The Microwave Spectra and Molecular Structures of Cyclopentene and Cyclobutene Ozonides and 1,2,4-Trithiolane.

The rotational spectra of fourteen isotopic species of cyclopentene ozonide (6,7,8-trioxabicyclo{3.2.1}octane, CpOz) were assigned. The structure of CpOz was analyzed by both the least-squares (r(,o)) and Kraitchman's substitution (r(,s)) methods. The ground state structure of CpOz has C(,s) symmetry and the endo conformation. Some of the significant r(,o) structural parameters are: r(O(,p)-O(,p)) = 1.475(1) (ANGSTROM); r(C(,b)-O(,p)) = 1.430(2) (ANGSTROM); r(C(,b)-O(,e)) = 1.414(2) (ANGSTROM); r(C(,b)-C(,(alpha))) = 1.528(2) (ANGSTROM); r(C(,(alpha))-C(,f)) = 1.540(2) (ANGSTROM); (ANGLE)C(,b)-O(,p)-O(,p) = 104.3(1)(DEGREES); (ANGLE)C(,b)-O(,e)-C(,b) = 101.0(1)(DEGREES); (ANGLE)O(,p)-C(,b)-O(,e) = 104.2(1)(DEGREES); (ANGLE)O(,p)-C(,b)-C(,(alpha)) = 111.6(1)(DEGREES); (ANGLE)O(,e)-C(,b)-C(,(alpha)) = 110.4(1)(DEGREES); (ANGLE)C(,b)-C(,(alpha))-C(,f) = 109.4(1)(DEGREES); (ANGLE)C(,(alpha))-C(,f)-C(,(alpha)) = 110.3(2)(DEGREES). The uncertainties shown represent one st and ard deviation in the least squares fit of the observed inertial parameters. The structure of CpOz is discussed in relation to ab initio molecular orbital calculations of the C(,s) conformer of ethylene ozonide. The dipole moment has been determined as 2.478(9) Debye. Cyclobutene ozonide (2,3,7-trioxabicyclo{2.2.1}heptane, CbOz) has been isolated from the ozonolysis of cyclobutene in saturated hydrocarbon solvents. The rotational spectra of the normal isotopic species and one vibrational satellite were assigned. The dipole moment of CbOz has been determined as 2.857(2) Debye. The data is consistent with the molecule belonging to the C(,s) symmetry point group. The rotational spectra of eight isotopic species of 1,2,4-trithiolane (the sulfur analog of ethylene ozonide, SOz) were assigned. The structure of SOz was determined by both the least-squares (r(,o)) and Kraitchman's substitution (r(,s)) methods. The molecule has a disulfide twist half-chair conformation belonging to the C(,2) symmetry point group. The structural parameters determined for the ring atoms are as follows: r(S-S) = 2.044(2)(ANGSTROM); r(C-S(,s)) = 1.829(2)(ANGSTROM); r(C-S(,d)) = 1.808(2)(ANGSTROM); (ANGLE)C-S-S = 93.8(1)(DEGREES); (ANGLE)C-S-C = 99.4(1)(DEGREES); (ANGLE)S-C-S = 110.0(1)(DEGREES); (ANGLE)C-S-S-C = 52.8(3)(DEGREES); (ANGLE)S-S-C-S = -46.4(4)(DEGREES); (ANGLE)C-S-C-S = 20.2(1.0)(DEGREES). The conformation of SOz is explained by the lone pair interactions of the disulfide atoms with the C-S(,s) (sigma)* orbital. The dipole moment has been determined as 0.465(2) Debye.Ph.D.Physical chemistryUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/159139/1/8304446.pd