Metallorganische Lewissäuren

Milke, Jasna; Missling, Christopher U.; Sünkel, Karlheinz; Beck, Wolfgang

doi:10.1016/0022-328x(93)80209-t

Cited by 18 publications

(10 citation statements)

References 60 publications

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“…We succeeded in synthesizing related cationic hydroxycyclopentadienyl ruthenium alcohol complexes,vi which dissociate alcohol rapidly at low temperature. Very few alcohol complexes have been crystallographically characterized;iiia,iiie,vii all of the structurally characterized alcohol complexes are cationic compounds.…”

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Cyclopentadienone Iron Alcohol Complexes: Synthesis, Reactivity, and Implications for the Mechanism of Iron-Catalyzed Hydrogenation of Aldehydes

2009

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Cyclopentadienone iron alcohol complexes generated from the reactions of [2,5-(SiMe 3 ) 2 -3,4-(CH 2 ) 4 (η 5 -C 4 COH)]Fe(CO) 2 H (3) and aldehydes were characterized by 1 H NMR, 13 C NMR, and IR spectroscopy. The benzyl alcohol complex [2,5-(SiMe 3 ) 2 -3,4-(CH 2 ) 4 (η 5 -C 4 C=O)]Fe (CO) 2 (HOCH 2 C 6 H 5 ) (6-H) was also characterized by X-ray crystallography. These alcohol complexes are thermally unstable and prone to dissociate the coordinated alcohols. The alcohol ligand is easily replaced by other ligands such as PhCN, pyridine, and PPh 3 . Dissociation of the alcohol ligand in the presence of H 2 leads to the formation of iron hydride 3. The reduction of aldehydes by 3 was carried out in the presence of both potential intermolecular and intramolecular traps. The reaction of 3 with PhCHO in the presence of 4-methylbenzyl alcohol as a potential intermolecular trapping agent initially produced only iron complex 6-H of the newly formed benzyl alcohol. However, the reaction of 3 with 4-(HOCD 2 )C 6 H 4 CHO (11-d 2 ), which possesses a potential intramolecular alcohol trapping agent, afforded two alcohol complexes, one with the newly formed alcohol coordinated to iron and the other with the trapping alcohol coordinated. The intramolecular trapping experiments support a mechanism involving concerted transfer of a proton from OH and hydride from Fe of 3 to aldehydes. The kinetics and mechanism of the hydrogenation of benzaldehyde catalyzed by 3 are presented.Alcohol complexes play important roles in transition metal catalyzed reactions. They serve as catalyst precursors by dissociating the alcohol ligand and creating vacant coordination sites for substrate binding. They have been proposed as essential intermediates in aerobic alcohol oxidations, i silane alcoholysis, ii and ionic hydrogenation of carbonyl groups. iii Alcohol complexes have been suggested as possible intermediates in the hydrogenation of ketones and aldehydes catalyzed by Shvo's diruthenium hydride complex 1-S iv and its tolyl analog 1. However, all attempts to prepare or spectroscopically observe these ruthenium alcohol complexes have been unsuccessful. v We succeeded in synthesizing related cationic hydroxycyclopentadienyl ruthenium alcohol complexes, vi which dissociate alcohol rapidly at low temperature. Very few alcohol complexes have been crystallographically characterized; iiia,iiie,vii all of the structurally characterized alcohol complexes are cationic compounds.Ligand-metal bifunctional hydrogenation catalysis is dramatically changing the face of reduction chemistry. viii These transition metal catalysts contain electronically coupled casey@chem.wisc.edu. Supporting Information Available: General experimental information, experimental procedures, synthesis of alcohol complexes, rates of substitution of coordinated alcohols by PhCN, rates of hydrogenation of aldehydes catalyzed by 3, X-ray crystallographic data for {2,5-(SiMe 3 ) 2 -3,4-[(CH 2 ) 4 ](η 4 -C 4 CO)}Fe(CO) 2 (HOCH 2 Ph) (6-H). This material is available free of cha...

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Cyclopentadienone Iron Alcohol Complexes: Synthesis, Reactivity, and Implications for the Mechanism of Iron-Catalyzed Hydrogenation of Aldehydes

2009

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“…Using a chiral neomenthyl substituent on the cyclopentadienyl ring allowed the separation of the chiral‐at‐metal MeCN complexes . Nitriles used in these reactions include MeCN, olefinic and aromatic nitriles as well as cyanoacetic methylester , , . Quite interesting, it was not successful to obtain the corresponding Ru complex with the long chain nitrile C 18 H 37 CN by this method, whereas the reaction of the more electron rich [CpRu(P R 3 ) 2 Cl] proceeded without difficulty .…”

Section: Resultsmentioning

confidence: 99%

“…[21] Nitriles used in these reactions include MeCN, olefinic and aromatic nitriles as well as cyanoacetic methylester. [5,22,23] Quite interesting, it was not successful to obtain the corresponding Ru complex with the long chain nitrile C 18 H 37 CN by this method, whereas the reaction of the more electron rich [CpRu(PR 3 ) 2 Cl] proceeded without difficulty. [14] A rather unusual synthesis of [CpFe(CO)(PPh 3 )(MeCN)] + used the reaction of the vinylidene complex [CpFe(CO)(PPh 3 )(=C=CH 2 )] + with hydrazine derivatives.…”

Section: Resultsmentioning

confidence: 99%

“…Chiral complexes of iron and ruthenium with four different ligands Cp M (CO)(PR 3 ) X and [Cp M (CO)(PR 3 )(L)] + ( M = Fe, Ru) and the Gladysz complexes [CpRe(NO)(PPh 3 )(L)] +[7] have found high attention as inorganic counter parts of methane derivatives and very many examples have been reported. Brunner was the first to accomplish chiral resolution of organometallic complexes with four different ligands .…”

Section: Introductionmentioning

confidence: 99%

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Organometallic Lewis Acids, Part LXII. Chiral Carbonyl‐Cyclopentadienyl‐Triphenylphosphine‐Iron and ‐Ruthenium Complexes with Tertiary Nitriles [CpM(CO)(PPh₃)(N≡C–CR¹R²R³)]⁺ BF₄^– (M = Fe, Ru)

Missling

Sünkel

Langhals

et al. 2017

Zeitschrift anorg allge chemie

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A series of tertiary nitriles was synthesized by alkylation of acetonitrile, primary and secondary nitriles, using alkylbromides and sodium amide in liquid ammonia. By reaction of the in situ formed organometallic Lewis acids [CpM(CO)(PPh3)]+ (M = Fe, Ru) with the novel tertiary nitriles, the complexes [CpM(CO)(PPh3)(N≡C–CR1R2R3]BF4 were obtained. A di‐iron complex was formed with 1,6‐dicyanohexane.

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“…Quite stable organometallic adducts of carboxylic acid esters( 1 ) were obtained with the strong cationic Lewis acids[CpFe(CO) 2 ] + [13, 14], [HC(py) 3 M(NO) 2 ] 2+ ( M = Mo, W 15,[CpRe(NO)(PPh 3 )] + 16, [Re(CO) 5 ] + 17 and [CpRu(CO)(PPh 3 )] + 17.…”

Section: Esters As Ligandsmentioning

confidence: 99%

Coordination of the Ester Group – Hydrido‐Rhodium(III) and Iridium(III) Complexes of Orthometallated Diphenylmethylene Glycine Esters [1]

Schreiner

Beck

2010

Zeitschrift anorg allge chemie

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An overview on metal complexes that contain coordinated ester groups is given. A new example has been obtained by oxidative addition of the O′Donnell reagent Ph2C=NCH2CO2R to [(cyclooctene)2MCl]2 (M = Rh, Ir) which – in the presence of tricyclohexylphosphine – affords the complexes {(H)(Cl)[C6H11)3P]2M(C6H4)C(Ph)=NCH2CO2R}. In these complexes, the chlorido ligand is replaced for the ester group by using AgPF6 to give {(H)[(C6H11)3P]2M[C6H4)C(Ph)=NCH2CO2R}+PF6–.

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Metallorganische Lewissäuren

Cited by 18 publications

References 60 publications

Cyclopentadienone Iron Alcohol Complexes: Synthesis, Reactivity, and Implications for the Mechanism of Iron-Catalyzed Hydrogenation of Aldehydes

Cyclopentadienone Iron Alcohol Complexes: Synthesis, Reactivity, and Implications for the Mechanism of Iron-Catalyzed Hydrogenation of Aldehydes

Organometallic Lewis Acids, Part LXII. Chiral Carbonyl‐Cyclopentadienyl‐Triphenylphosphine‐Iron and ‐Ruthenium Complexes with Tertiary Nitriles [CpM(CO)(PPh₃)(N≡C–CR¹R²R³)]⁺ BF₄^– (M = Fe, Ru)

Coordination of the Ester Group – Hydrido‐Rhodium(III) and Iridium(III) Complexes of Orthometallated Diphenylmethylene Glycine Esters [1]

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Metallorganische Lewissäuren

Cited by 18 publications

References 60 publications

Cyclopentadienone Iron Alcohol Complexes: Synthesis, Reactivity, and Implications for the Mechanism of Iron-Catalyzed Hydrogenation of Aldehydes

Cyclopentadienone Iron Alcohol Complexes: Synthesis, Reactivity, and Implications for the Mechanism of Iron-Catalyzed Hydrogenation of Aldehydes

Organometallic Lewis Acids, Part LXII. Chiral Carbonyl‐Cyclopentadienyl‐Triphenylphosphine‐Iron and ‐Ruthenium Complexes with Tertiary Nitriles [CpM(CO)(PPh3)(N≡C–CR1R2R3)]+ BF4– (M = Fe, Ru)

Coordination of the Ester Group – Hydrido‐Rhodium(III) and Iridium(III) Complexes of Orthometallated Diphenylmethylene Glycine Esters [1]

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Organometallic Lewis Acids, Part LXII. Chiral Carbonyl‐Cyclopentadienyl‐Triphenylphosphine‐Iron and ‐Ruthenium Complexes with Tertiary Nitriles [CpM(CO)(PPh₃)(N≡C–CR¹R²R³)]⁺ BF₄^– (M = Fe, Ru)