Carbonyl Preparation

Many metal carbonyls are available commercially. However, in some cases, the CVD investigator may find it more expedient (and sometimes cheaper) to produce them in-house. This is particularly true of the only two carbonyls that can be obtained by the direct reaction of the metal with CO (and consequently easy to synthesize), i.e., nickel carbonyl, Ni(CO)4, and iron carbonyl, Fe(CO)5. 

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We have reviewed experiments on two classes of systems, namely small metal particles and atoms on oxide surfaces, and Ziegler-Natta model catalysts. We have shown that metal carbonyls prepared in situ by reaction of deposited metal atoms with CO from the gas phase are suitable probes for the environment of the adsorbed metal atoms and thus for the properties of the nucleation site. In addition, examples of the distinct chemical and physical properties of low coordinated metal atoms as compared to regular metal adsorption sites were demonstrated. For the Ziegler-Natta model catalysts it was demonstrated how combination of different surface science methods can help to gain insight into a variety of microscopic properties of surface sites involved in the polymerization reaction. 

The first metal carbonyl prepared was Ni(CO)4, which was obtained by Mond in 1890. This extremely toxic compound was prepared by first reducing nickel oxide with hydrogen,... 

Heteroalkenes, with iron, 6, 132 Heteroannulation, allylic benzylamines, 10, 156 Heteroarene chromium carbonyls, preparation and characteristics, 5, 260 Heteroarenes borylation, 10, 242 C—H functionalizations, 10, 127 as metal vapor synthesis milestone, 1, 237 with titanium, 4, 246 vanadium complexes, 5, 48 7]6-Heteroarenes, with platinum, 8, 664 Heteroaromatic compounds... 

Heck demonstrated Eq. (89) for a number of acylcobalt carbonyls, preparing them from the corresponding alkyl halide and sodium cobalt carbonylate. In the presence of bases, cobalt hydrocarbonyl regenerated cobalt carbonylate ion and a catalytic reaction resulted at atmospheric pressure and at temperatures from 0° to 100° C. Thus the following reaction was reported in 56% yield at 50° C ... 

Stereoisomerization-free synthesis of a dipeptide according to the original DCC procedure (above) or a modified DCC procedure (below) (Z = be nzyloxy carbonyl preparation of compound A Figure 6.29). 

F. Calderazzo, R. Ercoli, and G. Natta, Metal Carbonyls Preparation, Structure, and Properties, in Organic Synthesis via Metal Carbonyls, (Eds. I. Wender and P. Pino, Interscience Publishers, New York, 1968, Vol. I, p. 216). 

Many metal carbonyls prepared in solid noble gases can only be investigated by spectroscopic methods. Vibrational spectroscopy has been a successful tool for probing the structures and bonding of these reactive species. A famous representative of this large group of compounds is Pd(CO)4, which is only stable below 80 K (Moskovits and Ozin, 1976). 

F. Calderazzo, R. Ercoli, and G. Natta Metal carbonyls—preparation, structure and properties, pp. 1-272 (1410). 

Metal Cyanides, Carbides, Carbonyls, and Alkyls Metal carbonyls Preparation and properties... 

Metal carbonyl preparations can be divided into three main categories (1) dry methods, i.e., reactions occurring in the absence of any inert or reactive liquid, (2) wet methods, i.e., reactions occurring in the presence of an inert or reactive liquid, and (3) matrix-isolation techniques (see 14.6.1.5), by which a vaporized metal reacts with CO usually at temperatures around 20K. The latter low T method has been widely used recently for unstable metal carbonyls, their presence being usually established by IR spectroscopy. Examples are Cu(CO)3, AlfCOj, Ti(CO)g, and Ag(CO)2. We deal here only with the conventional methods (1) and (2), which are used almost exclusively for the preparation of thermally stable metal carbonyls. 

Whyman, R., Polynuclear phosphine- and arsine-substituted rhodium carbonyls, preparation of Rh4(CO)iiL (L=PPhs, AsPha, P(p-MeCeH4)3 P(p-FC6H4)s) and Rh4(CO)io(diphos), Chem. Comrnun. p. 230 (1970). 

Sheline and Slater reviewed the IR spectra of lanthanoid and actinoid carbonyls prepared in inert gas matrices. 

A particular difference lies in the organometallic chemistry in low oxidation states. Transition metals form stable binary carbonyls—for example, Fe(CO)s and Ni(CO)4 are volatile liquids, stable at elevated temperatures, and Os3(CO)i2 decomposes at 190 °C to other carbonyls such as Os6(CO)i8. In contrast, lanthanide carbonyls, prepared by cocondensation of lanthanide atoms with Ar/CO mixtures at 4.2 K, are only stable at these very low temperatures, decomposing above 20 K. The ability of metals in the middle of the d block to form carbonyls is related to their possessing vacant d orbitals that can accept electron pairs from the o-donor CO ligand, and also some filled d orbitals that can participate in n back-donations (back-bonding). In fact, CO is not a strong enough r-donor to bind well to lanthanides, and the lanthanide 4f orbitals are not suitable to 7r-bond to carbon monoxide. Molecular orbital (MO) calculations indicate that the bonds in these compounds are very weak indeed. ... 

Condensation of hexafluoropropylene with fluorosulfonylperfiuoroalkyl carbonyl (prepared by electrochemical fluorination of the respective aliphatic sulfone), gives perfluoroether fluorosulfonyl acyl fluorides which are subsequently converted to the vinyl ether. 

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