Mixed cobalt/gold clusters based on octahedral or prismatic Co6C skeletons

Reina, Roser; Riba, Olga; Rossell, Oriol; Seco, Miquel; Montauzon, Dominique de; Pellinghelli, Maria Angela; Tiripicchio, António; Font-Bardı́a, Mercè; Soláns, Xavier

doi:10.1039/b005651k

Cited by 11 publications

(18 citation statements)

References 25 publications

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“…Most notably, a resonance appears at 463.0 ppm. This compares with resonances observed for [Co 6 C(CO) 13 {AuPPh 3 }] - , [Fe 5 MoAuC(CO) 17 (L)] - , and [Fe 5 C(CO) 14 {HgM}] -57 suggesting the presence of a carbide carbon.…”

Section: Resultssupporting

confidence: 54%

Divergent Pathways of C−H Bond Activation: Reactions of (t-Bu₃PN)₂TiMe₂ with Trimethylaluminum

2002

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The reaction of AlMe(3) with (t-Bu(3)PN)(2)TiMe(2) 1 proceeds via competitive reactions of metathesis and C-H activation leading ultimately to two Ti complexes: [(mu(2)-t-Bu(3)PN)Ti(mu-Me)(mu(4)-C)(AlMe(2))(2)](2) 2, [(t-Bu(3)PN)Ti(mu(2)-t-Bu(3)PN)(mu(3)-CH(2))(2)(AlMe(2))(2)(AlMe(3))] 3, and the byproduct (Me(2)Al)(2)(mu-CH(3))(mu-NP(t-Bu(3))) 4. X-ray structural data for 2 and 3 are reported. Compound 3 undergoes thermolysis to generate a new species [Ti(mu(2)-t-Bu(3)PN)(2)(mu(3)-CH(2))(mu(3)-CH)(AlMe(2))(3)] 5. Monitoring of the reaction of 1 with AlMe(3) by (31)P[(1)H] NMR spectroscopy revealed intermediates including (t-Bu(3)PN)TiMe(3) 6. Compound 6 was shown to react with AlMe(3) to give 2 exclusively. Kinetic studies revealed that the sequence of reactions from 6 to 2 involves an initial C-H activation that is a second-order reaction, dependent on the concentration of Ti and Al. The second-order rate constant k(1) was 3.9(5) x 10(-4) M(-1) s(-1) (DeltaH(#) = 63(2) kJ/mol, DeltaS(#) = -80(6) J/mol x K). The rate constants for the subsequent C-H activations leading to 2 were determined to be k(2) = 1.4(2) x 10(-3) s(-1) and k(3) = 7(1) x 10(-3) s(-1). Returning to the more complex reaction of 1, the rate constant for the ligand metathesis affording 4 and 6 was k(met) = 6.1(5) x 10(-5) s(-1) (DeltaH(#) = 37(3) kJ/mol, DeltaS(#) = -203(9) J/mol x K). The concurrent reaction of 1 leading to 3 was found to proceed with a rate constant of k(obs) of 6(1) x 10(-5) s(-1) (DeltaH(#) = 62(5) kJ/mol, DeltaS(#)= -118(17) J/mol x K). Using these kinetic data for these reactions, a stochastic kinetic model was used to compute the concentration profiles of the products and several intermediates with time for reactions using between 10 and 27 equivalents of AlMe(3). These models support the view that equilibrium between 1 x AlMe(3) and 1 x (AlMe(3))(2) accounts for varying product ratios with the concentration of AlMe(3). In a similar vein, similar equilibria account for the transient concentrations of 6 and an intermediate en route to 3. The implications of these reactions and kinetic and thermodynamic data for both C-H bond activation and deactivation pathways for Ti-phosphinimide olefin polymerization catalysts are considered and discussed.

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Section: Resultssupporting

confidence: 54%

Divergent Pathways of C−H Bond Activation: Reactions of (t-Bu₃PN)₂TiMe₂ with Trimethylaluminum

2002

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“…(c) µ 3 –µ, Au–Au: The cluster contains one µ 3 (face‐bridging) and one µ (edge‐bridging) AuPR 3 fragment at a bonding distance as found in Ru 5 WC(CO) 17 (AuPEt 3 ) 2 , Rh 6 C(CO) 13 (AuPPh 3 ) 2 , and Co 6 C(CO) 13 (AuPPh 3 ) 2 ;…”

Section: Resultsmentioning

confidence: 98%

Synthesis of the Highly Reduced [Fe₆C(CO)₁₅]^4– Carbonyl Carbide Cluster and Its Reactions with H⁺ and [Au(PPh₃)]⁺

et al. 2017

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The reduction of [Fe6C(CO)16]2– (1) with NaOH in DMSO or with Na/naphthalene in THF affords the highly reduced [Fe6C(CO)15]4– (2) monocarbide tetraanion. The molecular structure of 2 has been crystallographically determined as its [Et4N]4[Fe6C(CO)15]·CH3CN salt, revealing an octahedral structure as expected for a hexanuclear cluster possessing 86 valence electrons. The stepwise protonation of 2 with strong acids such as HBF4·Et2O results first in the monohydride trianion [HFe6C(CO)15]3– (3) and then the purported dihydride dianion [H2Fe6C(CO)15]2– (4), as indicated by 1H NMR spectroscopy. Both 3 and 4 are not stable enough to be isolated and rapidly decompose, yielding the parent dianion 1. The reaction of 2 with a slight excess of Au(PPh3)Cl affords the aurated dianion [Fe6C(CO)15(AuPPh3)2]2– (5), which has been isolated and structurally characterized as its [Et4N]2[Fe6C(CO)15(AuPPh3)2]·2CH3CN salt. DFT calculations allowed us to study, from a computational point of view, the electronic features of the new compounds and possible reaction intermediates.

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“…The resonance at 51.9 ppm may be assigned to [Co 6 C(CO) 12 (AuPPh 3 ) 2 ] 2− by comparison to literature data. 26 The resonance at 58.0 ppm may be tentatively assigned to a more dissociated [Co 6 C(CO) 12 (AuPPh 3 )] 3− species (eq 4):…”

Section: Resultsmentioning

confidence: 99%

Octahedral Co-Carbide Carbonyl Clusters Decorated by [AuPPh₃]⁺Fragments: Synthesis, Structural Isomerism, and Aurophilic Interactions of Co₆C(CO)₁₂(AuPPh₃)₄

et al. 2014

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The Co6C(CO)12(AuPPh3)4 carbide carbonyl cluster was obtained from the reaction of [Co6C(CO)15](2-) with Au(PPh3)Cl. This new species was investigated by variable-temperature (31)P NMR spectroscopy, X-ray crystallography, and density functional theory methods. Three different solvates were characterized in the solid state, namely, Co6C(CO)12(AuPPh3)4 (I), Co6C(CO)12(AuPPh3)4·THF (II), and Co6C(CO)12(AuPPh3)4·4THF (III), where THF = tetrahydrofuran. These are not merely different solvates of the same neutral cluster, but they contain three different isomers of Co6C(CO)12(AuPPh3)4. The three isomers I-III possess the same octahedral [Co6C(CO)12](4-) carbido-carbonyl core differently decorated by four [AuPPh3](+) fragments and showing a different Au(I)···Au(I) connectivity. Theoretical investigations suggest that the formation in the solid state of the three isomers during crystallization is governed by packing and van der Waals forces, as well as aurophilic and weak π-π and π-H interactions. In addition, the closely related cluster Co6C(CO)12(PPh3)(AuPPh3)2 was obtained from the reaction of [Co8C(CO)18](2-) with Au(PPh3)Cl, and two of its solvates were crystallographically characterized, namely, Co6C(CO)12(PPh3)(AuPPh3)2·toluene (IV) and Co6C(CO)12(PPh3)(AuPPh3)2·0.5toluene (V). A significant, even if minor, effect of the cocrystallized solvent molecules on the structure of the cluster was observed also in this case.

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Mixed cobalt/gold clusters based on octahedral or prismatic Co6C skeletons

Cited by 11 publications

References 25 publications

Divergent Pathways of C−H Bond Activation: Reactions of (t-Bu₃PN)₂TiMe₂ with Trimethylaluminum

Divergent Pathways of C−H Bond Activation: Reactions of (t-Bu₃PN)₂TiMe₂ with Trimethylaluminum

Synthesis of the Highly Reduced [Fe₆C(CO)₁₅]^4– Carbonyl Carbide Cluster and Its Reactions with H⁺ and [Au(PPh₃)]⁺

Octahedral Co-Carbide Carbonyl Clusters Decorated by [AuPPh₃]⁺Fragments: Synthesis, Structural Isomerism, and Aurophilic Interactions of Co₆C(CO)₁₂(AuPPh₃)₄

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Mixed cobalt/gold clusters based on octahedral or prismatic Co6C skeletons

Cited by 11 publications

References 25 publications

Divergent Pathways of C−H Bond Activation: Reactions of (t-Bu3PN)2TiMe2 with Trimethylaluminum

Divergent Pathways of C−H Bond Activation: Reactions of (t-Bu3PN)2TiMe2 with Trimethylaluminum

Synthesis of the Highly Reduced [Fe6C(CO)15]4– Carbonyl Carbide Cluster and Its Reactions with H+ and [Au(PPh3)]+

Octahedral Co-Carbide Carbonyl Clusters Decorated by [AuPPh3]+Fragments: Synthesis, Structural Isomerism, and Aurophilic Interactions of Co6C(CO)12(AuPPh3)4

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Divergent Pathways of C−H Bond Activation: Reactions of (t-Bu₃PN)₂TiMe₂ with Trimethylaluminum

Divergent Pathways of C−H Bond Activation: Reactions of (t-Bu₃PN)₂TiMe₂ with Trimethylaluminum

Synthesis of the Highly Reduced [Fe₆C(CO)₁₅]^4– Carbonyl Carbide Cluster and Its Reactions with H⁺ and [Au(PPh₃)]⁺

Octahedral Co-Carbide Carbonyl Clusters Decorated by [AuPPh₃]⁺Fragments: Synthesis, Structural Isomerism, and Aurophilic Interactions of Co₆C(CO)₁₂(AuPPh₃)₄