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Peri–peri interactions in naphthalene systems control the degree of bond formation between a peri-dimethylamino group and a polarised alkene or aldehyde group. Two peri-phenyl groups, which repel, induce closer N⋯C interactions or bond formation, while the ethylene link in the corresponding acenaphthene system has the opposite effect, and for the more electron-deficient alkenes lead to formation of a fused azepine ring initiated by the tert-amino effect. In related 1,8-fluorene derivatives N⋯C interactions occur for an aldehyde and a moderately polarised alkene, but fused azocines are formed when the alkene is more reactive. [ABSTRACT FROM AUTHOR]

The separation between a pair of peri-located dimethylamino and ethene-2,2-dinitrile groups in a naphthalene molecule, which models the progress of a Michael reaction, can be controlled by the installation of a short ethylene bridge or the introduction of repulsive interactions at the opposite set of peri positions. Introduction of a dimethylammonium substituent produced a hydrated chloride salt in which the Me2N⋯C(H)＝C(CN)2 separation between reactive groups decreases, reversibly, from 2.167 Å at 200 K to 1.749 Å at 100 K, with the maximum rate of change in the range 128–140 K, which was studied by variable temperature X-ray crystallography and solid state NMR. From these and other crystallographic data a correlation between Me2N⋯C bond formation and alkene bond breaking was constructed for the first step of an aza-Michael reaction. [ABSTRACT FROM AUTHOR]

A series of TTF and EDT-TTF derived donors bearing thiophene, bithiophene and terthiophene side chains is described, from which a group of six radical cation salts with polyiodide ions were formed and structurally characterised. Typically, they contain complex networks of pentaiodide or triiodide anions or both, in some cases including further iodine, with networks of eight, ten, twelve or sixteen iodine atoms. Donor monocations form face-to-face pairs, but tetrakis-substituted donors are slipped along their main axis so the donor side chains can wrap around each other. [ABSTRACT FROM AUTHOR]

Materials exhibiting both chirality and conductivity do not exist in nature and very few examples have been synthesised. We report here the synthesis of a chiral molecular metal which remains metallic down to at least 4.2 K. This material also exhibits room-temperature switching capabilities with a transition upon cooling below 10 °C. [ABSTRACT FROM AUTHOR]

Oxidation of 1,5-bis(dimethylamino)naphthalene with iodine leads directly to a bis(dimethyliminium) derivative of acridino[2,1,9,8-klmna]acridine, containing six fused six-membered rings, as a bis triiodide salt. The cation has a twisted structure due to the minimisation of peri interactions between each dimethyliminium group and a hydrogen atom. Use of TCNQ as oxidizing agent leads to the same dication as a tetrakis(TCNQ) salt, while use of TCNQ-F4 gave a related monocation which is dimethylated on a ring nitrogen atom. [ABSTRACT FROM AUTHOR]

Methyl 2,6-diaminobenzoate and its bis-triphenylboron complex show hydrogen bonding from NH2 groups to both oxygen atoms of the carboxylic ester, and there is little difference in the lengths of these types of hydrogen bond, while the crystal structure of the tetrafluoroborate salt is dominated by cation/anion hydrogen bonding. In methyl 2-amino-6-tosylaminobenzoate, the more acidic tosyl-N–H group forms a hydrogen bond to the carbonyl and the primary amino group makes a hydrogen bond to the alkoxy group. A search of the Cambridge Structural Database reveals a number of examples of N–H⋯O hydrogen bonding to the alkoxy oxygen of an ester group with a preference for the N–H bond lying in the ester plane. Hydrogen bonding to the ester alkoxy group should not be excluded when considering mechanistic processes in chemical or biochemical systems. [ABSTRACT FROM AUTHOR]

Crystal structures of six 1 : 1 triiodide salts of a series of enantiopure bis(pyrrolo[3,4-d])TTF derivatives, the first structures of radical cation salts reported for this bis(pyrrolo) donor system, show three different arrangements of triiodide ions, organised either in head-to-tail pairs, in infinite lines, or in a castellated arrangement. The complex crystal structures, obtained by electrocrystallisation, are influenced by the presence of solvent, for example changing an ABCABC packing arrangement to ABAB with inclusion of THF, as well as by the size of the chiral side chain. [ABSTRACT FROM AUTHOR]

Two novel enantiopure bis(pyrrolo[3,4-d])tetrathiafulvalene derivatives, substrates for preparing chiral conducting materials, show chiral crystal packing arrangements in which successive layers are rotated in accordance with an exact or approximate 43axis. The corresponding donors containing fused dihydropyrrole groups, and thus four more hydrogen atoms, form stacks along a crystal axis. [ABSTRACT FROM AUTHOR]