2,5-Dibromothiophenes: Halogen Bond Involving Packing Patterns and Their Relevance to Solid-State Polymerization

Abstract

A series of 2,5-dibromo-3-R-thiophenes (R = COONa 1, CN 2, CONH2 3, CON­(H)­Me 4, CON­(H)­Bn 5, CON­(CH2CH2)2O 6, CON­(H)­NH2 7, CON­(H)­OH 8) were prepared and studied via high-resolution ESI-MS, 1H and 13C­{H} NMR, IR, and X-ray diffraction. The analysis of the X-ray structures revealed Br···Br halogen bonds (XBs) as structure-directing interactions. A search of the Cambridge Structural Database showed an additional 12 structures of 2,5-dibromothiophenes whose structures featured Br···Br XBs. The crystal packing patterns for all these 2,5-dibromothiophenes were classified, and three general types were identified: (i) chains held by XBs, where each Br acts either as an XB donor or as an XB acceptor; (ii) zigzag arrays, where each Br functions simultaneously as an XB donor and acceptor; and (iii) rhombic assemblies with Br atoms at each vertex. DFT calculations, followed by topological analyses of the electron density distribution (QTAIM analysis) at the M06-2X/DZP-DKH level of theory, were performed to evaluate the strength of these XBs. The established energies were in the range from 0.5 to 2.2 kcal/mol, regardless of the packing type.

4,5-Diiodo-1-H-imidazole-derived linker ligand and Cu(i) and Co(ii) coordination polymers based thereupon

“…For the in-depth analysis of halogen⋯halogen interactions in 1–3 , we utilized an approach that is extensively used in the evaluation of non-covalent interactions in coordination compounds: 20,64–69 experimentally determined atomic coordinates were extracted from the X-ray diffraction data and used in DFT calculations “as is” (see ESI† for further details). Results are summarized in Table 1 (the expanded version is given in the ESI†).…”

Halogen Bonding in Halothiophene Building Blocks

“…Halogen bonding (XB), a promising tool and more recent addition to the noncovalent interaction toolbox has gained a great deal of attention , as an equivalent and alternative to the ubiquitous hydrogen bonding . Materials involving thiophenes as XB acceptors have been overlooked, with only a handful of halogen-bonded complexes investigated by Watkins et al − and others. − It is important to further explore the use of XB-driven self-assembly of polythiophenes or other semiconducting polymers in organic electronics, prior to which one must understand the interactions that dictate the assembly of corresponding small-molecule-based building blocks, which is the journey we embarked on in this work.…”

Comparative Structural Study of Three Tetrahalophthalic Anhydrides: Recognition of X···O(anhydride) Halogen Bond and πh···O(anhydride) Interaction

“…Our experience in halogen bonding investigations [ 19 , 20 , 21 , 22 , 23 ] provides the clue that such X···X and X···O contacts may have a critical impact on a crystalline structure. We inspected XRD structures of TXPA and revealed several types of noncovalent interactions, including early undescribed contacts, which involve central anhydride oxygen atoms ( Figure 2 ).…”