ISSN:
0020-7608
Keywords:
Chemistry
;
Theoretical, Physical and Computational Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Three-dimensional crystal structures of the charge-transfer complexes of tetrathiafulvalene (TTF) with tetracyanoquinodimethane (TCNQ), (N,N′-dicyanbenzoquinondiimine (DCNQI), and N,N′-dicyan-2,5-dimethyl-1,4-benzoquinondiimine (2,5-Me2-DCNQI) were studied within the ab initio Hartree-Fock crystal orbital approximation using the CRYSTAL92 routine package. A qualitative agreement with the experimental data was achieved, and a definite border between one-electron and many-electron effects in the specific physical properties of the crystals under study was drawn. The calculations led to the tentative conclusion that the true chemical reaction corresponding to the charge transfer in such systems is a two-step transfer of two electrons from the donor's HOMO to the acceptor's LUMO and not only single-electron transfer, as usually believed. Then, whether the system is conductive or semiconductive depends upon the degree of the charge transfer (one, two, or no electrons, respectively). But the final degree of the charge transfer and the density of states on the Fermi level should be determined by many-electron effects. The theoretical approach used in this work seems to be of crucial importance in designing organic crystals with specific physical properties. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 66: 47-68, 1998
Additional Material:
18 Ill.
Type of Medium:
Electronic Resource
