Single-crystal EPR study of the thermally accessible 3Bu state of trans-(CNSSS)22+
✍ Scribed by Attila Berces; Gary D. Enright; Graham E. McLaurin; John R. Morton; Keith F. Preston; Jack Passmore; Dale J. Wood
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 105 KB
- Volume
- 37
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
CNSSS) 2 2C (Sb 2 F 11 2 was successfully doped into single crystals of the isostructural diamagnetic material (CNSNS) 2 2C (Sb 2 F 11 2 and the EPR spectrum of the thermally accessible electronically excited 3 B u state of the dopant cation was measured as a function of angle in three arbitrary, but crystallographically established, planes of the host crystal. A computer program was used to determine the principal values of g and D, the spin-spin interaction tensor, for the impurity triplet, to locate them within the host lattice and, by inference, to place them on the C 2h structure of the trans dication guest. Within experimental error, g and D are coaxial, not a requirement of the dication symmetry. The minimum principal value of g (2.0022) and the intermediate value of D (218 MHz) both lie within less than 2 °of the perpendicular to the molecular plane, as expected for a radical and as required by symmetry. Within the dication plane, the maximum principal values of g (2.0271) and of D ( 395 MHz) lie 15 °from the C-C bond. Classical calculations of the dipolar coupling support these observations and their interpretation in terms of a biradical character of the triplet state in which the unpaired electrons are effectively isolated, one in each ring.