Benzene herringbone structure

Similarly, dithieno[l,2-A4,5-/) ]benzene 45 has completely planar molecular structures packed in a herringbone arrangement <2005JOC10569>. 

Figure 1.20 (a) Limiting types of tt-tt interaction. Note the offset to the face-to-face mode (direct overlap is repulsive), (b) X-ray crystal structure of benzene showing herringbone motif arising from edge-to-face interactions. 

The ef conformation is responsible for the herringbone motif in crystalline benzene and for the crystal structures of other aromatic hydrocarbons [88]. In the gas phase the benzene dimer, (C(jHg)2, also has the ef structure [89]. The benzene dimer in various solvent environments has been successfully modelled [82, 90]. 

The asymmetric compound 38 has a HOMO energy of -5.35 eV, which is smaller than that of 34 and similar to that of 4 [51]. This compound has a herringbone arrangement in the crystal and exhibits high hole mobility of up to 0.41 cm V s and ambient stability. Compound 39 with one more benzene ring has a HOMO energy of -5.11 eV and mobility of 0.13 cm V s [52]. On the other hand, the symmetric compound 40 has a it-stacking structure, and the mobility is relatively low ( 10 cm V s ) [53]. 

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