Metal carbide clusters synthesis systematics for heteronuclear species

Tachikawa, M.; Geerts, Rolf L.; Muetterties, E. L.

doi:10.1016/s0022-328x(00)93947-0

Cited by 89 publications

(54 citation statements)

References 2 publications

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“…Might that electron density be so attractive to various electrophiles (perhaps including N 2 ) that the cluster is inevitably isolated with a species bound there? Interstitial carbon atoms are common in high nuclearity metal cage clusters [71], perhaps for the same reason. Reductive activation of FeMoco beyond the state crystallized might cause the dissociation of that species, thereby allowing for substrate binding.…”

Section: 7 Post-script: Nitrogenasementioning

confidence: 99%

Metal–metal bonds in biology

Lindahl

2012

Journal of Inorganic Biochemistry

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Nickel-containing carbon monoxide dehydrogenases, acetyl-CoA synthases, nickel-iron hydrogenases, and diron hydrogenases are distinct metalloenzymes yet they share a number of important characteristics. All are O2-sensitive, with active-sites composed of iron and/or nickel ions coordinated primarily by sulfur ligands. In each case, two metals are juxtaposed at the “heart” of the active site, within range of forming metal-metal bonds. These active-site clusters exhibit multielectron redox abilities and must be reductively activated for catalysis. Reduction potentials are milder than expected based on formal oxidation state changes. When reductively activated, each cluster attacks an electrophilic substrate via an oxidative addition reaction. This affords a two-electron-reduced substrate bound to one or both metals of an oxidized cluster. M-M bonds have been established in hydrogenases where they serve to initiate the oxidative addition of protons and perhaps stabilize active sites in multiple redox states. The same may be true of the CODH and ACS active sites – Ni-Fe and Ni-Ni bonds in these sites may play critical roles in catalysis, stabilizing low-valence states and initiating oxidative addition of CO2 and methyl group cations, respectively. In this article, the structural and functional commonalities of these metalloenzyme active sites are described, and the case is made for the formation and use of metal-metal bonds in each enzyme mentioned. As a post-script, the importance of Fe-Fe bonds in the nitrogenase FeMoco active site is discussed.

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Section: 7 Post-script: Nitrogenasementioning

confidence: 99%

Metal–metal bonds in biology

Lindahl

2012

Journal of Inorganic Biochemistry

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“…Chemosorption of this type was demon strated by the study of the adsorption of carbonyl com plexes Cr(СО) 6 and C 5 H 5 Mn(СО) 3 on metallic sur faces 46,47 and different carbonyls, including iron carbon yls on oxide supports. 48, 49 After adsorption, a radical ion center is nucleated, which determines the radical nature of the process as a whole.…”

Section: Resultsmentioning

confidence: 99%

“…4,5 Iron carbidocarbonyl cluster Fe 5 С(СО) 15 was synthesized according to a previously described procedure. 6,7 All carbonyls used are volatile and easily decompose, which makes it possible to significantly decrease the tem perature of thermal dissociation compared to that, e.g., of oxides, to reject the use of explosive and corrosion active me dia (hydrogen, chlorine, etc. ), and to use supports of different shapes.…”

Section: Methodsmentioning

confidence: 99%

Thermal dissociation of iron carbonyls during growth of iron whiskers

et al. 2004

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Methods for the preparation of iron whiskers in chemical transport reactions of thermal dissociation of iron penta and dodecacarbonyls and carbidocarbonyl clusters Fe 5 С(СО) 15 were described. The morphology, structure, and chemical composition of the whiskers were studied. The main factors determining the growth rate and mechanical properties of the whiskers were revealed. A model for the mechanism of thermal dissociation of iron carbonyls was proposed. This process was shown to be a chain radical ion reaction initiated via the scheme of activating complex formation. Analogies between the thermal dissociation of iron carbonyls in the adsorption layer and the known radical ion processes in the liquid and gas phases were found.Metal whiskers are characterized by high ratios (20-25) of the length to apparent diameter and represent a peculiar type of inorganic material finding wide use in the recent time due to its perfect crystal structure and, as a consequence, a high mechanical strength, a considerable resistance toward oxidation, and unique electrophysical properties. In particular, they are used for the develop ment of new composite materials with metallic and poly meric matrices and for the production of magneto dielectric cores and high efficiency emitters. 1 Different methods for growing metal whiskers in the solid, liquid, and gas phases are known. Of these methods the simplest and most promising is the gas phase thermal dissociation of metal carbonyls during a transport reac tion in which the chemical nature of the starting compo nents changes. The formation of small amounts of iron whiskers (IW) from iron pentacarbonyl (IPC) and hydro gen was observed for the first time in a chamber of an electron microscope. 2,3 However, lacking data on the mechanism of metal carbonyl dissociation did not allow a preparative method of α iron IW preparation to develop. The purpose of this work was to search for optimum con ditions of preparing α iron whiskers from iron carbonyls, to reveal the main factors affecting the formation of the structure, chemical and phase compositions of iron whis kers, and to establish a scheme of thermal dissociation of metal carbonyls. ExperimentalIron pentacarbonyl Fe(СО) 5 , iron dodecacarbonyl Fe 3 (СО) 12 , and carbidocarbonyl cluster Fe 5 С(СО) 15 were used as starting compounds for studying thermal dissociation.Industrial IPC was purified by distillation. Iron dodecacarbonyl was synthesized by refluxing IPC and triethylamine in an aqueous solution followed by treatment with hydrochloric acid and purified by washing with water, metha nol, and hexane. 4,5 Iron carbidocarbonyl cluster Fe 5 С(СО) 15 was synthesized according to a previously described procedure. 6,7All carbonyls used are volatile and easily decompose, which makes it possible to significantly decrease the tem perature of thermal dissociation compared to that, e.g., of oxides, to reject the use of explosive and corrosion active me dia (hydrogen, chlorine, etc.), and to use supports of different shapes. Wire and plates of dif...

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“…The structure of the [3] 0 was determined by X-ray crystallography ( Figure 1). Overall, the product consists of Fe 5 C(CO) 13 and Fe(tBuNC) 5 subunits linked by a μ 3 -sulfide. The octahedral SFe(tBuNC) 5 center is assigned as Fe II because it structurally resembles simpler derivatives such as [Fe(SR)(tBuNC) 5 ] + .…”

Section: Redox Transformations Of [Fe 6 C(co) 14 (S)] 2-mentioning

confidence: 99%

Reactions of [Fe₆C(CO)₁₄(S)]²^–: Cluster Growth, Redox, Sulfiding

2020

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Redox reactions, substitutions, and metalations are reported for the iron carbido sulfide [Fe6C(CO)14(S)]2– ([1]2–). Dianion [1]2– oxidized to [Fe6C(CO)16(S)]0 ([2]0) upon treatment with of [Fe(C5H5)2]BF4 or HBF4 (H2 formation) under an atmosphere of CO. Reaction of [2]0 with tBuNC gave [Fe6C(S)(CO)13(tBuNC)5], consisting of Fe5C(CO)13 and [Fe(tBuNC)5]2+ subunits linked by a µ3‐S2–. The Fe7CS cluster [Fe7C(CO)17(S)]2– formed upon treatment of (Ph4P)2[1] with Fe(benzylideneacetone)(CO)3. The Fe7 species is an edge‐fused cluster with [Fe6C(CO)10(µ‐CO)4] and Fe(CO)3 subunits joined by µ3‐S and two Fe–Fe bonds. The analogous reaction using Mo(CO)4(norbornadiene) gave [MoFe6C(CO)18(S)]2–. In this cluster, the Mo center is located in the octahedral subunit. Treatment of [1]2– with SO2 afforded [Fe6C(S)(SO2)(CO)13]2–. This cluster features an Fe6C core decorated with µ3‐S and µ2‐SO2 ligands. These experiments were undertaken in an effort to connect organometallic clusters to FeMoco.

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Metal carbide clusters synthesis systematics for heteronuclear species

Cited by 89 publications

References 2 publications

Metal–metal bonds in biology

Metal–metal bonds in biology

Thermal dissociation of iron carbonyls during growth of iron whiskers

Reactions of [Fe₆C(CO)₁₄(S)]²^–: Cluster Growth, Redox, Sulfiding

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Metal carbide clusters synthesis systematics for heteronuclear species

Cited by 89 publications

References 2 publications

Metal–metal bonds in biology

Metal–metal bonds in biology

Thermal dissociation of iron carbonyls during growth of iron whiskers

Reactions of [Fe6C(CO)14(S)]2–: Cluster Growth, Redox, Sulfiding

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Reactions of [Fe₆C(CO)₁₄(S)]²^–: Cluster Growth, Redox, Sulfiding