natl. Lab., Oak Ridge, TN 37831, USASearch for more papers by this author First published: November 21, 1989 https://doi.org/10.1002/chin.198947047Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume20, Issue47November 21, 1989 RelatedInformation