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|Title:||The Electronic Structure of The Trifluoride Ion and a New Synthesis and Reactions of 3-Chloro-1,2,3-Tris (Trifluoromethyl) Cyclopropene (Metallatetrahedrane, Molybdenum, Hypervalent)|
|Author(s):||Cahill, Paul Augustine|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The electronic structure of the hypervalent trifluoride ion has been calculated at the ACCD (approximate coupled clusters with doubles substitution) level. The ion was calculated to be symmetric (point group D(,(INFIN)h)) and stable with respect to F('-) and F(,2) by 11 kcal/mol.
Ab initio SCF calculations on the hypothetical complexes ((eta)('3)-C(,3)R(,3))(,2)E (R = H, E = Si, S) indicate that closed shell electronic configurations may exist for either 8, 10 or 12 electron species. The synthesis of such species (for R = CF(,3) and E = nonmetal) has so far been unsuccessful. The effects of placing electron withdrawing substituents on ((eta)('3)-C(,3)R(,3))-transition metal complexes has also been evaluated. The synthesis and X-ray structure determination of ((eta)('5)-C(,5)H(,4)CH(,3)) (eta)('3)-C(,3)(CF(,3))(,3) Mo(CO)(,2) (1), the first (eta)('3)-C(,3)R(,3) complex that incorporates an electron withdrawing C(,3)(CF(,3))(,3) ring, is best described not as a (eta)('3)-cyclopropenium complex but as a metallatetrahedrane.
The synthesis of several new trifluormethylated cyclopropanes including tris(trifluoromethyl)cyclopropane is detailed. These cyclopropanes were prepared during the development of new syntheses of 3-chloro- and 3-iodo- 1,2,3-tris(trifluoromethyl)cyclopropene (2a,b) from CF(,3)CdX (X = Br, Cl) and 3,3-dichloro-1,2-bis(trifluoromethyl)cyclopropene. Dimethylsulfoxide / NaI oxidation of 2a gives the sodium salt of 1,1,1,5,5,5-hexafluoro-3-trifluoromethyl-2,4-pentanedione. The activation parameters for iodide positional exchange on 2b via formal SN2' attack of iodide ion are: (DELTA)H* = 9.3 (1.0) kcal/mol, (DELTA)S* = -10.9 (4.1) eu, (DELTA)G*(,298) = 12.6 (1.0) kcal/mol in acetonitrile.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986.
|Date Available in IDEALS:||2014-12-15|