Metal—carbon monoxide bond strength

These differences in reactions may be attributed to differences in the strength of the metal-carbon monoxide bond in these metal carbonyl derivatives. 

In addition to these two factors which influence the strength of the metal-carbon monoxide bond by clearly affecting the amount of back-bonding or partial double-bonding between the metal atom and the carbon monoxide ligand, there are two other factors which affect the strength of the metal-carbon monoxide bond. 

Tethwisch, D.G. and Dumesic, J.A. (1986) Effect of metal-oxygen bond strength on properties of oxides. 1. Infrared spectroscopy of adsorbed carbon monoxide and carbon dioxide, Langmuir, 2, 73. 

Surface pretreatment also has a marked effect on CO adsorption oxygen and carbon both inhibit carbon monoxide chemisorption and weaken the metal-adsorbate bond strength. Co-adsorbed hydrogen has no observable effects. 

A second type of cluster emission involves molecular species which can be as simple as carbon monoxide or as complicated as the dodecanucleotide mentioned above. In the first case, the CO bond strength is 11 eV, but the interaction with the surface is only about 1 eV. Calculations indicate that this energy difference is sufficient to allow ejection of CO molecules, although 15 percent of them can be dissociated by the ion beam or by energetic metal atoms (6). For such molecular systems it is easy to infer the original atomic configurations of the molecule and to determine the... 

In some cases such information is readily interpreted and understood. For example, carbon monoxide adsorbed on a metal will show strong carbonyl absorptions (v(CO)) in the infra-red region similar to those found in molecular metal carbonyl complexes (See Al.1.3). The exact positions of the absorption, the number of bands and their shapes, can be correlated with the type of binding (to one, or more, metal atoms) and even to the strength of the bonds. 

As discussed above, reduction of metal-metal bonded complexes is common, particularly for carbon monoxide-substituted complexes. The electrochemical potential of these reactions has been widely studied (see Electrochemistry Applications in Inorganic Chemistry). In addition, Meyer has shown that the metal-metal bond strength can be estimated via electrochemical techniques. The results applied to Mn2(CO)io are in agreement with values obtained by other methods and could provide a means of generating a wide range of metal-metal bond strengths. The legs of the electrochemical cycle are shown in equation (99). 

Double insertions of carbon monoxide into the same metal-hydrocarbyl bond [reaction (j)], are doubtful and multiple insertions [reaction (k)] are unknown. This should be attributed to the relatively lower strength of the carbon-carbon bond in a sequence of the type —C(0)—C(0)—, as shown by the available bond energy data . For example, while the carbon-carbon bond strength in ethane is 376 kJ/mol, the corresponding value in MeC(O)—C(0)Me has been evaluated to be 282 kJ/mol... 

The higher metal-carbon bond strength for a third-row metal explains the failure of rhenium to react. Carbon monoxide insertion occurs in the -cyclopentadienyl derivative of rhenium(I), Re(NO) (>7 -C5H5)Me(PMe3) ... 

Pt and Pd Carbonyl Complexes. Prom reactivity measurement with carbon monoxide, Cox et al. [18] determined the relative CO bonding strength to transition metal clusters ... 

Carbon monoxide adsorption offers a unique system for research in fundamental catalytic adsorption studies. On many metals, because of its high stability (bond strength = 256.7 kcal/mole), CO appears to offer an example of one of the most basic, but, in practice, very rare... 

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