Chiral Tungsten(II) .eta.1-Ketone and .eta.1-Aldehyde Complexes

Caldarelli, Jennifer L.; Wagner, Laura E.; White, Peter S.; Templeton, Joseph L.

doi:10.1021/ja00086a021

Cited by 31 publications

(35 citation statements)

References 1 publication

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“…This situation leads to the heat evolution in the syntheses of the complexes under study and apparently to the thermodynamic feasibility of the formation of products with higher hapticity of the heterodiene coordination. The reliability of the calculated bond energies is confirmed by the agreement of the calculated values with the published data on the bond strength metalcarbon monoxide in the hexacarbonyl complexes of the chromium subgroup metals [9]. Table 1.…”

Section: And2supporting

confidence: 70%

Synthesis of Mesityl Oxide π-Complexes with Metals of Chromium Subgroup and with Iron. Theoretical and Experimental Investigation of the Ligand Dissociation Energy

2005

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At the use of photochemical and thermochemical activation new p-complexes of chromium, molybdenum, and tungsten were prepared containing in the coordination sphere h 2 -and h 4 -molecules of 4-methyl-3-penten-2-one. Nonempirical methods were applied to calculation of the energy parameters of the coordinated molecules, and the factors governing the h 2 -and h 4 -coordination of the oxodiene system were established. A thermochemical study was performed on the 4-methyl-3-penten-2-one h 4 -coordination product with carbonyl metal core. A scheme of the thermal decomposition was suggested for the iron (0) h 4 -(4-methyl-3-penten-2-one)tricarbonyl.A development of new preparative procedures based on the chemo-, regio-, and stereoselective addition reactions is among the most prominent trends in the modern synthetic chemistry. The interest attracted by this field of the synthetic organic and organometallic chemistry originates from the maximum atomic efficiency and atom-saving [1] of the addition reactions, especially of those occurring strictly at the definite structural fragments of substrates.We showed formerly that conjugated oxo-and azadienes located in the coordination sphere of the transition metals were involved in dialkyl phosphines addition at the carbon-heteroatom double bond irrespective of the type of heterodiene coordination with the metal center [26].The equal reactivity of the coordinated heterodienes independent of hapticity of their bonding cannot be rationalized regarding the metal only as a protective group [36] since as we have established the bonding with the metal center results in significant changes in the geometry and electronic structure of the oxodiene ligand [7]. Obviously for successful intracomplex functionalizing of unsaturated molecules a detailed study is required on the factors governing the readiness of organometallic compounds formation and also on the thermal stability and reactivity of the unsaturated molecules within the coordination sphere of the transition metal.In the present study we approached these problems by investigation of reactions between the 4-methyl-3-penten-2-one (mesityl oxide) and iron(0) pentacarbonyl and hexacarbonyls of metals of VIB group under both photochemical and thermochemical activation.Under UV irradiation of a THF solution containing a homocarbonyl complex of a transition metal and mesityl oxide products were obtained of h 2 -coordination of aenone IaId. The p-type coordination of the olefin ligand with the metal atom was confirmed by the appearance in the IR spectra of the reaction products of the absorption bands of the C=C bond coordinated to a metal center: 1560 (Ia), 1565 cm 1 (Id); in a free mesityl oxide the corresponding band was observed at 1640 cm 1 . In the region of the stretching vibrations of the C=O bond of the carbonyl ligands coordinated to the metal in the spectrum of compound Ia were observed four, and in the spectra of compounds Ib-Id five well resolved bands revealing that only one molecule of carbon monoxide was replaced in...

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Section: And2supporting

confidence: 70%

Synthesis of Mesityl Oxide π-Complexes with Metals of Chromium Subgroup and with Iron. Theoretical and Experimental Investigation of the Ligand Dissociation Energy

2005

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“…Analogous examples were described in [14][15][16] where complex formation of Schiff bases with iron and chromium subgroup metals was studied. Analogous examples were described in [14][15][16] where complex formation of Schiff bases with iron and chromium subgroup metals was studied.…”

Section: IIImentioning

confidence: 95%

“…Another possible reason for formation of α-aminophosphonate IV in the base-catalyzed hydrophosphorylation of complex IIc is that triethylamine coordinates to the metal, thus displacing the imino nitrogen atom from the coordination sphere of transition metal [15]. The resulting complex is like η 2 -[(C=C)azadiene]tetracarbonyl(triethylamine)metal(0) in which the C=N bond is sensitive to nucleophilic attack.…”

Section: IIImentioning

confidence: 99%

Synthesis, structure, and hydrophosphorylation of ?-complexes derived from tert-butyl(1,3-dimethyl-2- butenylidene)amine and homoligand iron(0) and group VIb metal carbonyls

2004

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New iron(0), chromium(0), molybdenum(0), and tungsten(0) π-complexes containing η 2 -, η 3 -, and η 4 -coordinated tert-butyl(1,3-dimethyl-2-butenylidene)amine ligands were synthesized under conditions of photochemical and thermal activation. The geometric, electronic, and energetic parameters of the coordinated 1,3-azadiene were calculated by nonempirical methods, and factors determining the mode of coordination were established. The obtained π-complexes reacted with dialkyl phosphonates in the presence of triethylamine to afford organometallic α-aminophosphonates; hydrophosphorylation in the absence of a catalyst gave the corresponding amidophosphate which then underwent rearrangement into α-aminophosphonate.

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“…In the presence of excess ethylene (−78 °C), Tp(CO)(PhC⋮CPh)W−Me (2) was treated with HBAr 4 ‘ (BAr 4 ‘ = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate). Elimination of methane should generate an open coordination site suitable for binding ethylene (eq 2). The result was the formation of a complex which exhibited a CO stretching frequency at 2043 cm -1…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Reactivity of Tungsten(II) Methylene Complexes

et al. 1997

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Treatment of the methyl complex Tp′(CO)(PhC 2 Me)W-Me (1) or Tp(CO)(PhC 2 Ph)W-Me (2) with trityl cation yields the corresponding methylene complex [Tp′(CO)(PhC 2 Me)WdCH 2 ]-[PF 6 ] (3) (Tp′ ) hydridotris-(3,5-dimethylpyrazolyl)borate) or [Tp(CO)(PhC 2 Ph)WdCH 2 ][PF 6 ] (4) (Tp ) hydridotris(pyrazolyl)borate). The carbene complex (3) is unusually persistent for a methylene complex. Complexes 3 and 4 display electrophilic behavior, as evidenced both by addition of nucleophiles and by methylene transfer to electron rich olefins. When bound to either carbene 3 or 4, arylimines are activated toward nucleophilic attack by ethyl diazoacetate (EDA). The net result of the addition of excess arylimine followed by excess EDA to a solution of either 3 or 4 is catalytic aziridine formation. X-ray diffraction studies have revealed the structures of [Tp′(CO)(PhC 2 Me)W-CH 2 PMe 3 ][PF 6 ] (7) and [Tp′(CO)(PhC 2 -Me)W-CH 2 N(Me)dC(H)(Ph)][PF 6 ] (15). The relative stabilities of 3 and 4 are discussed as well as the mechanism of aziridine catalysis.

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Chiral Tungsten(II) .eta.1-Ketone and .eta.1-Aldehyde Complexes

Cited by 31 publications

References 1 publication

Synthesis of Mesityl Oxide π-Complexes with Metals of Chromium Subgroup and with Iron. Theoretical and Experimental Investigation of the Ligand Dissociation Energy

Synthesis of Mesityl Oxide π-Complexes with Metals of Chromium Subgroup and with Iron. Theoretical and Experimental Investigation of the Ligand Dissociation Energy

Synthesis, structure, and hydrophosphorylation of ?-complexes derived from tert-butyl(1,3-dimethyl-2- butenylidene)amine and homoligand iron(0) and group VIb metal carbonyls

Synthesis and Reactivity of Tungsten(II) Methylene Complexes

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