Untersuchungen zur reaktivität organometallischer komplexe V. Zum sterischen verlauf der pseudocarboniumumlagerung der cyclopentadienyl[5-exo-(α-halogenalkyl)cyclopentadien]kobalt-komplexe

Herberich, Gerhard E.; Greiss, G.; Heil, Horst F.

doi:10.1016/s0022-328x(00)87731-1

Cited by 20 publications

(4 citation statements)

References 11 publications

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“…Additionally, execution of this experiment with CD 2 Cl 2 revealed m / z peaks for A that were unchanged from those measured in CH 2 Cl 2 , but peaks for C that were shifted by two m / z units to higher mass values, corresponding to incorporation of 1 equiv of (CD 2 ) into product C (see Figures S59–S62). This isotope incorporation is consistent with the established mechanism of the ring-expansion that forms C from B . ,, …”

supporting

confidence: 87%

“…Notably, Kölle and co-workers also reported that B undergoes a ring-expanding rearrangement in methanol (MeOH) at room temperature to yield Cp*Co(η 5 -C 6 Me 5 CH 2 ) ( C ), a species which features the monoanionic η 5 -C 6 Me 5 CH 2 ligand (see Scheme ) and supports a cobalt metal center in the +III oxidation state. , This ring-expanding reaction is conceptually related to the prior work on Cp 2 Co reactivity carried out by Herberich . Exposure of our synthesized B to MeOH resulted in a rapid color change and generation of the chloride salt of C .…”

supporting

confidence: 87%

“…This isotope incorporation is consistent with the established mechanism of the ring-expansion that forms C from B. 3,8,9 The mass spectra also revealed another species with m/z (M + ) = 608.1689. This signal corresponds to [Cp*Co] 3 (μ 3 -CH) 2 (D), a species first reported by Smith and Andersen in 1996 as a control compound in studies of the related [Cp*Co] 3 (μ 3 -CH)(μ 3 −H).…”

supporting

confidence: 81%

“…In particular, Herberich and co-workers led the field, finding that although Cp 2 Co does not react with CH 2 Cl 2 at room temperature, it does react with halomethanes (CH 3 X) with rates that (i) strongly depend on the identity of X and (ii) increase in the order Cl < Br < I. 2 Evidence was gathered for follow-up reactivity leading to a distinctive ring expansion of cyclopentadienyl, 3 as well as for the reactions with Cp 2 Co being radical in nature. 4 Building on this prior work, we describe in this paper the reactivity of Cp* 2 Co with CH 2 Cl 2 and identify four products arising from this reactivity.…”

mentioning

confidence: 99%

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Evidence for Reactivity of Decamethylcobaltocene with Dichloromethane

Mikeska

Blakemore

2023

Organometallics

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Decamethylcobaltocene (Cp*2Co) is commonly encountered in organometallic chemistry, where it is often used as a one-electron reductant under inert atmosphere and considered to be a stable metallocene in both its reduced [CoII] and oxidized [CoIII] forms. Here, we report that Cp*2Co is not stable in dichloromethane (CH2Cl2), a finding that contrasts markedly with the robustness of this compound in other solvents used for redox chemistry, such as neat acetonitrile (CH3CN). Parallel chemical and electrochemical studies show that when Cp*2Co comes into contact with CH2Cl2, both [Cp*2Co]+ (A) and Cp*Co(η4-C5Me5CH2Cl) (B), a species in which a chloromethyl group has been added to one Cp* ring, are generated. B subsequently undergoes a ring-expanding rearrangement if exposed to MeOH, yielding Cp*Co(η5-C6Me5CH2) (C) that is detectable by mass spectrometry (MS). [Cp*Co]3(μ3-CH)2 (D) could also be detected by MS, adding to the array of products arising from Cp*2Co that do not maintain the expected metallocene motif. Taken together, these findings suggest that Cp*2Co should be used with caution in CH2Cl2, particularly in cases in which one-electron transfer and/or clean reactivity are desired.

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supporting

confidence: 87%

supporting

confidence: 87%

supporting

confidence: 81%

mentioning

confidence: 99%

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Evidence for Reactivity of Decamethylcobaltocene with Dichloromethane

Mikeska

Blakemore

2023

Organometallics

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Bis(cyclopentadienyl)cobalt

Pauson

2001

Encyclopedia of Reagents for Organic Synthesis

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Ein neuartiger aromatischer Bor‐Heterocyclus als Ligand in einem Übergangsmetall‐π‐Komplex

1970

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7.43 (1, M) JBC = 2.5 Hz JBD= 8.0 Hz 2.44 (1, M) JBC = JB'c, = 7.5 Hz 8.00 (1, M) JBD = JB'D, = 5.5 Hz --9.33 (1, M) 6.77 (1, M) 7.10 (1, M) I [bl JAX = 3.6 Hz JAB = 4.1 Hz I -J y t -3 7Hz 8.30 (1, M) JBD = 5.7 Hz JBC = 9.3 Hz 6.77 (2. M) [bl 6.60 (2, M) [a? 7.0 (2, M) 6.9 (2, M) ca. 6.3 JAA' = 3.6 Hz 6.53 (1, M) JAK = 6.5 Hz 6.88 H B + H C Me (1,D) 8.0-8.2 (2, M) 7.77 (3, S) [cl 6.98 H B + H C Me (1, D) [cl 7.9-8.3 (2, M) 8.02 (3. S) 6.57 (2, M) [c] JAM = 4.1 Hz JAB = JA.B, = 4.9 HZ 6.65 (2, M) [a] JAM = 7.6 Hz JAB = J A B , = 6.4 Hz 8.30 (2, M) 8.80 (2, M) JBC = J B ,~ = 9.8 Hz 8.75 (2, M) JBC = JBJc' = 9.8 Hz JBB, < 0.1 Hz JAB, = JA'B = -0.2 Hz JCD = JC'D 8.2s (2, M) JBB, < 0.1 Hz JCD = JC'D JAB* = JKB = -0.2 Hz 9.20 (1,M) JCD = 3.7 Hz JBD = 5.7 HZ 8.90 (1, M) J C D , = 3.8 I J g . D = 6.4H NMR (7) UV Id1 Amax (nm; d 322 ( 180) 232 (5900) 321 ( 360) 322( 400) 272( 510) 262( 740) 254( 680) 1 Hc' I HD' I HD H c 4.85 (1, M) JCD = 17.5 Hz 5.31 (1. M) (5al 112-114 (Zers.) (6a) 135-136 (Zers.) 6.49 (2, M) [a] JAB ca. 3 Hz 6.63 (2, M) [a] JAN = 3.8 Hz JAB = J A * B~ = 4.6 Hz 6.65 (2, M) [a] JAA' = 6.7 Hz JAB = JA'B' = 6.3 HZ 7.30 (2, M) JBB, < 0.1 Hz JAB, = JA'B = -0.3 Hz 3.03 (1, D) I / JCD = 3.2 Hz 8.2 (2, M) 9.1 (2, M) 239 (4900) 273 ( 950) 267 (1220) 261 (1610) ~2 4 5 = 3800 --9.33 (1, M) 9.25 (1, M) 9.65 (2, M) = 5.2 Hz JBD = JB'D, = 5.9 Hz ~ e22g = 200 9.63 (2, M) = 5.6 Hz JBD = JB,D* = 6.3 Hz 273 (1000) 267 (1000) 9230 = 250 ~ 6.6-7.0 (2, M) [Cl JAX = 4.1 Hz 8.0-8.6 (4,M) JAB, = 0.8 Hz J A B < 0.1 Hz JAB = 4.9 Hz J M J~ = 1.4 Hz JBB' < 0.1 Hz JBC = 9.6 Hz J w c = 9.1 Hr [a] In CDCl,.[b] In CeH6.[c] In CCb.[dl In CH3OH.[el Molektlion bei rn/e = 238.[€I Molekiilion bei m/e = 391. Eingegangen am 6. August 1970 [Z 2561 fur die Reaktion von (4) rnit Borhalogeniden und Organoborhalogeniden ein Reaktionsschema erwarten, wie es hier fur das Beispiel des Phenylbordibromids (mit X = Br) angegeben wird: Das rnit dem Pyridinium-Ion (1) und dem Benzol (2) isoelektronische Hydridoborinat-Ion (3) ist nicht bekannt. O S Q ?+ Tatsachlich reagiert (4) bei -50 "C in Toluol mit Phenylbordibromid [51 zu Bis(cyclopentadieny1)kobalt-bromid und einer roten, zersetzlichen Losung 161, aus der durch Halogenid-Acceptoren bei Raumtemperatur Salze (6) abgeschieden werden. Mit SnBr4 erhalt man so das Hexabromostannat ( 6~1 , das sich durch Hydrolyse und Fallung rnit NH4PF6-LoSUng in das Hexafluorophosphat (6b) (luftbestandige, orangerote Nadeln, Fp = 139 "C) iiberfiihren IBRt. Das IH-NMR-Spektrum (Abb.) von (6b) (in CD3COCD3, gemessen gegen internes TMS bei 60 MHz und 30 "C) besteht aus dem Singulett des Cyclopentadienyl-Rings bei T = 4.16, zwei Multipletts der Phenylgruppe bei T = 2.0 und 2.6 sowie zwei Multipletts der iibrigen fiinf Protonen Wir haben nun, ausgehend von Bis(cyclopentadieny1)kobalt (4) und Borhalogeniden oder Organoborhalogeniden, erstmals obergangsmetall-x-Komplexe rnit Liganden des Typs (3) synthetisiert. In Analogie zu vorangegangenen Arbeiten iiber die Reaktion von (4) rnit organischen Halogeniden [I, 21 und iiber die ...

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Untersuchungen zur reaktivität organometallischer komplexe V. Zum sterischen verlauf der pseudocarboniumumlagerung der cyclopentadienyl[5-exo-(α-halogenalkyl)cyclopentadien]kobalt-komplexe

Cited by 20 publications

References 11 publications

Evidence for Reactivity of Decamethylcobaltocene with Dichloromethane

Evidence for Reactivity of Decamethylcobaltocene with Dichloromethane

Bis(cyclopentadienyl)cobalt

Ein neuartiger aromatischer Bor‐Heterocyclus als Ligand in einem Übergangsmetall‐π‐Komplex

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