Bonding between metal atoms and organic

BONDING BETWEEN METAL ATOMS AND ORGANIC n SYSTEMS... 

Bonding Between Metal Atoms and Organic n Systems 483... 

Bonding between Metal Atoms and Organic Pi Systems... 

Bonding between Metal Atoms and Organic Pi Systems 507 TABLE 13.4 Comparative Data for Selected Metallocenes... 

Far-IR (200-10 cm ) especially useful for studies of inorganic matter, because the absorptions related to stretching vibrations and angular deformations of bonds between metallic atoms and other organic and inorganic bonds are observed at frequencies lower than 600 cm . ... 

The results of this DFT study confirm that aluminium and PT oligomers interact preferentially through the formation of covalent bonds between Al-atoms and the a-carbons of thiophene rings. This type of reaction is expected to take place when A1 is deposited on the polymer layer as well as when PT is adsorbed on the metal surface. In all cases, the formation of the Al-C bonds and the geometric modifications induced in the organic molecules lead to important changes in the vibrational spectra which should allow the experimental detection of the vibrational signatures of the species formed at the Al-PT interface. 

The bonding between carbon monoxide and transition-metal atoms is particularly important because transition metals, whether deposited on soHd supports or present as discrete complexes, are required as catalysts for the reaction between carbon monoxide and most organic molecules. A metal—carbon ( -bond forms by overlapping of metal orbitals with orbitals on carbon. Multiple-bond character between the metal and carbon occurs through formation of a metal-to-CO TT-bond by overlap of metal-i -TT orbitals with empty antibonding orbitals of carbon monoxide (Fig. 1). 

Studies of organometaUic compounds show a complete analogy between hydrogen bonding with the participation of d-electrons in metal atoms and sp-electrons in heteroatoms in regular organic bases. For example, in the context... 

Metalorganic A compound containing one or more chemical bonds between a metal atom and the carbon atoms of an organic radical, e.g., (CH3)3Ga these compounds are also known as metal alkyls or organometallics... 

A second basic interaction pathway between transition metal complexes and organic substrates is SET (Path B). The overall processes can involve one individual or several sequential SET steps. For the latter, timing and direction of SET steps determine the reaction outcome significantly. The catalyzed reaction can proceed either as redox-neutral processes, in which oxidative and reductive SET steps are involved in the catalytic cycle, or as overall oxidative or reductive catalytic reactions, where two oxidative or reductive SET steps occur consecutively in the catalytic cycle. The third pathway (Path C) consists of a direct atom or group abstraction by the metal complex, which is possible for a weak R-X bond. 

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