Synthese der ersten quadratisch-planaren Vinyliden-Komplexe des Vaska-Typs. Kristall- und Molekülstruktur von trans-[RhCl(=C=CHMe)(PPri
 3)2] / Synthesis of the First Square-planar Vinylidene Complexes of the Vaska Type. Crystal and Molecular Structure of trans-[RhCl(=C=CHMe)(PPri
 3)2]

Werner, Helmut; Alonso, Francisco; Otto, H.; Wolf, Justin

doi:10.1515/znb-1988-0614

Cited by 86 publications

(5 citation statements)

References 6 publications

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“…When an isotope-labeled complex, Rh( 13 C⋮ 13 CC 6 H 5 )(nbd)[P(C 6 H 5 ) 3 ] 2 , was employed as an initiator, no 13 C-enriched polymeric products were obtained. This result indicates that the polymerization does not start via a direct insertion of PA s into either the rhodium−phenylethynyl bond or a vinylidenecarbene rhodium complex derived from 2 . The 1 H NMR spectrum of the oligomer ( M n = 2600, M w / M n = 1.10) obtained by polymerization of DC⋮CC 6 H 5 with 1 and DMAP in ether/methanol (2 equiv to DC⋮CC 6 H 5 ) gave no peaks due to olefinic protons at around δ 5.8, indicating methanol did not participate in the initiation step.…”

Section: Resultsmentioning

confidence: 96%

Well-Controlled Polymerization of Phenylacetylenes with Organorhodium(I) Complexes: Mechanism and Structure of the Polyenes

et al. 1999

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A tetracoordinate rhodium complex, Rh(C⋮CC6H5)(nbd)[P(C6H5)3] (nbd = 2,5-norbornadiene), combined with 4-(dimethylamino)pyridine (DMAP) is an excellent initiator for the stereospecific living polymerization of phenylacetylene and its m- and p-substituted derivatives. The rhodium initiator can be generated efficiently by dissociation of triphenylphosphine from isolable Rh(C⋮CC6H5)(nbd)[P(C6H5)3]2 or by reacting Rh(CH3)(nbd)[P(C6H5)3]2 or [Rh(OCH3)(nbd)]2/P(C6H5)3 with one equivalent of phenylacetylene. The use of a phenylethynyl group, triphenylphosphine, and NBD ligand attached to the rhodium center is crucial for the well-controlled polymerization of phenylacetylenes. An additive, DMAP, is necessary to attain low polydispersities of the polymer products. An active rhodium(I) complex bearing a growing polymer chain, NBD, and P(C6H5)3 was isolated from a reaction mixture and was characterized by NMR, GC−MS, XPS, and elemental analyses. The isolated active polymer initiates the further polymerization of the same monomer or substituted ones with an almost 100% initiation efficiency to give higher molecular weight homopolymers or block copolymers, respectively. Detailed NMR structural analysis of the products indicated that the polymerization with the rhodium(I) complexes proceeds via a 2,1-insertion mechanism to provide stereoregular poly(phenylacetylene)s with cis−transoidal backbone structure.

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Section: Resultsmentioning

confidence: 96%

Well-Controlled Polymerization of Phenylacetylenes with Organorhodium(I) Complexes: Mechanism and Structure of the Polyenes

et al. 1999

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“…Several methods have been employed for the preparation of mononuclear vinylidene complexes: from 1-alkynes via a formal 1,2-hydrogen shift, ,,− by addition of electrophiles to metal alkynyl complexes, − by deprotonation of carbyne complexes, , and by formal dehydration of acyl complexes. − In addition, alkenes, preformed vinyl complexes, and disubstituted alkynes have been used as precursors in a variety of transformations. ,− Transfer of vinylidene ligands between metal centers , and modification of existing vinylidene ligands ,, are reactions which also deserve further investigation.…”

Section: Mononuclear Half-sandwich Manganese Complexesmentioning

confidence: 99%

Metallacumulenes as Potential Electron Reservoir Devices

2006

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This paper reviews recent work in the area of organomanganese chemistry whose purpose is the design of single-molecule components for electronics. This field has recently received much attention in the pursuit of continued miniaturization of electronics. Electron reservoirs and molecular wires are basic motifs of single-electron devices. Both can accept and release electrons in a reversible fashion, but the former can also store electrons. Our recent work in the field deals with complexes of two distinct types: mononuclear half-sandwich manganese(I) vinylidene complexes, designed for application as electron reservoirs, and half-sandwich dinuclear manganese complexes and the bis-dmpe dinuclear MnII/MnII compounds, which were designed to serve as molecular wires. However, this review will focus on the mononuclear half-sandwich manganese(I) vinylidene and butatrienylidene systems, which have been synthetically successful systems and are supported by extensive DFT calculations and further detailed investigations using NMR, IR, UV−vis, and Raman spectroscopy, CV, magnetic susceptibilities, and X-ray diffraction studies.

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“…However, the mechanism of the reaction is still not completely understood. Recent experimental , and theoretical , studies suggest that the rearrangement may take place via different pathways, depending on the oxidation state of the metal and the type of ligands.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of the Acetylene−Vinylidene Rearrangement in the Coordination Sphere of a Transition Metal¹

Stegmann

Frenking

1998

Organometallics

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Quantum mechanical calculations at the CCSD(T) level of theory using BP86-optimized geometries indicate that the high-valent d0 tungsten acetylene complex [F2W(HCCH)] (1) is 10.4 kcal/mol lower in energy than the isomeric vinylidene complex [F4W(CCH2)] (2). Two energetically high-lying reaction pathways are calculated for the tautomerization reaction 1 → 2. The direct 1,2-hydrogen migration has a barrier of 84.8 kcal/mol and proceeds via the transition state TS1, which has a nonplanar C2H2 moiety. TS1 resembles the transition states for the rearrangement of the free C2H2 species in the triplet state and as an anion. The alternative rearrangement involves the alkynyl(hydrido) complex 3 as an intermediate, which is 50.5 kcal/mol higher in energy than 1. The rate-determining step of the two-step process 1 → 3 → 2 is the 1,3-hydrogen migration 3 → 2, which has an energy barrier of 85.5 kcal/mol with respect to 1. The high barriers for the two alternative pathways of the tautomerization reaction 1 → 2 make it unlikely that they play a role in the acetylene polymerization reaction, which is catalyzed by high-valent transition-metal compounds. The analysis of the bonding situation using the NBO and CDA methods show that 1 and 2 should not be considered as acetylene and vinylidene complexes but rather as metallacyclopropene and metallaallene, respectively.

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Synthese der ersten quadratisch-planaren Vinyliden-Komplexe des Vaska-Typs. Kristall- und Molekülstruktur von trans-[RhCl(=C=CHMe)(PPrⁱ ₃)₂] / Synthesis of the First Square-planar Vinylidene Complexes of the Vaska Type. Crystal and Molecular Structure of trans-[RhCl(=C=CHMe)(PPrⁱ ₃)₂]

Cited by 86 publications

References 6 publications

Well-Controlled Polymerization of Phenylacetylenes with Organorhodium(I) Complexes: Mechanism and Structure of the Polyenes

Well-Controlled Polymerization of Phenylacetylenes with Organorhodium(I) Complexes: Mechanism and Structure of the Polyenes

Metallacumulenes as Potential Electron Reservoir Devices

Mechanism of the Acetylene−Vinylidene Rearrangement in the Coordination Sphere of a Transition Metal¹

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Synthese der ersten quadratisch-planaren Vinyliden-Komplexe des Vaska-Typs. Kristall- und Molekülstruktur von trans-[RhCl(=C=CHMe)(PPri 3)2] / Synthesis of the First Square-planar Vinylidene Complexes of the Vaska Type. Crystal and Molecular Structure of trans-[RhCl(=C=CHMe)(PPri 3)2]

Cited by 86 publications

References 6 publications

Well-Controlled Polymerization of Phenylacetylenes with Organorhodium(I) Complexes: Mechanism and Structure of the Polyenes

Well-Controlled Polymerization of Phenylacetylenes with Organorhodium(I) Complexes: Mechanism and Structure of the Polyenes

Metallacumulenes as Potential Electron Reservoir Devices

Mechanism of the Acetylene−Vinylidene Rearrangement in the Coordination Sphere of a Transition Metal1

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Synthese der ersten quadratisch-planaren Vinyliden-Komplexe des Vaska-Typs. Kristall- und Molekülstruktur von trans-[RhCl(=C=CHMe)(PPrⁱ ₃)₂] / Synthesis of the First Square-planar Vinylidene Complexes of the Vaska Type. Crystal and Molecular Structure of trans-[RhCl(=C=CHMe)(PPrⁱ ₃)₂]

Mechanism of the Acetylene−Vinylidene Rearrangement in the Coordination Sphere of a Transition Metal¹