Metals iron triad

These six metals located beneath the iron triad on the periodic chart are very much alike. The first three are called the light platinum triad. The heavy platinum triad includes the other two and platinum itself. They are usually found together in nature and are used for similar things. All are shiny and beautiful and they do not tarnish or rust. 

Exclusive formation of silylstyrenes 76 is achieved when the reactions of styrene and 4-substituted styrenes with HSiEt3 are catalyzed by Fe3(CO)i2 or Fe2(CO)9100. Other iron-triad metal carbonyl clusters, Ru3(CO)i2 and Os3(CO)i2, are also highly active catalysts, but a trace amount of hydrosilylation product 77 is detected in the Ru-catalyzed reactions and the Os-catalyzed reactions are accompanied by 3-12% of 77 (equation 31)100. Mononuclear iron carbonyl, Fe(CO)5, is found to be inactive in this reaction100. 

Kinetic studies have shown that electrophilicity in the iron triad is strongly metal dependent with Fe Ru, Os, and the nucleophilic reactivity order is PPh3 > P(0-tBu)3. Adducts 237 (PR3 = phosphites) react with water to give the cyclohexadienyl phosphonate complexes 239. Complex 235 is a effective catalyst for the conversion of phosphites to HP(0)(0R)2 (99,146,147) [Eq. (29)]. In a similar fashion, benzene ruthenium dications... 

Clusters based on homonuclear trimetal units are dominated by those containing transition metals from the iron triad. Clusters constructed on a Co3 framework are the only additional examples in this section. The first cluster to be reported was Co3(CO)9BNEt3 (22). This arises from the reaction of [Co(CO)4] with BBr3 in the presence of NEt3 and is clearly related to the triosmium systems of Shore et al. discussed above (Fig. 7)... 

Group VIII Fe, Ru, Os. Five-coordinated complexes of the iron triad metals M(0) and M(I) undergo oxidative addition with alkyl, aryl and acyl halides to give 6-... 

The Iron Triad, Platinum Group, and Coinage Metals... 

The nearly identical atomic radii of the iron triad—iron, cobalt, and nickel —help explain the similar chemistry of these three elements. The similarities among the platinum group elements in Periods 5 and 6 emphasize the fact that there is little difference between the atomic radii of the elements in these periods in which inner d orbitals are being filled. The coinage metals show the expected similarity among elements in the same group. 

Among the iron triad metals most complexes are iron Tc-allyl adducts from dienes. This may be fortuitous or owing to an electronic property of the heavier elements. The ruthenium diene complex XXIXa shows no tendency to undergo insertion s, but the origin of this may be steric, as indicated by the protonation of (CO)3Ru(butadiene), which goes via complex XXIXb and yields XXXa S ... 

S.4.3 Reactions of propargyl alcohols with metal carbonyl clusters of the iron triad... 

The metal clusters of the iron triad M3(CO)i2, 4 M = Fe, 5 M = Ru, and 6 M = Os, despite being some of the simplest carbonyl clusters known, are fascinating molecules, which still present interesting structural and dynamic problems. Because of their simplicity, they have been, and indeed remain, archetypal molecules for discussions on fluxional mechanisms. The two heavier congeners 5 and 6 have a clearer and less complicated history. In the solid state they are isostructural, and possess... 

Metal Carbon o-Bonds Involving Group 8,9, and 10 Metals 2.1 The Iron Triad... 

Metallocenes of the iron triad and some other cuclopentadienyl complexes undergo metallation reactions of the ring and therefore show aromatic properties as in the acylation reactions. Both metallation and acylation occur more easily than in the case of benzene. 

Spectroscopic studies on metal carbonyl complexes were relatively abundant in 1993. They include Iridium carbonyl complexes investigated via NMR O NMR studies on (mesitylene)M CO)3 complexes (M = Cr, Mo, W) an interesting NMR method for optimizing the study of slow chemical exchange has been announced natural abundance 0 NMR spectra of metal carbonyl clusters of the iron triad . 

Iron, cobalt, and nickel are similar in properties and are sometimes studied together as the iron triad. For example, each is a fairly active metal that reacts with acids to give hydrogen and the -1-2 ions. In addition to the -1-2 ions, the -1-3 ions of the metals also figure prominently in the chemistries of the elements. Explain why these elements are similar. 

Periodic table. Locate the following classes of elements on Table 7.4, page 109 (a) the alkali metals, (b) the halogens, (c) the noble gases, (d) the alkaline earth metals, (e) the iron triad, (f) the rare earth elements, (g) the coinage metals. 

Most of the transition elements do not react with strong acids, such as HCl and H2SO4. Some do have negative standard reduction potentials for the reaction M"+ -I- ne - M, and liberate hydrogen from hydrochloric acid. These include Mn, Cr, and the iron triad. Silver, gold, the palladium triad, and the platinum triad, the so-called noble metals, are especially inert to acids, both to the nonoxidizing species, such as hydrochloric and hydrofluoric acids, and to the oxidizing acids, such as nitric acid. 

The improvement of hydrophilicity by covering the surface on the cathode side or on both sides with a nonconductive inorganic material brought about a significant reduction in the cell voltage. The surfaces of the membrane are covered with thin layers of a porous inorganic material. This material is an oxide, hydroxide, or carbide of the metals of groups 4, 5 and 6 or the iron triad (Fe, Co, Ni) [139], [147]. 

Carbene Complexes of the Group VIII Metals The Iron Triad.— The electrophilic methylene complex [Fe=CHa(Cp) (dppe)]+ has been characterized in solution by and C n.m.r. The iron cyclohepta-trienylidene complexes [Fe(chpt)(CO)2(Cp)] [PFe] (chpt=(27), (28), and (29) have been synthesized and their crystal structures determined chpt=(27), (28). The complex [Fe(CHPh)(CO)a(Cp)] [PF ] readily undergoes benzyli-... 

The Iron Triad.—Mild protonation of the anion [Fe4(CO)u(/t-CO)(/e3-COMe)] yields [Fe4H(CO)i2(i -COMe)], which in turn reacts with strong acid to generate methane from the iy -COMe liquid X-ray crystal structures are reported for both iron complexes. Methods for the s mthesis of triangular metal-cluster complexes containing iUg-alkylidyne ligands have been reported and structures of this tsrpe have been established by X-ray diffraction methods for... 

Unlike the iron triad complexes, cobalt triad compounds, particularly those of Rh and Ir are much more active in hydrosilation catalysis, although the cobalt carbonyl Co2(CO)g has played a very important role in furthering understanding of the catalytic cycle with transition metals. Recently, a simple cobalt salt, CoBr2, in conjunction with added Bu"P, Znl2 and BU4NBH4 was shown to afford 1,4-hydrosilated isoprene (silicon at C-4) in 90% isolated yield, where most metal catalysts derived from Ru, Rh, Pd and Pt usually lead to a mixture of regioisomers. ... 

Kuz ma et al. (1986a) and Lomnitskaya and Kuz ma (1991a) showed that phosphorus behaves as a metallic element in ternary M-M -P systems at low P content (up to 25 at.%), as indicated by the formation of phosphorus solid solutions in binary intermetallic compounds (e.g., Zr2pe, Zr2Co). In ternary compounds phosphorus atoms occupy the same positions as iron triad metals in the structure. At phosphorus contents up to 33.3 at.%, metallic-type chemical bonds occur in the compounds, and there are no P-P contacts. 

Phase diagrams of the Tb-M-P systems provide an opportunity to observe the influence of the M-component on the interaction in R-M-P systems. In Tb-Cr-P system no ternary compounds are formed, in Tb-Fe-P, 2 in Tb-Co-P, 4 in Tb-Ni-P, 9 and in Tb-Cu-P, 4. Since the differences in atomic radii and electronegativity of these transition metals are small, the main influence on the number of compounds formed must be the electronic structure of the metal. The number of compounds increases from Fe to Ni, moreover, these systems are characterized by forming isotypic (ST Zr2Fei2P7) or structurally related compounds (see sect. 2.4). The system Tb-Cu-P strongly differs from iron triad metal-containing systems no isotypic compounds are formed in the Tb-Cu-P and Tb- Fe, Co, Ni -P systems. 

Kuz ma, Yu.B., Ya.F. Lomnitskaya and S.V. Oryshchyn, 1986a, The interaction of phosphorus with transition metals of IVa-Vla group elements and iron triad metals, in Stable and Metastable Phase Equilibria in Metallic Systems, ed. M.E. Drits (Nauka, Moscow) p. 12-18. In Russian. 

The transition elements iron, cobalt, and nickel comprise the iron triad. Iron, with an annual worldwide production of more than 1.1 billion metric tons, is the most important metal in modern civilization. It is widely distributed in Earth s crust at an abundance of 4.7%. The major commercial use of iron is to make steel (see Section 23-3). 

Variability of oxidation state is seen in the iron triad, even if not to the same degree as with vanadium, chromium, and manganese. The -F2 oxidation state is commonly encountered in all three metals. 

The reactions of the iron triad elements are many and varied. The metals are more active than hydrogen and liberate H2(g) from an acidic solution. Hydrated Co and Ni are red and green, respectively. In aqueous solution, Fe " " is pale green and fully hydrated Fe is purple. (Generally, however, solutions of Fe " "(aq) are yellow to brown, but this color probably results from the presence of species formed in the hydrolysis of Fe (aq). Like the hydrolysis of Al " "(aq), described on page 777, that of Fe (aq) produces an acidic solution. 

The iron triad elements (Fe, Co, and Ni) exhibit a variability in oxidation state with +2 the most common. Like other transition elements these metals form compounds with carbon monoxide called metal carbonyls. 

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