donor-acceptor interaction otherwise coordination bond; charge transfer (rus. взаимодействие, донорно-акцепторное otherwise донорно-акцепторная связь; координационная связь; пернос заряда) — interaction based on charge transfer or transfer of a pair of electrons from the donor to the acceptor.

Description

The donor-acceptor interaction could be considered as charge transfer between the donor and acceptor molecules without the formation of a chemical bond between them and the transfer of a lone pair of electrons from the donor to the acceptor, resulting in the formation of a bond.

In the first case it may refer, for example, to organic donors, in particular, the -donors, such as tetrakis(dimethylamino)ethylene (TDAE), other unsaturated amino compounds, metallocenes, etc., and organic acceptors such as fullerenes or quinodimethanes with acceptor substituents. The interaction of these compounds results in the formation of a charge-transfer complex in which a negatively charged acceptor and positively charged donor interact electrostatically. An important role is played by such systems where only partial charge transfer is observed in the electronic ground state, while the state with almost complete charge transfer can be obtained by photoexcitation. Such systems, donor-acceptor dyads and triads, in which a bridge group is introduced between the donor and the acceptor to improve the lifetime of the charge transfer state, can be used to create devices for solar energy converting (see, for example, artificial photosynthesis). Generally, the charge transfer, in its various forms, plays a key role in many biological processes.

In the second case, the donor and the acceptor are a Lewis acid and a Lewis base, respectively. If the normal covalent bond between two atoms is due to the formation of a common pair of electrons – one from each atom – the donor-acceptor bond is formed by an electron pair of the donor and a free (unfilled) orbital of the acceptor. This kind of donor-acceptor interaction is the main method of forming complex compounds (see Fig.). Such interaction is responsible for many acid-base transformations associated with the transfer of the hydrogen ion (acceptor), and for the formation of supramolecular nanostructures.

Illustrations

Generation of donor-acceptor bonds in Co(NH
Generation of donor-acceptor bonds in Co(NH3)63+ complex. When a Cr3+ ion develops, three additional vacant orbital's appear (two — 3d and one — 4s) that, together with the 4p-orbitals, become filled with six pairs of electrons from NH3 molecules involved in generation of this complex.

Author

  • Eremin Vadim V.

Source

  1. Donor-acceptor interaction // Chemical encyclopedia (in Russian). V. 2. — M.: Sovetskaja ehnciklopedija, 1990. p. 463–464.

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