Preparation, properties and structures of the clusters hexakis(.mu.3-oxo)pentakis(.eta.5-cyclopentadienylvanadium), [(.eta.5-C5H5)5V5O6], and tetrakis(.mu.3-oxo)tetrakis(.eta.5-cyclopentadienylchromium), [(.eta.5-C5H5)4Cr4O4]

Bottomley, Frank; Páez, Daniel E.; White, Peter S.

doi:10.1021/ja00385a016

Cited by 87 publications

(38 citation statements)

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“…= 4; the Cr–N distance average is 188.1 pm for 8a and 188.2 pm for 9b ). This interpretation explains also the larger Cr ··· Cr distances in the tetraphosphorus derivative [(Cp*Cr) 4 (µ 3 ‐P) 4 ] as a consequence of the longer Cr–P bonds (226.2 pm average) …”

Section: Resultsmentioning

confidence: 85%

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Paramagnetic Chromium(II) Complexes and Chromium(IV) Nitrides with Bulky Alkylcyclopentadienyl Ligands

et al. 2018

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Easily available chromium(II) acetate was used for an entry into chromium chemistry: sodium tetraisopropylcyclopentadienide (Na4Cp), sodium 1,2,4‐tri(tert‐butyl)cyclopentadienide (NaCp′′′), or lithium pentaisopropylcyclopentadienide (Li5Cp) convert the acetate to the acetate‐bridged dimers [4CpCr(µ‐OOCCH3)]2 (1a), [Cp′′′Cr(µ‐OOCCH3)]2 (1b), or [5CpCr(µ‐OOCCH3)]2 (1c) in yields well above 70 %. These acetates could be converted into the halide‐bridged dimers [4CpCr(µ‐Cl)]2 (2a), [4CpCr(µ‐Br)]2 (3a), [Cp′′′Cr(µ‐Br)]2 (3b), or [5CpCr(µ‐Br)]2 (3c), [4CpCr(µ‐I)]2 (4a), or [Cp′′′Cr(µ‐I)]2 (4b) with the corresponding trimethylsilyl halides in nearly quantitative yield. With bis(trimethylsilyl)sulfate the acetate 1a gave crude bis(tetraisopropylcyclopentadienylchromium)sulfate (5a). From the bromide 3b and sodium bis(trimethylsilyl)amide the mononuclear chromium(II) silylamide [Cp′′′CrN(SiMe3)2(THF)] (7b) was obtained as a tetrahydrofuran adduct. Upon reaction with sodium azide, the iodide 4a afforded the tetranuclear chromium(IV) nitride cubane [(4CpCr)3(µ3‐N)4CrOH] (8a) after extraction with heptane containing traces of water. The analogous chromium nitride derivative [(Cp′′′Cr)3(µ3‐N)4CrBr] (9b) was obtained from the bromide 3b and sodium azide.

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Section: Resultsmentioning

confidence: 85%

“…8a forms a slightly distorted cubane with edges between 184 and 189 pm, N–Cr–N angles from 90.7 to 93.8°, and Cr–N–Cr angles from 87.6 to 89.4°. The [CpCr(µ 3 ‐O)] 4 cubane has longer edges (193–195 pm) and longer Cr ··· Cr distances between 270 and 290 pm . The Cr III ··· Cp cent.…”

Section: Resultsmentioning

confidence: 99%

Paramagnetic Chromium(II) Complexes and Chromium(IV) Nitrides with Bulky Alkylcyclopentadienyl Ligands

et al. 2018

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“…Hence, the Union Carbide ethylene polymerization catalyst is generated from the reaction chromocene with silanol on partially dehydrated silica [43]. Cyclopentadienyl ring loss from Cp 2 Cr also occurs when it is reacted with the Arduengo carbene tetramethylimidazol-2-ylidene [44], the diazene Me 3 SiN=NSiMe 3 [45], and when it is oxidized with O 2 [46], Me 3 NO [47] and N 2 O [48].…”

Section: Reactivitymentioning

confidence: 99%

The Elusive Chemistry of Bent-Sandwich Chromocene

Shapiro¹

2007

COC

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Until recently the chemistry of bent-sandwich chromocene eluded examination due to the propensity of dicyclopentadienylchromium toward cyclopentadienyl ring loss and thermodynamic barriers to coordinating two electron donating ligands such as CO. The use of modified cyclopentadienyl ligands such as acyclic pentadienyl ligands and linked dicyclopentadienyl ligands, by changing the electronic demands of the metal, have allowed access to neutral and cationic bent-sandwich chromocene derivatives with interesting structures, redox properties, and ligand coordination/substitution behavior. This review article provides an overview of the synthesis, magnetic properties, and reactivity of Cp 2 Cr (Cp = C 5 H 5 ) and related compounds, the chemistry of open chromocene compounds containing acyclic pentadienyl ligands, and a more detailed discussion of the chemistry of ansa-chromocene complexes, which has been the research focus of the author. INTRODUCTIONThe chemistry of dicyclopentadienylchromium (chromocene) [1,2] has been less illustrious than that of metallocenes of other early transition metals from groups 3-6, some of which are recognized for their catalytic activity toward alkene and alkyne polymerization and other synthetically useful reactions while others have served as model systems for fundamentally interesting transition metal mediated reactions [3]. This situation is due to chromocene's preference for a parallel-ring geometry, which allows it to maintain a high spin electronic configuration with a 3 E 2g (e 2g 3 a 1g

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“…Oxotransfer from N 2 O can lead to formation of metal-oxo complexes or oxidation of ligands contained in the metal complex. In pioneering research of N 2 O reactivity, Bottomley and coworkers [188][189][190][191][192] N 2 O insertion into a metal-ligand bond has been observed with Group IV metallocene complexes (Scheme 2.9) [194]. When reported, these transformations were unprecedented since reactions between N 2 O and metal complexes usually lead to extrusion of N 2 .…”

Section: Oxo Transfer Reactionsmentioning

confidence: 99%