Insights into the Molecular Structure and Reactivity of α,ω‐Dialkoxy‐Substituted Ethyne and Butadiyne

Gleiter, Rolf; Werz, Daniel B.; Röminger, Frank; Zhutov, E. V.; Зефиров, Н. С.; Проскурнина, М. В.

doi:10.1002/ejoc.200700617

Cited by 10 publications

(8 citation statements)

References 39 publications

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“…The Si−O distance is 1.674(2) Å, consistent with Si−O distances of structurally related RMe 2 Si−O−CN and other terminal siloxycarbyne metal complexes, , and the ∠C−O−Si angle is 155.0(2)°. The 1.278(3) Å C−O bond distance can be compared to C−O single bonds in the few structurally characterized organic alkynyl ether molecules with a CC−O−X-type linkage . Stang has, for example, structurally determined that the acetylenic−oxygen C(sp)−O bond distance in −CC−O−SO 2 R-type derivatives is far shorter (ca.…”

Section: Resultsmentioning

confidence: 99%

Silylation of Iron-Bound Carbon Monoxide Affords a Terminal Fe Carbyne

2011

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A series of monocarbonyl iron complexes in the formal oxidation states 0, þ1, and þ2 are accessible when supported by a tetradentate tris(phosphino)silyl ligand (SiP iPr 3 = [Si(o-C 6 H 4 PiPr 2 ) 3 ] -). X-ray diffraction (XRD) studies of these carbonyl complexes establish little geometrical change about the iron center as a function of oxidation state. It is possible to functionalize the terminal CO ligand of the most reduced carbonyl adduct by addition of SiMe 3 þ to afford a welldefined iron carbyne species, (SiP iPr 3 )FetC-OSiMe 3 . Single-crystal XRD data of this iron carbyne derivative reveal an unusually short FetC-OSiMe 3 bond distance (1.671(2) Å) and a substantially elongated C-O distance (1.278(3) Å), consistent with Fe-C carbyne character. The overall trigonal bipyramidal geometry of (SiP iPr3 )FetC-OSiMe 3 compares well with that of the corresponding carbonyls, (SiP iPr 3 )Fe(CO) -, (SiP iPr 3 )Fe(CO), and (SiP iPr 3 )Fe(CO) þ . Details regarding the electronic structure of the carbyne complex have been explored via the collection of comparative M€ ossbauer data for all of the complexes featured and also via DFT calculations. In sum, these data point to a strongly π-accepting Fischer-type carbyne ligand that confers stability to a lowvalent iron(0) rather than high-valent iron(IV) center.

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Section: Resultsmentioning

confidence: 99%

Silylation of Iron-Bound Carbon Monoxide Affords a Terminal Fe Carbyne

2011

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“…The most stable 1,4-bis(alkoxy)-1,3-butadiynes were those with the bulky adamantyl- and t -butoxy substituents . The latter was also crystallographically characterized …”

Section: Alkynes Substituted By Elements Of Main Groups V−viiimentioning

confidence: 99%

Alkynes Between Main Group Elements: From Dumbbells via Rods to Squares and Tubes

Gleiter

Werz

2010

Chem. Rev.

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Introduction 4447 2. Alkynes Substituted by Elements of Main Groups I-IV (Except Carbon) 4449 2.1. Alkynes Substituted by Elements of Main Groups I and II 4449 2.1.1. Alkali and Alkali Earth Metal Derivatives of Alkynes 4449 2.1.2. Alkali and Alkali Earth Metal Carbides 4450 2.1.3. Quantum Chemical Calculations on the Metal-Alkyne Interaction of Group II Metals 4451 2.2. Alkynes Substituted by Elements of Main Group III 4451 2.

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“…[25] Furthermore, the O2 À C24 bond (1.291 (2) ) is considerably longer than that of the terminal carbonyl www.chemeurj.org ligand (O1 À C23 1.178(2) ) and close in length to the C sp À O single bonds of alkoxyalkynes (e.g., 1.303(1) in tBuO À A C H T U N G T R E N N U N G (C C) 2 À OtBu). [26] The elongated Si À O bond of 5 (1.749(1) ) relative to those of alkoxysilanes (1.642 ), [27] complements the bonding picture of a siloxycarbyne complex with some m-isocarbonyl character. This is further confirmed by the short CrÀSi distance (2.2847(6) ) lying between those of Cr=Si double bonds (e.g., 2.161 in 3-Cl and 3-Br) and Cr À Si single bonds (2.399 ).…”

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confidence: 95%

ChromiumSilicon Multiple Bonds: The Chemistry of Terminal N‐Heterocyclic‐Carbene‐Stabilized Halosilylidyne Ligands

Filippou

Chernov

Schnakenburg

2011

Chemistry A European J

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An efficient method for the synthesis of the first N-heterocyclic carbene (NHC)-stabilized halosilylidyne complexes is reported that starts from SiBr(4). In the first step, SiBr(4) was treated with one equivalent of the N-heterocyclic carbene 1,3-bis[2,6-bis(isopropyl)phenyl]imidazolidin-2-ylidene (SIdipp) to give the 4,5-dihydroimidazolium salt [SiBr(3)(SIdipp)]Br (1-Br), which then was reduced with potassium graphite to afford the silicon(II) dibromide-NHC adduct SiBr(2)(SIdipp)(2-Br) in good yields. Heating 2-Br with Li[CpCr(CO)(3)] afforded the complex [Cp(CO)(2)Cr=SiBr(SIdipp)] (3-Br) upon elimination of CO. Complex 3-Br features a trigonal-planar-coordinated silicon center and a very short CrSi double bond. Similarly, the reaction of SiCl(2)(SIdipp) (2-Cl) with Li[CpCr(CO)(3)] gave the analogous chloro derivative [Cp(CO)(2)Cr=SiCl(SIdipp)] (3-Cl). Complex 3-Br undergoes an NHC exchange with 1,3-dihydro-4,5-dimethyl-1,3-bis(isopropyl)-2H-imidazol-2-ylidene (IMe(2)iPr(2)) to give the complex [Cp(CO)(2)CrSiBr(IMe(2)iPr(2))(2)] (4-Br). Compound 4-Br features a distorted-tetrahedral four-coordinate silicon center. Bromide abstraction occurs readily from 4-Br with Li[B(C(6)F(5))(4)] to give the putative silylidene complex salt [Cp(CO)(2)Cr=Si(IMe(2)iPr(2))(2)][B(C(6)F(5))(4)], which irreversibly dimerizes by means of an Si-promoted electrophilic activation of one carbonyl oxygen atom to yield the dinuclear siloxycarbyne complex [Cp(CO)Cr{(μ-CO)Si(IMe(2)iPr(2))(2)}(2-)Cr(CO)Cp][B(C(6)F(5))(4)](2) (5). All compounds were fully characterized, and the molecular structures of 2-Br-5-Br were determined by single-crystal X-ray diffraction. DFT calculations of 3-Br and 3-Cl and their carbene dissociation products [Cp(CO)(2)Cr=Si-X] (X=Cl, Br) were carried out, and the electronic structures of 3-Br, 3-Cl and [Cp(CO)(2)Cr=Si-X] were analyzed by the natural bond orbital method in combination with natural resonance theory.

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Insights into the Molecular Structure and Reactivity of α,ω‐Dialkoxy‐Substituted Ethyne and Butadiyne

Cited by 10 publications

References 39 publications

Silylation of Iron-Bound Carbon Monoxide Affords a Terminal Fe Carbyne

Silylation of Iron-Bound Carbon Monoxide Affords a Terminal Fe Carbyne

Alkynes Between Main Group Elements: From Dumbbells via Rods to Squares and Tubes

ChromiumSilicon Multiple Bonds: The Chemistry of Terminal N‐Heterocyclic‐Carbene‐Stabilized Halosilylidyne Ligands

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