(Cyclopentadienyl) metal cluster complexes of the group 9 transition metals

Wadepohl, Hubert; Gebert, Stefan

doi:10.1016/0010-8545(95)01138-f

Cited by 40 publications

(18 citation statements)

References 139 publications

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“…The gross geometry of the (CpCo) 3 (μ 3 -arene) cluster unit in 3d nicely matches that of many other neutral (non-protonated) complexes of this type. ,, However, the (CpCo) 3 (μ 3 -arene) moiety is expanded compared to 1d . This affects mainly the cobalt−cobalt bonds (2.604 Å (av) in 3d vs 2.504 Å (av) in 1d ), but the distances from the cobalt atoms to the μ 3 -arene are also somewhat longer in 3d ( d [Co−C(μ-arene)] av = 2.068 Å ( 3d ) vs 2.034 Å ( 1d )).…”

Section: Discussionsupporting

confidence: 62%

Organometallic Cluster Complexes with Face-Capping Arene Ligands. 8. Nucleophilic Reactivity of Cluster Complexes with Face-Capping Arene Ligands: Metal vs Ligand Protonation

et al. 1996

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Protonation of some cluster complexes with face-capping arene ligands has been studied. The complexes [(CpCo) 3 (µ 3 -η 2 :η 2 :η 2 -arene)] [arene ) isopropylbenzene (1a), 1,4-diethylbenzene (1b), 1,2-diphenylethane (1c), 1,1-diphenylethane (1d)] are protonated at the metal clusters to afford the hydrido cluster cations [(µ 3 -H)(CpCo) 3 (µ 3 -η 2 :η 2 :η 2 -arene)] + (3a-d). The crystal structure of 3d[CF 3 COO] -‚H 2 O has been determined. In marked contrast, derivatives with µ 3 -arenes bearing unsaturated substituents [arene ) R-methylstyrene (2a), β-methylstyrene (2b), p-methoxystyrene (2c)] take up a proton at the β-carbon atom of the side chain to give the novel metal cluster stabilized benzyl cations [(CpCo -c). On attempted crystallization as a tetrafluoroborate, the derivative 4a with a protonated R-methylstyrene ligand is converted to the paramagnetic [(CpCo) 3 {µ 3 -η 2 :η 2 :η 2 -(R-methylstyrene)}] + (2a + ), the crystal structure of which is reported. The different sites of protonation for 1 and 2 are explained by an extended Hu ¨ckel (EH) MO study, using both charge and overlap control arguments. The paramagnetic cation was studied, and its geometry found to agree very well with the experimentally determined structure described for 2a + , suggesting that it is indeed this the species being observed. A detailed analysis of the geometrical preferences of the protonation products 4 was carried out, using EH and density functional methods. A slipped eclipsed arrangement of a nonplanar η 7 -benzyl ligand on top of the Co 3 cluster with the side chain bent away appears to be energetically favored over a staggered substituted benzene.

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Section: Discussionsupporting

confidence: 62%

Organometallic Cluster Complexes with Face-Capping Arene Ligands. 8. Nucleophilic Reactivity of Cluster Complexes with Face-Capping Arene Ligands: Metal vs Ligand Protonation

et al. 1996

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“…This can be understood by considering the variable hapticity of the cyclopentadienyl ligand, which can take on the values g 5 , g 3 , or g variable hapticity of cyclopentadienyl, each of these clusters must have at least one 17-or 19-electron metal center, as deduced from electron counting arguments. 33 The Co 3 Cp 4 + cluster complex may be similar to those observed previously in solution [34][35][36] but lacks the requisite additional non-cyclopentadienyl ligands to form stable 18-electron structures. In the lowest mass range there resides the base peak corresponding to cobaltocenium (CoCp 2…”

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confidence: 63%

Reactive MALDI mass spectrometry: application to high mass alkanes and polyethylene

Wallace

2007

Chem. Commun.

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“…(6) The extra features correspond to “forbidden” transitions allowed by quadrupole coupling or hyperfine anisotropy. Although these phenomena may indeed allow transitions in which both the electron and nuclear spin flip, resulting in extra lines between the allowed lines, their transition probabilities are proportional to sin 2 (2θ)/ K , where θ is the angle between the field and the parallel axis and K is the angle-dependent coupling constant . For large A z , the transition probability is vanishingly small for orientations close to the parallel axis.…”

Section: Resultsmentioning

confidence: 99%

“…Easily deformed metal clusters are of interest in terms of both their fluxional and isomerization processes. , Although studies of homoleptic metal carbonyls have dominated this research area, a class of compounds in which groups of three carbonyl ligands are replaced by isolobal cyclopentadienyl anions (Cp) has also received a great deal of attention. , The latter complexes, having metal-to-CO ratios of approximately unity, may be relevant as models of small molecules such as carbon monoxide adsorbed onto metal surfaces …”

Section: Introductionmentioning

confidence: 99%

Geometric Preferences of Tricobalt Clusters Having 47−49 Valence Electron Counts: Deceptively Simple Cyclic Voltammetric Responses and EPR Evidence for Exchange-Coupled Dimers in Frozen Solutions

1998

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Oxidations and reductions of a series of 48-electron (e-) metal clusters containing a tricobalt core have been investigated by voltammetry, electrolysis, IR spectroelectrochemistry, and EPR spectroscopy. Three isomers of Cp3Co3(CO)3 have been studied. The all-CO-bridging isomer C 3 v Cp3Co3(μ-CO)3 (1B) is stable in the 48 e- and 49 e- forms, but the 47 e- cation isomerizes to a doubly-CO-bridging structure 1T +. The other two isomers, Cp3Co3(μ3-CO)(μ-CO)2 (1F) and Cp3Co3(μ-CO)2(CO) (1T), are present in about a 1:1 ratio near room temperature, but their solutions show only Nernstian 1 e- cyclic voltammetry (CV) responses. IR spectroelectrochemistry and analysis of the E 1/2 values show that the deceptively simple CV responses arise from a rapid equilibration between isomers 1F and 1T, rather than from a lack of structural change accompanying charge transfer. The cluster Cp*2Cp‘Co3(μ3-CO)(μ-CO)2 (3) (Cp* = C5Me5, Cp‘ = C5MeH4) is shown to retain its isomeric identity through three cluster oxidation states, most likely owing to a steric preference for a face-bridging carbonyl ligand in the ring-substituted complex. The 49 e- anions of the tricobalt complexes display EPR spectra consistent with a SOMO which is antibonding in the trimetallic plane. Additional regular hyperfine features in glassy matrices at 77 K are assigned to dimers consisting of a 49 e- anion magnetically coupled to either a 48 e- neutral precursor or another 49 e- anion.

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(Cyclopentadienyl) metal cluster complexes of the group 9 transition metals

Cited by 40 publications

References 139 publications

Organometallic Cluster Complexes with Face-Capping Arene Ligands. 8. Nucleophilic Reactivity of Cluster Complexes with Face-Capping Arene Ligands: Metal vs Ligand Protonation

Organometallic Cluster Complexes with Face-Capping Arene Ligands. 8. Nucleophilic Reactivity of Cluster Complexes with Face-Capping Arene Ligands: Metal vs Ligand Protonation

Reactive MALDI mass spectrometry: application to high mass alkanes and polyethylene

Geometric Preferences of Tricobalt Clusters Having 47−49 Valence Electron Counts: Deceptively Simple Cyclic Voltammetric Responses and EPR Evidence for Exchange-Coupled Dimers in Frozen Solutions

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