Tetraiodoethylene: a supramolecular host for Lewis base donors
Bailey, R. D.; Hook, L. L.; Watson, R. P.; Hanks, T. W.; Pennington, W. T. Tetraiodoethylene: a supramolecular host for Lewis base donors. Cryst. Eng. 2000, 3, 155-171.
Tetraiodoethylene (TIE) forms charge transfer complexes with diazine donors through N···I interactions, in which the structure of the complex is very similar to that of TIE. In TIE, two unique molecules form distinct layers and in the complexes the donor molecules take the place of TIE molecules in one of the layers. I···I interactions within the remaining layer of TIE maintain the structure of the layer and yet allow enough flexibility to accommodate a wide variety of donor molecules. Phenazine, quinoxaline, 1,4-€“dicyanobenzene, and 2,2-€²-€“bipyridine all form complexes with TIE which have very similar structures. Phenazine and 2,2-€²-€“bipyridine donors sit on the same inversion center as the TIE molecules they replace, and the donor-·TIE chains run in the (1 1 0) direction. 1,4-€“Dcb-·TIE has a very similar structure to that of the previously determined pyrazine-·TIE complex, but the donor molecules span TIE acceptors in the (1 -ˆ’2 1) direction rather than (1 1 1). The asymmetric environment of the donor sites in quinoxaline result in a very distorted layered structure, and the I-·-·-·I interactions between neighboring TIE molecules are the weakest of those reported here. Decomposition of TIE in its reaction with 2,2-€²-€“bipyridine gave the side product, 2,2-€²-€“bipyridine(H)]I3-·TIE, in which I-·-·-·I interactions link TIE molecules and I3-ˆ’ anions to form a pseudo-€“polyiodide layer.