Iron, hexacarbonyl

Wong, Y.S., Paik, Fl.N., Chieh, P.C., and Carty, A.J., Two-carbon three-electron ligands. Phosphonium-betaine complexes via nucleophilic attack by phosphites on a o-rc-acetylide di-iron hexacarbonyl derivative, /. Chem. Soc., Chem. Commun., 309, 1975. 

B2Fe20gCgHg, Iron, hexacarbonyl[p-[hexa-hydrodiborato(2—)]]di-. 29 269 B2Hg, Diborane(6), 27 215 B2NgRuC5gHgg, Ruthenium(II), (t) -1,5-cyclooctadiene)tetrakis(hydrazine)-, bis-[tetraphenylborate(l-)], 26 73 B2NgRuCg( H7g, Ruthenium(II), (ti -1,5-cyclooctadiene)tetrakis(methylhydra-zine)-, bis[tetraphenylborate(l-)],... 

FeOgP2CjgH32, Iron(Il), dicarbonyl-ci> dihydrido-frawj-bisl triphenyl phosphite)-, 29 159 FejBjOjQHg, Iron, hexacarbonyl[p-... 

Ci4HioFe20g, (1,3,5-Cyclo-octatriene) di-iron hexacarbonyl, 34B, 475 Cl4H12Cr04, (5,7-Dimethyl-4H-cyclohepta[b]furan)tricarbonylchromium, 43B, 1108... 

Other examples are iron pentacarbonyl, Fe(CO)s, and chromium hexacarbonyl, Cr(CO)(j, which have trigonal bipyramidal and octahedral configurations respectively. 

The TT-complex 63 was obtained by the condensation of chromium hexacarbonyl with the thiophene a-derivative of dicarbonylironcyclopentadienyl 64 (76IZV153, 79IZV900). The presence of the electron-donor iron-containing substituent facilitates TT-coordination. 

The time resolved spectra produced on excimer laser photolysis of Mn2(CO)io are shown in figure 6. Note that as in the case of iron pentacarbonyl and chromium hexacarbonyl photolysis, there is a distinct increase in the amplitude of the lower frequency absorption bands as the photolysis energy increases. By comparison with the frequency of matrix isolated and solution phase Mn(C0)5, the band at -1996 cm l is assigned to the gas phase Mn(C0)5 radical [33]. This... 

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 transfer of charge from the metal to the ligand caused by back-donation can also be seen from a comparison of the ionization potentials of chromium in different complexes. The ionization potential of complex compounds is higher than that of the uncomplexed coordination center (6.76 eV), e.g. for dibenzenechromium ) 7.07 eV, and for hexacarbonyl-chromium 8.03 eV 43). It may be expected that a decrease in the net positive charge at the coordination center will give rise to an increase in ti-EPD properties. Hence the Fe-C distance will be shorter in [Fe(CO) 4] than in Fe(CO) 5. Likewise iron is more strongly coordinated in ferrocene than in the ferrocinium ion. 

Tungsten hexacarbonyl is produced by heating tungsten metal with carbon monoxide at high pressure. Also, carbonyl can be prepared by reducing the tungsten hexachloride by heating with iron powder under carbon monoxide pressure. 

Many complexes of conjugated ketones are also known, such as the iron tricarbonyl complexes of substituted cyclopentadienones 30), although reaction with chromium hexacarbonyl occurs only if phenyl substituents are available for tt complexing 31). A common difficulty of preparing complexes of heterocyclics is the ability of the heteroatom to form o bonds with the metal. 

Convenient synthesis of chromium and iron phthalocyanines can be achieved by reaction of 1,2-dicyanobenzene with chromium hexacarbonyl or iron pentacarbonyl respectively in refluxing chloronaphthalene (equation 42).232... 

Especially characteristic were the tricarbonyl derivatives M(CO)3L3 (L = amine, NH3, etc.), but tetra- and pentacarbonyl compounds were also discovered. Recently, even dicarbonyls M(CO)2(L—L)2 and fully substituted derivatives M(L—L)3 and M(L—L—L)2 (L—L = dipyridyl, o-phenanthroline L—L—L = tripyridyl) have been synthesized from the hexacarbonyls by my former co-worker H. Behrens (5). Monosubstituted derivatives of iron pentacarbonyl Fe(CO)4L (L = NH3, amines, etc.) have been identified relatively recently (6). 

The reaction, of metal carbonyls with 1,3-diketones generally results in a complete displacement of carbon monoxide accompanied by oxidation of the metal to yield 1,3-diketonato complexes. For example, iron pentacarbonyl, chromium hexa-carbonyl, and molybdenum hexacarbonyl afford FefCgHjOOs,1 Cr(CsHr02)8,2 and Mo(CgH702)s,2,s respectively, when allowed to react with 2,4-pentanedione. 

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