ATTRACTIVE INTERACTIONS BETWEEN AN ALKYNE GROUP AND 2 CARBONYL OXYGEN-ATOMS - THE CRYSTAL-STRUCTURE AND MOLECULAR-STRUCTURE OF 2,2'-ETHYNYLENEDIBENZOIC ACID AT 150-K

The X-ray crystal structure of 8 shows two attractive intramolecular i nteractions between sp carbon atoms and adjacent carbonyl oxygen atoms , leading to a twisting of the triple bond equivalent to an orthogonal combination of cis and trans bends; the two carboxylic acid groups li e to the same side of the triple bond to avoid unfavourable contacts b etween carbonyl oxygen atoms and incipient carbanionic centres.