Preparation and Structure of [AsPh4]2[HFe7(CO)20B]. Evidence for the Sequential Encapsulation of a Boron Atom into an Iron Cage by a Radical-Driven Cluster-Building Process

Bandyopadhyay, Ananda K.; Shang, Maoyu; Jun, Chang Soo; Fehlner, Thomas P.

doi:10.1021/ic00095a010

Cited by 26 publications

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“…Further, the facile formation of radical species in metal carbonyl systems − and evidence for radical participation in cluster fragment addition and exchange reactions in metal carbonyl systems have been reported . We have suggested that ferraborane cluster-building reactions with Fe 2 (CO) 9 proceed via a radical mechanism . Consistent with “the apparent necessity of employing dianion clusters...”, we found a dependence of reactivity on the charge of the anionic ferraborane precursor in this system.…”

Section: Discussionsupporting

confidence: 86%

“…Competition between deactivation of the adduct and base-facilitated loss of Fe(CO) 5 determines whether net addition or substitution is observed. This mechanism is very similar to those proposed earlier for related systems except that H atom transfer rather than electron transfer plays the prominent role although Co(CO) 4 • is the radical carrier in both cases. ,, …”

Section: Discussionsupporting

confidence: 86%

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Synthesis of B₂H₅FeCo(CO)₆, Fe₂Co(CO)₉(μ-CO)BH₂, FeCo₂(CO)₉(μ-CO)BH, FeCo₂(CO)₉(BH)₂, and HFe₃Co(CO)₁₂BH. Co(CO)₃Fragment Addition and Fragment Exchange in Ferraborane Clusters

1996

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The reactions of Co2(CO)8 with the ferraboranes B2H6Fe2(CO)6, HFe3(CO)9BH4, HFe3(CO)10BH2, and HFe4(CO)12BH2 lead to fragment addition and/or fragment exchange. Thus, the new mixed-metal metallaboranes B2H5FeCo(CO)6 (1), Fe2Co(CO)9(μ-CO)BH2 (2), FeCo2(CO)9(μ-CO)BH (3), FeCo2(CO)9(BH)2 (4), and HFe3Co(CO)12BH (5) have been isolated in modest yields and characterized spectroscopically. Comparison of selected spectroscopic and chemical properties of isoelectronic pairs of hetero- and homometallaboranes defines the perturbation of the cluster network by the replacement of HFe by Co. Both direct effects due to the different metal atoms and indirect effects resulting from the differing number of skeletal hydrogen atoms are observed. Consistent with the radical mechanism suggested for Co(CO) x fragment addition to and exchange with organometallic clusters, a radical mechanism is proposed. However, the metallaborane reactions require neutral molecules and appear to be initiated by H atom transfer whereas the analogous anionic organometallic reactions proceed via electron transfer.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionsupporting

confidence: 86%

Synthesis of B₂H₅FeCo(CO)₆, Fe₂Co(CO)₉(μ-CO)BH₂, FeCo₂(CO)₉(μ-CO)BH, FeCo₂(CO)₉(BH)₂, and HFe₃Co(CO)₁₂BH. Co(CO)₃Fragment Addition and Fragment Exchange in Ferraborane Clusters

1996

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“…Many of the observations concern tetrahedral M 3 E clusters, , and in at least one instance involving Co 2 (CO) 8 , the presence of a radical pathway is strongly implicated , On the other hand, although cluster degradation by Lewis bases is well-established, the effective degradation by a metal fragment, as seen in the formation of 3 , is not. Undoubtedly it takes place but may be hidden in many cases by the complexity of the systems.…”

Section: Resultsmentioning

confidence: 99%

Reactions of the Cobaltaborane 2,4-{(η⁵-C₅Me₅)Co}₂B₃H₇with Metal Fragments. Synthesis and Characterization ofnido-1-{(η⁵-C₅Me₅)Co}-2-{(CO)₃Fe}B₃H₇andarachno-(η⁵-C₅Me₅)(CO)CoB₃H₇

1998

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The reactions of nido-2,4-(Cp*Co) 2 B 3 H 7 , 1, Cp* ) (η 5 -C 5 Me 5 ), with Fe 2 (CO) 9 and Co 2 (CO) 8 generate seven skeletal electron pair (sep) nido-1-{Cp*Co}-2-((CO) 3 Fe)B 3 H 7 , 2, by metal fragment substitution and seven sep arachno-Cp*(CO)CoB 3 H 7 , 3, by metal fragment degradation. Both compounds are characterized spectroscopically in solution and with singlecrystal X-ray diffraction in the solid state. On the basis of the results and related chemistry, the suggested reaction pathway involves M(CO) 4 , M ) Fe and Co, coordination to a Co-H-B edge of 1 followed by loss of Cp*Co(CO) which leads to 2. We postulate that the cobalt analogue of 2, which would be an odd-electron species, readily loses a cobalt carbonyl fragment to form 3. metal fragment substitution in one case and metal fragment loss in the other. The former has been observed in related organometallic clusters 23 as well as metallaborane chemistry. 24 The latter constitutes a new route to so-called "borallyl" complexes previously prepared from [B 3 H 8 ]and mononuclear metal complexes of Ir, 25,26 Pd,27,28 and Pt 29-31 with phosphine ancillary ligands. Here a first-row transition-metal analogue is synthesized by building up a B 3 H 7 fragment on a dicobalt framework followed by removal of one metal fragment. A previous attempt to make a cobalt borallyl complex by reacting (PPh 3 ) 2 CoCl 2 with [B 3 H 8 ]led only to the phosphine adduct B 3 H 7 PPh 3 . 25 Experimental SectionGeneral. All operations were conducted under a dinitrogen atmosphere using standard Schlenk techniques. 32 Solvents were distilled before use under N2 as follows: sodium benzophenone ketyl for hexane, diethyl ether, and tetrahydrofuran. The starting material nido-2,4-(Cp*Co)2B3H7, 1, was prepared according to published procedures. 16 Fe2(CO)9 (Aldrich) and Co2(CO)8 (Strem) were used as received. NMR spectra were recorded on a 300 or 500 MHz Varian FT-NMR spectrometer. The solvent proton signal was used as a reference for 1 H NMR (δ, ppm, benzene, 7.15), while a sealed tube containing [Et4N][B3H8] in acetone-d6 (-29.7 ppm) was used as the external reference for 11 B NMR. Infrared spectra were obtained on a Nicolet 205 FT-IR spectrometer. Mass spectra were obtained on a Finnigan MAT model 8400 mass spectrometer with EI mode. Perfluorokersene was used as the standard for the high-resolution EI mass spectra. Elemental analysis was performed by M-H-W Laboratories, Phoenix, AZ. nido-1-(Cp*Co)-2-{(CO)3Fe}B3H7, 2.In a 200 mL Schlenk tube, nido-2,4-(Cp*Co)2B3H7, 1 (0.40 g, 0.94 m.mol), and Fe2-(CO)9 (0.43 g, 1.18 mmol) were loaded. A 15 mL amount of freshly distilled toluene was slowly added to the mixture by syringe. The reaction mixture was stirred at ca. 50°C for 6 h. During this period, a black solid and a dark brown solution were observed to form. The toluene was then removed under vacuum, and the resulting residue was extracted with hexane and filtered through Celite. Low-temperature column chromatography (-40°C) was performed. Elution with hexane gave a brown solution o...

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“…[HFe 7 (CO) 20 B] 22 . 9 Just as with 1, conversion of two M vertices to BH and BCl followed by rearrangement leads to the observed geometry. The predicted cve count is 82 as observed.…”

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confidence: 86%

Designer clusters: synthesis and characterization of Cp2Rh2Co3(CO)8B3HCl (Cp =η5-C5Me5)

Lei¹,

Shang²,

Fehlner³

1999

Chem. Commun.

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Preparation and Structure of [AsPh4]2[HFe7(CO)20B]. Evidence for the Sequential Encapsulation of a Boron Atom into an Iron Cage by a Radical-Driven Cluster-Building Process

Cited by 26 publications

References 0 publications

Synthesis of B₂H₅FeCo(CO)₆, Fe₂Co(CO)₉(μ-CO)BH₂, FeCo₂(CO)₉(μ-CO)BH, FeCo₂(CO)₉(BH)₂, and HFe₃Co(CO)₁₂BH. Co(CO)₃Fragment Addition and Fragment Exchange in Ferraborane Clusters

Synthesis of B₂H₅FeCo(CO)₆, Fe₂Co(CO)₉(μ-CO)BH₂, FeCo₂(CO)₉(μ-CO)BH, FeCo₂(CO)₉(BH)₂, and HFe₃Co(CO)₁₂BH. Co(CO)₃Fragment Addition and Fragment Exchange in Ferraborane Clusters

Reactions of the Cobaltaborane 2,4-{(η⁵-C₅Me₅)Co}₂B₃H₇with Metal Fragments. Synthesis and Characterization ofnido-1-{(η⁵-C₅Me₅)Co}-2-{(CO)₃Fe}B₃H₇andarachno-(η⁵-C₅Me₅)(CO)CoB₃H₇

Designer clusters: synthesis and characterization of Cp2Rh2Co3(CO)8B3HCl (Cp =η5-C5Me5)

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Preparation and Structure of [AsPh4]2[HFe7(CO)20B]. Evidence for the Sequential Encapsulation of a Boron Atom into an Iron Cage by a Radical-Driven Cluster-Building Process

Cited by 26 publications

References 0 publications

Synthesis of B2H5FeCo(CO)6, Fe2Co(CO)9(μ-CO)BH2, FeCo2(CO)9(μ-CO)BH, FeCo2(CO)9(BH)2, and HFe3Co(CO)12BH. Co(CO)3Fragment Addition and Fragment Exchange in Ferraborane Clusters

Synthesis of B2H5FeCo(CO)6, Fe2Co(CO)9(μ-CO)BH2, FeCo2(CO)9(μ-CO)BH, FeCo2(CO)9(BH)2, and HFe3Co(CO)12BH. Co(CO)3Fragment Addition and Fragment Exchange in Ferraborane Clusters

Reactions of the Cobaltaborane 2,4-{(η5-C5Me5)Co}2B3H7with Metal Fragments. Synthesis and Characterization ofnido-1-{(η5-C5Me5)Co}-2-{(CO)3Fe}B3H7andarachno-(η5-C5Me5)(CO)CoB3H7

Designer clusters: synthesis and characterization of Cp*2Rh2Co3(CO)8B3HCl (Cp* =η5-C5Me5)

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Synthesis of B₂H₅FeCo(CO)₆, Fe₂Co(CO)₉(μ-CO)BH₂, FeCo₂(CO)₉(μ-CO)BH, FeCo₂(CO)₉(BH)₂, and HFe₃Co(CO)₁₂BH. Co(CO)₃Fragment Addition and Fragment Exchange in Ferraborane Clusters

Synthesis of B₂H₅FeCo(CO)₆, Fe₂Co(CO)₉(μ-CO)BH₂, FeCo₂(CO)₉(μ-CO)BH, FeCo₂(CO)₉(BH)₂, and HFe₃Co(CO)₁₂BH. Co(CO)₃Fragment Addition and Fragment Exchange in Ferraborane Clusters

Reactions of the Cobaltaborane 2,4-{(η⁵-C₅Me₅)Co}₂B₃H₇with Metal Fragments. Synthesis and Characterization ofnido-1-{(η⁵-C₅Me₅)Co}-2-{(CO)₃Fe}B₃H₇andarachno-(η⁵-C₅Me₅)(CO)CoB₃H₇

Designer clusters: synthesis and characterization of Cp2Rh2Co3(CO)8B3HCl (Cp =η5-C5Me5)