Hydrogen bonding in 2-hydroxybenzoic, 2-hydroxythiobenzoic,and 2-hydroxydithiobenzoic acid. A structural and spectroscopic study

Summary X-ray structural data are reported for 2-hydroxythiobenzoic acid (T=200 K;P2₁/a;a=14.903(5) Å,b=5.203(3) Å,c=9.114(6) Å, =92.40(4)°;Z=4;R=0.049) and 2-hydroxydithiobenzoic acid (T=297 K;P2₁/a;a=14.416(3) Å,b=13.447(3) Å,c=3.947(1) Å, =90.96(2)°;Z=4;R=0.047). In 2-hydroxythiobenzoic acid, each two molecules form cyclic dimersvia S-H...O=C hydrogen bonds, analogous to the association pattern of 2-hydroxybenzoic acid. In 2-hydroxydithiobenzoic acid, the molecules are linked to chains by S-H...O(H)-C hydrogen bonds. Solid state IR, and solution IR and NMR spectroscopic data of 2-hydroxybenzoic acid, 2-hydroxythiobenzoic acid, and 2-hydroxydithiobenzoic acid are summarized. The main characteristics of the intramolecularly associated phenolic O-H groups of the three title compounds are for the solids, for solutions (CCl₄), and _OH=10.21, 10.53, 12.20 ppm for solutions (CCl₄:CDCl₃=5:1).Dedicated to Prof.O. Olaj on the occasion of his 60^th birthday