Other metals

Other Metals.—Photochemical or thermal displacement of CO from (ij -allyl)Mn(CO)4 with PX3 (X=R or OR) yields ( -allyl)Mn(CO)2(PX3)2 and (rj3.allyl)Mn(CO)(PX 3) 3 complexes. N.m.r. studies of the latter at low temperature indicate a pseudo-octahedral geometry with rram-phosphorus atoms. C studies of ( -allyl)Mn(CO)4 have also been reported, but quadrupole relaxation by the Mn prohibits any determination of the mechanism of fluxionality. Reaction of [V(CO)4L2] with allyl halides yields ( -allyl)V(CO)3L2 complexes (La = diars or arphos). Similar ( j -methylallyl)V(CO)3L2 complexes (La=arphos or dppm) may be prepared by reaction of isoprene with HV(CO)4La isomers with methyl groups in different positions are obtained. Reaction of CpaTaCla with RMgCl yields Cp2Ta(H)(olefin) complexes (olefin=propene, but-l-ene, pent-l-ene, or cyclopentene). The olefin is easily displaced by phosphine, and the complexes react with Ha to give CpaTaHs.  

Rather poorly characterized olefin complexes of have been isolated from reaction of olefins with VCI4 at - 78 °C at higher temperatures, oligomerization, isomerization, and metathesis takes place. Matrix reaction of copper atoms with ethylene yields complexes of the stoicheiometry (CaH4)nCu ( =1—3) and (CaH4)mCua (7M = 4 or 6).  

Contact with metals and metal compounds can cause various types of side effects on and in the skin as specified below. 

It is essential to understand that bioavailability varies between different elemental forms of metals and their salts. That is why some precious metals are well tolerated, whereas their salts are identified as contact allergens. There is a discrepancy between test results obtained with metal salts (in petrolatum) and tests with metal discs, e.g., palladium and tin. 

Three common contact allergens diagnosed by standard patch testing - chromium, cobalt, and nickel - head every list of metal contact sensitivity (Chaps. 66-68). Concerning some of the metals reviewed below, cases of occupational contact dermatitis are rarely seen today or are at least not reported. The reason is probably due to extensive preventive measures, including reduced exposure and automation (Chap. 52). However, even if a contact allergy is acquired non-occupationally, there is always a risk of relapses at renewed exposure in an occupational setting. 

Results from patch tests performed with impure preparations and with an insufficient number of controls for irritancy imply that some anecdotal reports on contact allergy to metals, such as antimony, iron, lead, silver, manganese, and zinc, may be questioned. Scientifically, as well as from a clinical point of view, it is somewhat challenging that nickel, chromium, and cobalt are so dominant, while the other metals in the periodic table of elements play such a minor role. 

For some metals, testing in guinea pigs has demonstrated allergenic potential but, so far, no clinical case of allergic contact dermatitis has been reported. The potential to cause contact allergy (hazard identifica- 

Zirconium (Zr) is another reactive metal, but its extreme spark sensitivity is a major problem restricting its wider use in high-energy compositions. Zirconium in combination with potassium perchlorate (ZPP composition) is being used as an igniter material in electrically fired systems, and zirconium with iron(Ill) oxide is used in the military 

AlA ignition composition. Flame temperatures of oxidizer-zirconium compositions typically exceed 4,000°C. If you want a really hot pyrotechnic composition—to light another energetic material very quickly—zirconium is the fuel of choice. 

The spade sensitivity of fine zirconium by itself— without any oxidizer present—is usually less than 1 millijoule of spark energy, again putting zirconium compositions in a class by themselves. It makes no difference if the oxidizer is iron(III) oxide or potassium perchlorate, the resulting composition with zirconium will be very spark sensitive. Therefore, zirconium is usually shipped wet, blended wet with oxidizer, and is finally allowed to dry when the composition has been incorporated in small amounts on bridgewires for electrical ignition or in other similar systems. 

In summary, zirconium-oxidizer mixtures will be very sensitive to spark, and they will react very quickly to produce high-temperature sparks ideal for ignition compositions. When you need to light something very quickly with high reliability, these might be materials you would choose. Otherwise, the sensitivity hazards of zirconium preclude wider use of the material. 

Several readily oxidized nonmetalUc elements have found widespread use in the field of pyrotechnics. The requirements again are stability to air and moistme, good heat per gram output, and reasonable cost. Materials in common use include sulfur, boron, silicon, and phosphorus. Their properties are summarized in Table 3.5. 

The above descriptions of the behaviours of various metals is not intended to be comprehensive but is instead intended to give some picture of the complexity of the chemistry of such systems. It is no longer possible to compare the behaviour of different metals without regard to the way in which the catalyst is prepared. The catalyst s formulation (and even its pretreatment) is critical in determining its behaviour. Each study of a particular system must be backed up by a careful characterization of the catalyst concerned in particular, before worthwhile comparisons can be made, reliable determinations of metallic surface areas have to be carried out. 

Only lead and tin will be discussed here. Contact with these metals should be avoided, because in humid media, they may lead to severe galvanic corrosion of aluminium. 

Red lead-based paints or paints containing mercury salts (which are now forbidden by regulations) or copper salts should never be used on aluminium structures. 

Nickel can enter natural waters primarily from wastewaters discharged from plants involved in the surface finishing of metals. 

Organically bonded cobalt occurs in the sludge from biological wastewater treatment plants in the form of vitamin Bj2. 

Molybdenum can be toxic at higher concentrations. It is intensively accumulated by plants. 

Most of the elements of the periodic system occur in waters, including the elements of rate earths. However, these concentrations are very low and do not cause any hygienic or technological problems. Recently, attention has been paid to the remarkable toxicity of beryllium. The compounds of beryllium are used in the production of rocket fuels, fluorescent lamps and they occur in wastewaters from beryllium processing works. 

Aluminium species are oxidation state (III). In aqueous solution, the simple ion exists as Al(H20)g . This ion readily dissociates to give other ions such as A1(H20)50H, all of which are colorless. Over a wide pH range under physiological conditions in alkaline solution, the species appear to be Al(OH)2+, Al(OH)3, AKOH), AlalOH) ]-, AlelOHlf, and AlglOH) . Study of the substitutions of aluminum aqua ion by ligands such as SO , citrate, and EDTA has been established by Al NMR spectroscopy [72]. 

A novel study on the speciation of aluminum in solution has been reported recently by Bertsch et al. [73]. Fluoro, oxalato, and citrato aluminum complexes were identified as distinct peaks together with free Al(III). Post-column reactionAJV detection was used. These studies were used in kinetic, ion exchange, and toxicological investigations. 

Gold cyanide complexes are important in gold plating baths. As the Au(III) bath content increases, the plating efficiency is decreased. Mo- 

Solution VQ2+ (3.5), VOCl -orV03 (1.2) 7.5 mM trilithium citrate, 10 mM oxalic acid 

Solution n-butylsSn (5.5), ethylaSn (9), methylsSn (19) 42 mM NH4 acetate, pH 5.3, 60/40 methanol/water 

Lead and mercury account for most of the literature on the behavioral toxicity of metals vvdth lead generating the most intense debates about public policy and biological mechanisms. Yet as Table 1 demonstrates other metals also are toxicologically as well as biologically important. They have not except for scattered reports received the searching evaluations available through advanced behavioral technology. 

Two developments led neuroscientists as well to reexamine aluminum as a potential neurotoxicant. One was the discovery that aluminum played a role in the encephalopathy associated with kidney dialysis. The other was the implication that it was associated with senile dementia of the Alzheimer type. The connection with dialysis encephalopathy has been established, although a suitable animal model is lacking. The association with Alzheimer s disease is tenuous, but the issue has stimulated a considerable body of work that both illuminates the biological actions of aluminum and provides further knowledge of degenerative processes in the nervous system. The behavioral data in laboratory animals are ambiguous because, to achieve effects, many experimenters have administered the aluminum intracranially, a mode of administration with obvious pitfalls. A useful summary of the recent literature appears in the volume edited by Liss.  

The demonstration that these manifestations respond favorably to L-dopa treatment incited the interest of neurochemists and pharmacologists. The literature now contains many demonstra- 

Of the other metals, only few reports of experimental work are available, although clinical publications abound. There is no doubt that the capacity for neurotoxic damage is more widespread than previously had been believed, but the conditions, such as trace metal balance, supporting such effects need to be defined. 

The preparation of this chapter was supported in part by grants ES-01247 and ES-01248 from the National Institute of Environmental Health Sciences and in part under Contract No. DE-AC02-76EV03490 with the U.S. Department of Energy at the University of Rochester Department of Radiation Biology and Biophysics and has been assigned Report No. UR-3490-2203. 

There is concern that elevated environmental levels of manganese resulting, for example, from the introduction Mn-containing additives to petrol, might be associated with neurological disease. Direct EPR spectroscopy has been used to monitor Mn(II) following the addition of Mn(II) and Mn(III) complexes to human blood plasma and cell lysates.49 

Several nickel catalysts for the carbonylation of methanol have been reported, including an IR study [24], The carbonylation of MeOH to form MeOAc and HOAc was studied using phosphine modified Nil2 as the metal catalyst precursor. The reaction was monitored using a high pressure, high temperature, in situ Cylindrical Internal Reflectance FTIR reactor [25], 

The reaction of alcohols with CO can also be catalysed by palladium iodides, and various ligands or solvents. Acetic acid is prepared by the reaction of MeOH with CO in the presence of a catalyst system comprising a palladium compound, an ionic iodide compound, a sulfone solvent at conditions similar to those of the rhodium system (180 °C, 60 bar), and, in some cases, traces of a nickel-bipyridine compound were added. Sulfones or phosphine oxides play a stabilising role in preventing metal precipitation [26], Palladium(II) salts catalyse the carbonylation of methyl iodide in methanol to methyl acetate in the presence of an excess of iodide, even without amine or phosphine co-ligands platinum(II) salts are less effective [27], 

1 Hallman, N. Hinnenkamp, J. Client. Ind. 2001,82 (Catalysis of Organic Reactions), 545. 

8 Wright, A. P. Abstracts of Papers, 222nd ACS National Meeting, Chicago, IL, U. S. August 26-30,2001 CATL-044. Chem.Abstr. AN 2001 637430. 

16 Thomas, C. M. Mafua, R. Therrien, B. Rusanov, E. Stoeckli-Evans, H. Suss-Fink, G. Chem. Eur. J. 2002,8, 3343. 

NMR spectroscopy has beat used to probe the nature of the cojqier-alkene bond in copper-alkene complexes containing hexafluoroacetone ligands 2. The (t]3.c3Hs) moiety has been identified adsorbed on the surface of Ag(llO) and shown to dimerise to hexa-l,S-diene on the surface 33. The crystal structure of [ Y(Tl3-C3H5)(N(SiMe2CH2PMe2)2))2(M--Cl)2], which contains the highly fluxional yttrium-allyl moiety, has been reported .  

Reaction of but-2-yne with [(RNH)(RN=)2V(OEt2)] (R = Bu 3Si) resulted 33 in displacement of the diethyl ether ligand and formation of [(RNH)(RN=)V C(Me =C(Me)N(R))l which underwent ligand metallation to afford the ri -i-azaallyl complex (15). The synthesis and reactions of the 16-electron bis-(Ti3-allyl) tantalum species [Cp Ta( n3.phCHCHCH2)2] have been reported 34 and the X-ray crystal structure determined 35. 

Pt(PR2)2 complexes catalyse the reaction of ReH, (PR2)2 complexes [PR = PPhPr2, P(cyolopentyl)with C2H to give ReH, (C2H ) 2 (PR3) 2 which affords ReHg(C2H ) (PR3)2 treatment with H, 

CpTi(allyl), and CpV(allyl), have been prepared by reaction of ftl 

Cocoddensation of Cu and Au atoms with propene (L) yields both 

The molecular structure of [Ru(CO)2(PPh3)(n -cod)] has been crystallographically determined. The fluxionality of [Fe(CO)3(n -nbd)] in the CO enriched complex has been investigated by variable temperature IR spectroscopy . The 

NCCH=CH2, NC(He)C CH2, NCCHsCHHe, NCCH2CHBCH2 complexes has been prepared and their reactions and catalytic activity studied .  

A number of water soluble [RhCl(Ph2P(CH2)nl e3 (n nbd)]X (n = 2, 3, 6, 10 X Cl, MO3, PF6) complexes have been prepared auid the molecular structure for n = 2, X PFe was crystallographlcally characterised . The X-ray crystal structure of [Ir PMe(Wi)-C6H40Me-2 2 ( n cod) ] was crystallographlcally determined . The synthesis and molecular structure (for H Rh) of [M(dppmS2)-(n cod)][CIO4] dppmS2 bis(dlphenylphosphino)methane 

The preparation and X-ray crystal structures of [Ir(Ti -trisS3)-(n -cod)] TrisSa = tris(diphenylthiophosphinoyl)methanido)and [Rh [Ph2P(0) l2[Ph2P(S) ]C) (Ti -cod) ]. PrOH have been reported. 

Pd and Pt. - The molecular structure of (12) has been crystallographically determined. An esr study of [Pd(ti -l,5-dibenzocyclooctatetraene) (-n -CsPhs) 1 has been made 

Cyclic and acyclic [CpMn (CO) 2(11 allyl)] complexes may be prepared by protonation of the free double bond of CpMn(CO)2(n -cyclohexadlene) or protonation of CpMn(CO)3(n -allyl-alcohol) complexes addition of PR3 occurs at the allyl ligand to 

C-C bond formation to give a mixture of isomers such as (43) in 

3- dimethylbutadiene gives (PPh )2 61 2(n -2,3-dimethylbutadiene), though use of the chelated derivative (dppe)ReH yields instead 

Cp-V reacts with activated olefins such as acrylonitrile to 2 

A variety of [L2Cu(n -olefin]CIO complexes have been 

The synthesis of [Cp2Ti(T 3-aUyl)] complexes having a variety of substituents on the allyl moieties has been reportedi and the compounds shown to react with carbon dioxide to give single P,y-unsaturated carboxylic acids of a few possible regioisomeric products aftra- hydrolytic work-up of the titanium carboxylates. 

The crystal structure of the cationic zirconium benzyl complex [Cp Zr(CH2Ph)2] [B(CH2Ph)(C6F5)3]- has been reported and it was demonstrated that no cation-anion bonding exists, resulting in remarkable structural features in the highly electr(q)liilic naked cation, including an unprecedented r -benzyl coordination. 

It was reported that one of the trimethylphosphine ligands in the vanadium(III) imido complex [CpV(NAr)(PMe3)2] (Ar = 2,6-C6H3Pr 2) could be substituted with ethene or diphenylethyne to afford complexes of the type [CpV(NAr)(PMe3)(T 2-L)]. Spectroscopic data were consistent with considerable back-donation from the vanadium(m) centres to the alkene and alkyne ligands. Photolysis of a mixture of tri-fcrt-butylcyclopropenium tetrafluoroborate and sodium hexacarbonylvanadate afforded the structurally characterised complex [(C3But3)V(CO)4], which represented the first example of partial insertion of an early transition metal atom into a cyclopropenyl ring. 

The niobium hydrido styrene complex tNb Ti5-C5H4SiMe3)2(H)(Ti2-PhCH=CH2)] has been prepared both from the reaction of [Nb(Ti -C5H4SiMe3)2(H)3] with styrene and from that of [Nb(Ti5-C5H4SiMe3)2Cl2] with [PhCH2CH2MgBr]. The first method gives rise to two isomeric products (endo, where the alkene substituent is central and exo, with the alkene substituent lateral in the equatorial plane), whilst the latter leiuls exclusively to the endo isomer. 

The photochemical generation of polymer-bound [CpMn(CO)2(il2-C=C)] complexes in polyethylene film has been reported and shown to represent a diagnostic probe for investigating the unsaturation of the polymer. 

Complexes of structure (51) have been prepared by either reaction of HVfCO) with the cycloalkadiene or reaction of Na[V(CO) ] with a 3-halo-cycloalkene reaction with PPha yields both mono- and di-substituted derivatives. Syn-anti proton exchange in M( -allyl)4 and (cot)M( y -allyl)2 (M=Zr, Hf) probably occurs by a n-ya- 7i rearrangement activation energies are 6.5 and 11.4 kcal mol , respectively, where M = Hf and 15.2 and 9.1 kcal mol S respectively, where M = Zr.  

Reaction of Cp2NbCl2 with n-CsH MgCl yields the endb-hydride olefin complex (52a R = Me), although with other Grignards, the exo-isomer (52b) may also be formed. Treatment of the endb-complex with CO or RNC L) results in insertion to give derivatives of the type Cp2Nb(L)(alkyl), a reaction which is also observed with the Cp2Ta(H)( -olefin) complexes. - 

The reaction between [Cp2ZrCl2] and either EtMgCl or Et2Mg-dioxane has been investigated and complexes 49 and 50 have been obtained in the latter the alkene was best described as a C2H/ anion. The energy profile for ansa-bridged zirconocene Ziegler-Natta catalysis was obtained from experimental rate data. The Zr and Hf complexes 51 have been prepared and shown to polymerise ethene in the presence of The Zr complex 52 has been 

Reactivation of this compound could be achieved through exchange with Al-cocatalysts the presence of borane activators (through alkene insertion into the Zr-allyl bond) or reaction with H2. DFT calculations suggested that reactivation by H2 was the lo west-energy path way NMR evidence has been 

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Of little use commercially except as a route to anthraquinone. For this purpose it is oxidized with acid potassium dichromate solution, or better, by a catalytic air oxidation at 180-280 C, using vanadates or other metal oxide catalysts. 

Enzymes often need for their activity the presence of a non-protein portion, which may be closely combined with the protein, in which case it is called a prosthetic group, or more loosely associated, in which case it is a coenzyme. Certain metals may be combined with the enzyme such as copper in ascorbic oxidase and selenium in glutathione peroxidase. Often the presence of other metals in solution, such as magnesium, are necessary for the action of particular enzymes. 

S-hydroxyquinoline, oxine, C9H7ON. Light brown needles, m.p. 15-16 C. Forms insoluble complexes with metals. The solubilities of the derivatives vary with pH, etc. and hence oxine is widely used in analysis. Used for estimating Mg, Al, Zn and many other metals. Many oxinates are extracted and the metal is estimated spectrophotometrically. Derivatives, e.g. 2-meIhyl tend to be specific, for, e.g.. Copper derivatives are used as fungicides. 

Iron oxides react with other metal oxides to give ferrates. ... 

Soaps of other metals such as aluminium, calcium, cobalt, lithium, lead or zinc - see metallic soaps. European production 1976 toilet soap 307 000 tonnes, household soaps c. 140000 tonnes, soap powders c. 35000 tonnes. 

For the inspection of other metallic materials, the requirements of inspection classes SA and SB are shown in table 3a and 3b. For weld inspection the inspection classes SA and SB are based on the requirements of EN 462 and EN 1435. 

It is necessary that the mercury or other metallic surface be polarized, that is, that there be essentially no current flow across the interface. In this way no chemical changes occur, and the electrocapillary effect is entirely associated with potential changes at the interface and corresponding changes in the adsorbed layer and diffuse layer. 

Aluminium is obtained on a large scale by the electrolysis of the oxide, dissolved in fused cryolite The oxide, occurring naturally as bauxite, AI2O3.2H2O, usually contains silica and iron(III) oxide as impurities. These must be removed first, since aluminium, once prepared, cannot be freed of other metals (which will be deposited on electrolysis) by refining it. The crude oxide is dissolved under pressure in caustic soda solution the aluminium oxide and silica dissolve and the ironflll) oxide is left ... 

Intermetallic compounds with gallium are used as semiconductors. Indium is used to coat other metals to protect against corrosion, especially in engine bearings it is also a constituent of low-metal alloys used in safety sprinklers. The toxicity of thallium compounds has limited the use of the metal, but it does find use as a constituent of high-endurance alloys for bearings. 

Before this treatment, the cassiterite content of the ore is increased by removing impurities such as clay, by washing and by roasting which drives off oxides of arsenic and sulphur. The crude tin obtained is often contaminated with iron and other metals. It is, therefore, remelted on an inclined hearth the easily fusible tin melts away, leaving behind the less fusible impurities. The molten tin is finally stirred to bring it into intimate contact with air. Any remaining metal impurities are thereby oxidised to form a scum tin dross ) on the surface and this can be skimmed off Very pure tin can be obtained by zone refining. 

Crude lead contains traces of a number of metals. The desilvering of lead is considered later under silver (Chapter 14). Other metallic impurities are removed by remelting under controlled conditions when arsenic and antimony form a scum of lead(II) arsenate and antimonate on the surface while copper forms an infusible alloy which also takes up any sulphur, and also appears on the surface. The removal of bismuth, a valuable by-product, from lead is accomplished by making the crude lead the anode in an electrolytic bath consisting of a solution of lead in fluorosilicic acid. Gelatin is added so that a smooth coherent deposit of lead is obtained on the pure lead cathode when the current is passed. The impurities here (i.e. all other metals) form a sludge in the electrolytic bath and are not deposited on the cathode. 

The nitrates of other metals give nitrogen dioxide, oxygen and the metal oxide, unless the latter is unstable to heat, in which case the metal and oxygen are formed (for example from nitrates of silver and mercury) ... 

Notice that the acidic character is associated with the ability of aluminium to increase its covalency from three in the oxide to six in the hydroxoaluminate ion, [Al(OH)g] the same abihty to increase covalency is found in other metals whose oxides are amphoteric, for example... 

Hydrochloric acid is a strong monobasic acid, dissolving metals to form salt and evolving hydrogen. The reaction may be slow if the chloride formed is insoluble (for example lead and silver are attacked very slowly). The rate of attack on a metal also depends on concentration thus aluminium is attacked most rapidly by 9 M hydrochloric acid, while with other metals such as zinc or iron, more dilute acid is best. 

Cobalt compounds have been in use for centuries, notably as pigments ( cobalt blue ) in glass and porcelain (a double silicate of cobalt and potassium) the metal itself has been produced on an industrial scale only during the twentieth century. Cobalt is relatively uncommon but widely distributed it occurs biologically in vitamin B12 (a complex of cobalt(III) in which the cobalt is bonded octahedrally to nitrogen atoms and the carbon atom of a CN group). In its ores, it is usually in combination with sulphur or arsenic, and other metals, notably copper and silver, are often present. Extraction is carried out by a process essentially similar to that used for iron, but is complicate because of the need to remove arsenic and other metals. 

Mercury has been known for many centuries, perhaps because its extraction is easy it has an almost unique appearance, it readily displaces gold from its ores and it forms amalgams with many other metals—all properties which caused the alchemists to regard it as one of the fundamental substances. 

The metal is slowly oxidised by air at its boiling point, to give red mercury(II) oxide it is attacked by the halogens (which cannoi therefore be collected over mercury) and by nitric acid. (The reactivity of mercury towards acids is further considered on pp. 436, 438.) It forms amalgams—liquid or solid—with many other metals these find uses as reducing agents (for example with sodium, zinc) and as dental fillings (for example with silver, tin or copper). 

However, where small quantities of liquids are involved, a column filled with glass helices will probably give the best results and the cost will not be unduly high. Rings in stainless steel and other metals can be purchased in sizes from to i. ... 

It is also used as a reducing agent in the production of pure uranium and other metals from their salts. The hydroxide (milk of magnesia), chloride, sulfate (Epsom salts), and citrate are used in medicine. Dead-burned magnesite is employed for refractory purposes such as brick and liners in furnaces and converters. 

As with other metals of the alkali group, it decomposes in water with the evolution of hydrogen. It catches fire spontaneously on water. Potassium and its salts impart a violet color to flames. 

The metal is employed to form numerous alloys with other metals. Brass, nickel silver, typewriter metal, commercial bronze, spring bronze, German silver, soft solder, and aluminum solder are some of the more important alloys. 

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