Investigation of the kinetics of the chain-radical process in the system iron carbonyl–Lewis base

Belousov, Yu. M.; Brin, E. F.

doi:10.1016/s0277-5387(01)00873-7

Cited by 10 publications

(3 citation statements)

References 22 publications

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“…In addition, the catalytic Bell-Boudoir reaction resulting in contamination of the metallic surface can occur for heavier clusters, while the IW that formed are characterized by high purity. Thus, in the second step α Fe whiskers grow rapidly in length with a rate of 1.5 µm s -1 , which agrees with rather high rates of ICRA clusterization in the liquid (10 3 -10 4 mol L -1 s -1 ) 42 and gas phases (10 -12 -10 -9 cm 3 s -1 ). 44 The rate of chain propagation reactions should de pend on the IPC pressure.…”

Section: Etcsupporting

confidence: 75%

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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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Section: Etcsupporting

confidence: 75%

“…[41][42][43] Activating complexation implies the formation of an active (with the properties of a reducing agent with re spect to a nonactivated molecule of metal carbonyl) orga nometallic compound as a result of the reversible addition of a nucleophilic molecule at one of the carbonyl ligands Nu is nucleophile.…”

Section: Resultsmentioning

confidence: 99%

Thermal dissociation of iron carbonyls during growth of iron whiskers

et al. 2004

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“…There are a number of examples in the literature of addition reactions between iron pentacarbonyl and amines (Sternberg et al 1956;Edgell et al 1965;Edgell and Bulkin 1966), Lewis bases (Belousov and Belousova 1999;Belousov and Brin 2001) and numerous other adducts (Lane et al 1986). In these examples, the nucleophilic adduct concentration is relatively high, with the reaction run in a non-aqueous environment.…”

Section: The Formation and Replication Of Proto-nucleic Acidmentioning

confidence: 99%

A Suggested Pioneer Organism for the Wächtershäuser Origin of Life Hypothesis

Kundell

2010

Orig Life Evol Biosph

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A suggested pioneer organism for the Wächtershäuser origin of life hypothesis is presented. In this scenario, a cubic pyrite crystal edge serves as a catalytic surface for the production of a proto-nucleic acid. Computational analysis demonstrates how the vacant cubic pyrite edge could be populated by iron(II) and hydrogen phosphate, capped with a distorted iron pentacarbonyl. A bridging iron sulfide then forms blocking one side of the edge. The carbonyl on the other side of the edge can then react with either existing uracil or cytosine, to produce a nitrogen-iron carbonyl intermediate. This intermediate serves as a free radical initiator for a polymerization of carbon monoxide and molecular hydrogen. After the fourth carbon is added to the chain, the polymerization is terminated by ring formation yielding a condensed ribose. The resultant product is a proto-nucleic acid, a pioneer organism.

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Mechanisms of Reaction of Organometallic Complexes

Atwood

Rosenberg

2005

Encyclopedia of Inorganic Chemistry

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An overview of the mechanistic features of organometallic reactions is presented. The primary mechanistic types discussed are ligand substitution, oxidative addition, reductive elimination, and electron transfer. Each reaction pathway is discussed within the context of the common electron counts encountered for most organometallic complexes. Examples of how these common reaction pathways extend to polynuclear complexes are also presented. Although reasonable generalizations with regard to overall reaction rates and stepwise mechanisms using the electron count formalism can be made, many recent reports point out that the details of ligand and metal center structure can override these general trends. A considerable amount of quantitative rate data is provided and computational methodologies for understanding the observed rates are discussed.

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Investigation of the kinetics of the chain-radical process in the system iron carbonyl–Lewis base

Cited by 10 publications

References 22 publications

Thermal dissociation of iron carbonyls during growth of iron whiskers

Thermal dissociation of iron carbonyls during growth of iron whiskers

A Suggested Pioneer Organism for the Wächtershäuser Origin of Life Hypothesis

Mechanisms of Reaction of Organometallic Complexes

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