Group 12 metals Electron donor-acceptor complexes

They acknowledge that the exact mechanism of the adsorption of heavy metal chelates is quite complex but do not hesitate to propo.se the formation of an electron donor-acceptor complex of the chelate and the active sites (e.g., carbonyl groups) and possible beneficial effect of hydrogen bonding between the... 

The compact size and strong polarity of the nitrile groups make them very interactive with their surroundings. The lone pair orbital on nitrogen is suitable for hydrogen bonding, as well as for electron-donor-acceptor complex formation. In addition, the electrons in the -orbitals of the nitrile triple bond are available for interactions, for example, with transition-metal ions. 

P-donor ligands usually form phosphorus-metal bonds with a main group or transition metal that are essentially covalent and in which the phosphorus is the lone pair donor. Despite the vast number of complexes prepared, often with elaborate architecture, the nature of the phosphorus-metal bond remains elusive and controversial, in particular, for transition metals. The simple statement of the bond as a neutral donor-acceptor complex has been elaborated by identifying the many contributing factors. We will discuss the steric factor and the electronic component of the P-M bond separately. The separation of the electronic component into a and n factors is a formal exercise, the reality being Synergic Bonding, wherein these electronic factors are mutually dependent. 

Organic nitriles, in particular acetonitrile, form stable electron-donor-acceptor (EDA) complexes with a number of Lewis acids such as BX3(X = Cl, Br, 1), SnC, AICI3, and with many transition metal halides, the nitrile group acting as the electron donor ... 

Reactivity studies of two-coordinate chelate group 13 species have Just begun and appear particularly interesting because such species may exhibit both a Lewis acid character (due to the sextet configuration at the metal center) and a Lewis base one (due the lone pair of electrons at the metal center) see Lewis Acids Bases). For instance, the two-coordinate Ga chelate HC(CMeNAr)2 Ga reacts with B(C6F5)3 to form the gallium-boron donor-acceptor complex HC(CMeNAr)2 Ga... 

As a matter of classification, these single bond complexes are divided into three groups according to the number of electrons formally donated by the borane ligand to the metal. The zero-electron donor (or electron pair acceptor) complex is exemplified by the compound Na[(OC)sMn BH3] (J), the one-electron donor by the compound l,2-(CH3)2-3-[(C5H5)Fe(CO)2]-BioC2H9 (2), and the two-electron donor by the compound (CH3)4N[7,8-B9H,oCHPCr(CO)5] (3). 

The catalytic activity of metal ions originates in the formation of a donor-acceptor complex between the cation and the reactant, which must act as a Lewis base. The result of the complexation is that the donor atom becomes effectively more electronegative. All functional groups that have unshared electron pairs are... 

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