Synthesis and reactivity of dicobalt stabilised but-2-yne-1,4-dicarbenium ions

Bennett, Stephen C.; Phipps, Mark A.; Went, Michael J.

doi:10.1039/c39940000225

Cited by 15 publications

(7 citation statements)

References 5 publications

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“…Further, we note that the carbenium centers in complex 5 are stabilized by the molybdenum centers (Mo−CH 2 + ) and not the cobalt atoms; this is not a surprising result; previously, we have reported several X-ray structures of heterobimetallic chiral [Mo−Co] propargylium complexes, which show that the carbenium center (−CH 2 + ) is bent toward the molybdenum rather than the cobalt; this deformation is a clear indication that the molybdenum atom is alleviating the electron deficiency at the α-carbon center . We also note that Went et al suggested the formation of a bridged thioether tetranuclear alkyne complex of cobalt …”

Section: Resultssupporting

confidence: 58%

“…The difference in reactivity between the Cp system and that of the Fv analogue was attributed to the rigid nature of the fulvalene ligand. Finally, we note that Went et al reported the formation of the dicarbenium cobalt complex [Co 2 (CO) 4 L 2 (μ-η 3 ,η 3 -CH 2 −C⋮C−CH 2 ][BF 4 ] 2 (L = CO, Ph 2 PCH 2 PPh 2 ), and its reactivity was also investigated . However the dicarbenium complex was not isolated.…”

Section: Introductionmentioning

confidence: 92%

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A General Route to Prochiral and Chiral Dicationic Molybdenum−Cobalt Acetylenic Complexes: Synthesis, Structures, and Reactivity

et al. 1998

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Several [Co−Co]−alkyne adducts [Co2(CO)6)(μ-η2,η2-HOCR1R2-C⋮C−CR1R2OH)] were prepared (R1 = R2 = H (1); R1 = H, R2 = CH3 (2); R1 = R2 = CH3 (3)) and their X-ray molecular structures determined, showing that the μ-alkyne unit adopts a specific geometry depending on the nature of the alkyne unit. The prochiral [Mo−Co]−alkyne adduct [CpMoCo(CO)5(μ-η2,η2-HOCH2−C⋮C−CH2OH)] (4), identified by X-ray analysis, was obtained from [Co2(CO)6)(μ-η2,η2-HOCH2−C⋮C−CH2OH)] (1) via replacement of a −Co(CO)3 vertex by the isolobal moiety −CpMo(CO)2. Complex 4 reacts with aqueous HBF4 to produce the dicationic tetranuclear species [{CpMoCo(CO)5(μ-η2,η3-CH2−C⋮C−CH2-)}2O][BF4]2 (5), which reacts further with nucleophiles to give a new dicationic tetranuclear species [{CpMoCo(CO)5(μ-η2,η2-Nu1−CH2−C⋮C−CH2−)}2O][BF4]2 (Nu1 = pyridine (6), 3-picoline (7), triphenylphosphine (8)), where the nucleophile has been introduced to the carbenium center (−CH2 +). Subsequent treatment of these dications in acidic medium produces the carbenium ions [CpMoCo(CO)5(μ-η2,η3-Nu1−CH2−C⋮C−CH2)][BF4]2 (Nu1 = pyridine (9), 3-picoline (10), triphenylphosphine (11)), which further react with nucleophile Nu2 to produce dications [CpMoCo(CO)5(μ-η2,η2-Nu1−CH2−C⋮C−CH2−Nu2)][BF4]2 {Nu1 = Nu2 = pyridine (13); Nu1 = pyridine, Nu2 = triphenylphosphine (14); Nu1 = Nu2 = triphenylphosphine (15); Nu1 = Nu2 = 3-picoline (16); Nu1 = pyridine = Nu2 = 3-picoline (17)). This synthetic approach is unprecedented because it allows the placement of the same or different types of nucleophiles in a stepwise fashion at the two terminal carbon atoms of the acetylenic complex, yielding, for instance, the chiral dicationic [Mo−Co] cluster [CpMoCo(CO)5(μ-η2,η2-C6H5N−CH2−C⋮C−CH2−NC6H4(CH3))][BF4]2 (17). The X-ray molecular structures of 13, 16, and 17 belonging to this family were determined, including the first chiral [Mo−Co] complex (17) possessing two different functional groups. Further, the structure shows that the coordinated functionalized alkyne can adopt a specific geometry, whereby the two positively functionalized groups are situated on the same side of the cluster unit, available to bind molecules of opposite charge.

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Section: Resultssupporting

confidence: 58%

Section: Introductionmentioning

confidence: 92%

A General Route to Prochiral and Chiral Dicationic Molybdenum−Cobalt Acetylenic Complexes: Synthesis, Structures, and Reactivity

et al. 1998

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“…2+ Indeed the dicarbenium fulvalene complex reacts with weak nucleophiles to give the corresponding monocarbenium derivatives, while with strong nucleophiles double nucleophilic additions to both carbenium centers were observed. 59b Other dicationic species were described in the literature 60 one of them possesses a ferrocenyl function between the two carbenium centers. 61…”

Section: Identification and Physical Characteristicsmentioning

confidence: 99%

“…The pyridinium 73 and the phosphonium complexes 74ab are less reactive. Went and co-workers, , have studied the reaction of thiols with dicationic [Co 2 ]−propargyl compounds prepared in situ. The authors observed the formation of mono- and disubstituted thioether complexes depending on the amount of thiol used.…”

Section: Reactivitymentioning

confidence: 99%

New Bonding Modes, Fluxional Behavior, and Reactivity in Dinuclear Complexes Bridged by Four-Electron Donor Unsaturated Hydrocarbons

1996

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“…This behavior is completely different from that displayed by analogous dicarbenium complexes coordinated to Co 2 (CO) 6 and/or Cp 2 Mo 2 (CO) 4 moieties. In the latter systems nucleophilic attacks occur simultaneously on both carbenium centers …”

Section: Resultsmentioning

confidence: 99%

Reactions of a Dicarbenium Fulvalenyl Complex with Aromatic Nucleophiles and Synthesis of (μ-Alkyne)(fulvalenyl)tetracarbonyldimolybdenum Compounds: A Structure−Reactivity Relationship

et al. 1997

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The compound [FvMo2(CO)4(μ-η3:η3-CH2C⋮CCH2)][BF4]2 (3) reacts with weak nucleophiles to give the related carbenium complexes [FvMo2(CO)4(μ-η2:η3-CH2C⋮CCH2Nu)][BF4] (Nu = −C6H4OH, −C6H4OMe), where attack occurs exclusively on one carbenium center (−CH2 +). Subsequent treatment by NaBH4 reduces the second carbenium center (−CH2 +) to yield the disubstituted alkyne fulvalenyl adducts. The difference in reactivity between 3 and the analogous dicarbenium Cp system [Cp2Mo2(CO)4(μ-η3:η3-CH2C⋮CCH2)][BF4]2 is attributed to the fulvalene effect.

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Synthesis and reactivity of dicobalt stabilised but-2-yne-1,4-dicarbenium ions

Cited by 15 publications

References 5 publications

A General Route to Prochiral and Chiral Dicationic Molybdenum−Cobalt Acetylenic Complexes: Synthesis, Structures, and Reactivity

A General Route to Prochiral and Chiral Dicationic Molybdenum−Cobalt Acetylenic Complexes: Synthesis, Structures, and Reactivity

New Bonding Modes, Fluxional Behavior, and Reactivity in Dinuclear Complexes Bridged by Four-Electron Donor Unsaturated Hydrocarbons

Reactions of a Dicarbenium Fulvalenyl Complex with Aromatic Nucleophiles and Synthesis of (μ-Alkyne)(fulvalenyl)tetracarbonyldimolybdenum Compounds: A Structure−Reactivity Relationship

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