The crystal and molecular structure of tropolone

Abstract

Tropolone, C7H602, crystallizes in space group P21/e, with a= 7.135, b---12.178, c= 7.122 A, fl= 99.63 ° and Z= 4. The crystal structure was solved by the symbolic addition procedure and refined by the leastsquares method to give the final R value of 0.054 for the 853 observed reflexions. The molecule is essentially planar and exhibits a slight degree of bond alternation in the seven-membered ring. The hydroxyl group makes a bifurcated hydrogen bond with carbonyl oxygen atoms, of which one branch is intramolecular and the other intermolecular. The latter intermolecular branches form a hydrogenbonded dimer. These characteristic hydrogen bonds seem to play a role in increasing the contribution from the dipolar ionic forms to the ground state of the tropolone molecule.

The crystal structures of tropolone and 4-isopropyltropolone: a comparison

“…The carbonoxygen bonds are also involved in the electron delocalization as indicated by the lengths, C(1)-O(1)=1-261 and C(2)-O(2)= 1"349 A. A revised report on the tropolone structure, based on re-measured intensities, has now appeared (Shimanouchi & Sasada, 1973). This indicates that there is in fact bond-length alternation in the ring, in agreement with the situation in IPT.…”

“…Shimanouchi & Sasada (1973) noted that the ring in tropolone adopts a boat conformation similar to, but shallower than, that observed for a number of tropones. In the tropones, the 'boat' is described in terms of the planes defined by the three groups of atoms C(1,2,7), C(2,3,6,7) and C (3,4,5,6), and these same groups of atoms were used to describe the boat conformation of the tropolone ring, the r.m.s, atomic deviations being 0, 0-009 and 0.007 /~, respectively.…”

Crystal structure of 3,5,7-tris(morpholinomethyl)tropolone·0.67 hydrate, C22H33N3O5·0.67H2O

“…The title compound consists of a tropolone core with three methyl morpholine moieties bound to it at C3, C5 and C7 of the backbone, with additional water (0.67 occupancy) completing the asymmetric unit, as shown in the gure. Earlier in the 1970′s, Shimanouchi et al reported the molecular structure of tropolone [10,11]. When comparing this structure to that of tropolone, some slight deviations were observed within the tropolone core.…”

X-ray crystallographic studies on cycloheptadithiophene compounds and similar systems. IV. The crystal structure of 9H-cyclohepta[2,1-b:5,6-c']dithiophen-9-one

“…Bond lengths and angles involving hydrogen atoms 1968; Ibata, Hata, Shimanouchi & Sasada, 1972;Shimanouchi & Sasada, 1973) and by an SCM MO method (Dewar & Trinajsti6, 1970a, b) has a sevenmembered ring with a marked boat form with the planes of the two benzene rings inclined to each other at an angle of about 39 ° . It appears that when benzene rings are fused to the tropone ring there is a large dihedral angle while five-membered rings give planar molecules.…”