Carbonyls, chromium nickel

The formulas for the metal carbonyls are determined by the number of pairs of electrons needed by the metal to reach the number of electrons in the next noble gas atom. Thus, the stable carbonyl with nickel contains four CO molecules, that with iron contains five, and that with chromium contains six. The bonding in these complexes will be discussed in more detail in Chapter 16. 

FIGURE 21.1 The structures of the mononuclear carbonyls of nickel, iron, and chromium. 

Dodecacarbonyltri-frarngw/o-osmium, 288 Iron carbonyl, 152 Lithium acetyl(carbonyl)nitrosyltris-(triphenylphosphine)cobaltate, 102 Molybdenum carbonyl, 194 Nickel carbonyl, 198 Pentacarbonyl(ethylmethoxymethylene)-chromium, 82... 

Keywords Carbonyl Chromium Decarbonylation Electronic structure Excited state dynamics Iron Mass selective detection Nickel Photophysics Ultrafast electron diffraction... 

Other examples of transition metal carbonyls are nickel tetracarbonyl, Ni(CO)4, a colorless, toxic, flammable liquid that boils at 43°C and chromium hexacarbonyl, Cr(CO)6, a colorless crystal that sublimes readily. Ni(CO)4 is tetrahedral and Cr(CO)6 is octahedral. 

Carbon monoxide is also important in that it is frequently used as synthesis gas (e.g., in methanol synthesis). Under pressure, carbon monoxide attacks unalloyed and low-aUoy steels above 130-140°C, forming iron pentacarbonyl. Above 350°C, corrosion practically ceases again because the carbonyl becomes unstable. In high-alloy chromium and chromium-nickel steels, the damage is appreciably less. Chromium steels with 30% Cr and austenitic steels with 25% Cr and 20% Ni are completely stable. 

Pyridazines form complexes with iodine, iodine monochloride, bromine, nickel(II) ethyl xanthate, iron carbonyls, iron carbonyl and triphenylphosphine, boron trihalides, silver salts, mercury(I) salts, iridium and ruthenium salts, chromium carbonyl and transition metals, and pentammine complexes of osmium(II) and osmium(III) (79ACS(A)125). Pyridazine N- oxide and its methyl and phenyl substituted derivatives form copper complexes (78TL1979). 

Schlatter et al. found that their data with copper chromite agrees better with 0.7 order for CO concentrations (53). For crystals of nickel oxide and chromium oxide, Yu Yao and Kummer have found that the kinetics depend on CO or hydrocarbon around 0.55 order and depend on oxygen around 0.45 order (79). Hertl and Farrauto found evidence that CO adsorbs on copper as a carbonyl group, and adsorbs on chromium oxide as a unidentate carbonate. They found that the kinetics depends on CO to the first order, and depends on oxygen to the zero order (80). 

In a similar vein, we observe nickel(O), possessing ten electrons in its valence shell, to require four carbonyl ligands to satisfy the eighteen electron rule and form [Ni(CO)4l, whilst chromium(O), with six electrons in its valence shell forms [Cr(CO)6]. These latter compounds are tetrahedral and octahedral respectively. 

Many carbonyl and carbonyl metallate complexes of the second and third row, in low oxidation states, are basic in nature and, for this reason, adequate intermediates for the formation of metal— metal bonds of a donor-acceptor nature. Furthermore, the structural similarity and isolobal relationship between the proton and group 11 cations has lead to the synthesis of a high number of cluster complexes with silver—metal bonds.1534"1535 Thus, silver(I) binds to ruthenium,15 1556 osmium,1557-1560 rhodium,1561,1562 iron,1563-1572 cobalt,1573 chromium, molybdenum, or tungsten,1574-1576 rhe-nium, niobium or tantalum, or nickel. Some examples are shown in Figure 17. 

The binary metal carbonyls are named by giving the name of the metal followed by the name carbonyl, with the number of carbonyl groups indicated by the appropriate prefix. For example, Ni(CO)4 is nickel tetracarbonyl, whereas Cr(CO)6 is chromium hexacarbonyl. If more than one metal atom is present, the number is indicated by a prefix. Thus, Co2(CO)8 is dicobalt octacarbonyl, and Fe2(CO)9 has the name diiron nonacarbonyl. 

The mononuclear metal carbonyls contain only one metal atom, and they have comparatively simple structures. For example, nickel tetracarbonyl is tetrahedral. The pentacarbonyls of iron, ruthenium, and osmium are trigonal bipyramidal, whereas the hexacarbonyls of vanadium, chromium, molybdenum, and tungsten are octahedral. These structures are shown in Figure 21.1. 

The work cited in sections 2.4 and 2.5 is representative of the SN1 substitution reactions of metal carbonyls. However, a much more extensive and detailed account has recently been published covering similar reactions of vanadium, chromium, molybdenum, tungsten, rhenium, iron and nickel carbonyls in addition to those of manganese and cobalt2 9a. 

Transition metal complexes which react with diazoalkanes to yield carbene complexes can be catalysts for diazodecomposition (see Section 4.1). In addition to the requirements mentioned above (free coordination site, electrophi-licity), transition metal complexes can catalyze the decomposition of diazoalkanes if the corresponding carbene complexes are capable of transferring the carbene fragment to a substrate with simultaneous regeneration of the original complex. Metal carbonyls of chromium, iron, cobalt, nickel, molybdenum, and tungsten all catalyze the decomposition of diazomethane [493]. Other related catalysts are (CO)5W=C(OMe)Ph [509], [Cp(CO)2Fe(THF)][BF4] [510,511], and (CO)5Cr(COD) [52,512]. These compounds are sufficiently electrophilic to catalyze the decomposition of weakly nucleophilic, acceptor-substituted diazoalkanes. 

XPS Spectrum of Surface. Figure 2 shows XPS spectra of CDC nickel-plated sheets with various pretreatment. Carbon, oxygen, chromium and nickel are observed in the surface of CDC nickel-plated sheets oiled with DOS and ATBC. The carbon spectra show ester carbonyl carbon and hydrocarbon species on both samples. The ester carbonyl carbon reflects the ester bond of DOS (C8Hi7C00C8Hi60C0C8Hi7) and ATBC ((C3H7COO)3C(CH2)OCOCH3). 

Selective catalytic hydrogenation with chromium-promoted Raney nickel is reported (e.g. citral and citronellal to citronellol) NaHCr2(CO)io and KHFe(CO)4 reduction of a/3-unsaturated ketones (e.g. citral to citronellal) has been described (cf. Vol. 7, p. 7). The full paper on selective carbonyl reductions on alumina (Vol. 7, p. 7) has been published." Dehydrogenation of monoterpenoid alcohols over liquid-metal catalysts gives aldehydes and ketones in useful yields. ... 

CjHjS, Thiophene, tetrahydro-gold complexes, 26 85-87 C4H,NO, 2-Propenamide, 2-methyl-nickel complex, 26 205 C4H1()02, Ethane, 1,2-dimethoxy-solvates of chromium, molybdenum, and tungsten carbonyl cyclopentadienyl complexes, 6 343 tungsten complex, 26 50 ytterbium complex, 26 22 C4H i02.NaC5H5, Ethane, 1,2-dimethoxy-compd. with cyclopentadienylsodium, 26 341... 

The action of carbon tetrachloride or a mixture of chlorine with a hydrocarbon or carbon monoxide on the oxide.—H. N. Warren 9 obtained aluminium chloride by heating the oxide to redness with a mixture of petroleum vapour and hydrogen chloride or chlorine, naphthalene chloride or carbon tetrachloride was also used. The bromide was prepared in a similar manner. E. Demarpay used the vapour of carbon tetrachloride, the chlorides of chromium, titanium, niobium, tantalum, zirconium, cobalt, nickel, tungsten, and molybdenum H. Quantin, a mixture of carbon monoxide and chlorine and W. Heap and E. Newbery, carbonyl chloride. 

A number of new methods for the preparation of cyclopropanols from carbonyl derivatives via 1,3-bond formation between the carbonyl and carbons have been developed. 7>ons-2-alkylcyclopropanols are stereoselectively produced from 2- or 3-substituted acrolein upon exposure to chromium(II) chloride in the presence of a catalytic amount of nickel chloride in DMF (equation 56)73. 2,3-Disubstituted acroleins are, in contrast, inert to the chromium reagent. Treatment of / -stannyl carbonyls with titanium(IV) chloride affords cyclopropanols in good yields when the substrates are ketones not bearing j -alkyl... 

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