Abstract:1,10-Diiodophenanthrene, prepared for the first time by reacting I 2 with dilithiophenanthrene, has a twist angle w(I´´´C ± C´´´I) 638 between the two iodine centers and a distance d I´´´I 3.61 , which amounts to only 84 % of the sum of van der Waals radii, 2r ) have also been determined. Density functional B3LYP calculations with 6-31G** basis sets and 31G* effective pseudopotentials for iodine provide information on an unexpectedly balanced charge distribution, leading to estimates of about 30 kJ mol À1for the I/I repulsion and of about 10 kJ mol À1 for the reduced p delocalization in the extremely twisted skeleton of 1,10-diiodophenanthrene.

Crystalline supramolecular aggregates consisting of charged organic molecules, held together through metal-cluster-mediated Coulomb interactions, have attracted interest owing to their unusual structural, chemical and electronic properties. Aggregates containing metal cation clusters 'wrapped' by lipophilic molecular anions have, for example, been shown to be kinetically stable and soluble in nonpolar liquids such as saturated hydrocarbons. The formation of supramolecular aggregates can even be exploited to generate aromatic hydrocarbons that carry four negative charges and crystallize in the form of organic poly(metal cation) clusters or helical polymers. Here we report the anaerobic crystallization of an ionic organic aggregate--a contact ion septuple consisting of a fourfold negatively charged 'tripledecker' of three anthracene molecules bridged by four solvated potassium cations. Its electronic ground state is shown experimentally, using temperature-dependent electron paramagnetic resonance spectroscopy, to be a triplet. Although the spins in this biradical ionic solid are separated by a considerable distance, density functional theory calculations indicate that the triplet ground state is 84 kJ mol(-1) more stable than the first excited singlet state. We expect that the successful crystallization of the ionic solid we report here, and that of a covalent organic compound with a triplet ground state at room temperature, will stimulate further attempts to develop new triplet-ground-state materials for practical use.

Partly solvent-separated and partly solvent-shared, the contact ion triple of the 9,10-diphenyltetrabenz[a,c,h,j]anthracene dianion is formed by the ultrasonically activated reaction of hexaphenylbenzene with lithium metal powder in 1,2-dimethoxyethane (dme) [Eq. (1)]. The proposed microscopic pathway for this reaction-twofold dehydrogenation and C-C bond formation-is supported by quantum-chemical calculations.

No abstract

Sodium metal mirror reduction of biphenylene in aprotic THF solution containing [2.2.1]cryptand yields as a structurally characterized product the 9,9dimethylsilafluorene radical anion salt containing a (H 3 C) 2 Si expanded cyclobutadiene ring. In addition, the Si content can be detected by total reflection X-ray (TXRF) analysis. When the use of any silicon grease was avoided for all glass fittings, the solvent-separated biphenylene radical anion contact pair crystallized from an aprotic diglyme solution.