Übergangsmetallcarbin-komplexe

Fischer, Ernst Otto; Schambeck, W.; Kreißl, F. R.

doi:10.1016/s0022-328x(00)81165-1

Cited by 27 publications

(5 citation statements)

References 7 publications

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“…It was obtained as a byproduct (20% yield) from the reaction of diazoalkane with isocyanide, catalyzed by a copper complex. 46 The few known metal complexes containing σ-bonded keteneiminyl ligands result from the reaction of isocyanides with manganese and rhenium carbene complexes 47 or from insertion of a diazoalkane unit into a cobalt-isocyanide bond. 48 We did not observe analogous reactions when n BuNC and t BuNC were reacted with 1, with or without photolysis.…”

Section: Table 6 Selected Interatomic Distances Andmentioning

confidence: 99%

Transition Metal Diazoalkane Complexes. Synthesis, Structure, and Photochemistry of Rh[C(N₂)SiMe₃](PEt₃)₃

Deydier

Dartiguenave

et al. 1996

Organometallics

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Reaction of RhCl(PR3) n (R = Me (n = 4), Et (n = 3)) and RhCl(CO)(PEt3)2 with (trimethylsilyl)diazomethyl lithium at −78 °C in ether yields the three complexes Rh[C(N2)SiMe3](PEt3)3 (1), Rh[C(N2)SiMe3](PMe3)4 (2), and Rh[C(N2)SiMe3](CO)(PEt3)2 (3). 2 could not be isolated as a solid at room temperature but 1 was precipitated as red crystals that were stable enough to be handled under argon. X-ray work on 1 reveals a tetrahedrally distorted square-planar geometry with the planar (trimethylsilyl)diazomethyl ligand roughly perpendicular to the P3RhC coordination plane. This distortion makes the PEt3 ligands nonequivalent in the crystal and produces an ABB‘X pattern in the solid-state 31P NMR spectrum. Photolysis of Rh[C(N2)SiMe3](PEt3)3 leads quantitatively to the dimer [Rh{C(SiMe3)(PEt3)}(PEt3)2]2 (4). The presence of the two ylide bridges and terminal phosphines is deduced from the COSY 31P−31P NMR spectrum. This photochemical reactivity suggests that the transient carbene (PEt3)3RhC̈(SiMe3) is electrophilic, which is typical of a singlet carbene. We believe the singlet state is stabilized by the presence of the electron-rich low-spin Rh(PEt3)3 fragment. Reaction with nBuNC and tBuNC leads to stereo- and regioselective formation of a triazole that is σ bonded to the rhodium center. The X-ray structure of the tBuNC derivative Rh[CC(SiMe3)N2N t Bu]( t BuNC)2(PEt3) (5) shows a distorted square-planar geometry around Rh with the planar triazolato ligand roughly orthogonal to this plane. The probable reaction mechanism involves addition and substitution reactions of isocyanides at Rh followed by insertion into the Rh−C bond.

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Section: Table 6 Selected Interatomic Distances Andmentioning

confidence: 99%

Transition Metal Diazoalkane Complexes. Synthesis, Structure, and Photochemistry of Rh[C(N₂)SiMe₃](PEt₃)₃

Deydier

Dartiguenave

et al. 1996

Organometallics

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“…In particular, ketenimine complexes of transition metals have proven to be useful in new synthetic approaches to carbocyclic and four-, five-, and six-membered N-heterocyclic rings . Ketenimine complexes have been commonly prepared by C−C coupling reactions, for example by reacting carbene or carbyne complexes with isocyanides, but only in a few cases have they been prepared directly by coordination of free ketenimines .…”

Section: Introductionmentioning

confidence: 99%

Early-Transition-Metal Ketenimine Complexes: Synthesis, Reactivity, and Structure of Ketenimine-Containing Titanocene and Zirconocene Complexes

et al. 1997

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Reaction of Cp 2 M(PMe 3) 2 complexes (M = Ti, Zr; Cp = η 5-C 5 H 5) with the N-(p-tolyl)diphenylketenimine Ph´N=C=CPh 2 (Ph´ = p-MeC 6 H 4) in a 1:1 molar ratio affords the ketenimine-containing metallocene derivatives Cp 2 M(η 2-(C,N)-Ph´N=C=CPh 2)(PMe 3) (M = Ti (1); Zr (2)). The ketenimine ligand reacts in the same way with the "Cp* 2 M" species (Cp* = η 5-C 5 Me 5) generated from the reduction of the corresponding Cp* 2 MCl 2 complexes with Li t Bu (1:2 molar ratio) to give the related complexes Cp* 2 M(η 2-(C,N)-Ph´N=C=CPh 2) (M = Ti (3); Zr (4)). The molecular structure of 3 shows a titanium atom bonded to two η 5-cyclopentadienyl rings and a η 2-(C,N)-bonded ketenimine ligand. Reaction of "Cp* 2 Ti" with the ketenimine ligand in a 1:2 molar ratio gives 1,1,5,5-tetraphenyl-3-(p-tolyl)-2-(ptoluidino)-3-aza-1,4-pentadiene, which probably results from the coupling, followed by hydrolysis, of two ketenimine molecules coordinated to one titanocene moiety. Protonation of 3 with Et 3 NHCl or H 2 O (1:1 molar ratio) affords the intermediate species Cp* 2 Ti(X)(η 2-(C,N)-Ph´N-C(H)-CPh 2) (X = Cl (5); OH (6)), which on hydrolysis evolves to give the enamine Ph´N(H)-CH=CPh 2 as the final product. Finally, 3 reacts reversibly with H 2 to give the hydride enamidate complex Cp* 2 Ti(H)(η 1-Ph´N-CH=CPh 2) (7). The structures of the different compounds have been determined by IR and NMR spectroscopic methods.

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“…An example is the complex [N(Et) 4 ] [Cl 4 W(CtBu)] À . [33] Unfortunately no experimental geometries of negatively charged carbyne complexes are known to us. [a] Tilting angle of the amino group, see Figure 1.…”

mentioning

confidence: 99%

Structure and Bonding of Low‐Valent (Fischer‐Type) and High‐Valent (Schrock‐Type) Transition Metal Carbyne Complexes

Vyboishchikov

Frenking

1998

Chemistry A European J

101

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Quantum mechanical ab initio calculations are reported for 13 lowvalent (Fischer-type) and 13 high-valent (Schrock-type) tungsten carbyne complexes. The geometries have been optimized at the HF and MP2 levels of theory with relativistic effective core potentials for the heavy atoms with valence basis sets of DZP quality. Tungsten ± carbyne bond dissociation energies are predicted at CCSD(T) with MP2 optimized geometries. The electronic structure of the complexes and the metal ± ligand bonding have been analyzed with the help of the NBO method, the topological analysis of the electron-density distribution and the CDA method. The L n W ± CR bonds of the Fischer and Schrock carbyne complexes are much stronger than those of related carbene complexes. The strength of the L n W ± CR bond is strongly influenced by the nature of R.

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Übergangsmetallcarbin-komplexe

Cited by 27 publications

References 7 publications

Transition Metal Diazoalkane Complexes. Synthesis, Structure, and Photochemistry of Rh[C(N₂)SiMe₃](PEt₃)₃

Transition Metal Diazoalkane Complexes. Synthesis, Structure, and Photochemistry of Rh[C(N₂)SiMe₃](PEt₃)₃

Early-Transition-Metal Ketenimine Complexes: Synthesis, Reactivity, and Structure of Ketenimine-Containing Titanocene and Zirconocene Complexes

Structure and Bonding of Low‐Valent (Fischer‐Type) and High‐Valent (Schrock‐Type) Transition Metal Carbyne Complexes

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Übergangsmetallcarbin-komplexe

Cited by 27 publications

References 7 publications

Transition Metal Diazoalkane Complexes. Synthesis, Structure, and Photochemistry of Rh[C(N2)SiMe3](PEt3)3

Transition Metal Diazoalkane Complexes. Synthesis, Structure, and Photochemistry of Rh[C(N2)SiMe3](PEt3)3

Early-Transition-Metal Ketenimine Complexes: Synthesis, Reactivity, and Structure of Ketenimine-Containing Titanocene and Zirconocene Complexes

Structure and Bonding of Low‐Valent (Fischer‐Type) and High‐Valent (Schrock‐Type) Transition Metal Carbyne Complexes

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Transition Metal Diazoalkane Complexes. Synthesis, Structure, and Photochemistry of Rh[C(N₂)SiMe₃](PEt₃)₃

Transition Metal Diazoalkane Complexes. Synthesis, Structure, and Photochemistry of Rh[C(N₂)SiMe₃](PEt₃)₃