Tricyanomethyl

First examine the geometry of methyl radical. Is it planar or puckered Examine the geometries of 2-methy 1-2-propyl radical, trifluoromethyl radical, trichloromethyl radical and tricyanomethyl radical. Classify each of the substituents (methyl, fluoro, chloro and cyano) as a n-electron donor or as a Tt-electron acceptor (relative to hydrogen). Does replacement of the hydrogens by 7t-donor groups make the radical center more or less puckered Does replacement by Jt-acceptor groups make the radical center more or less puckered Justify your observations. 

Onto which atoms (carbon, nitrogen or both) is the unpaired electron in tricyanomethyl radical delocalized Rationalize your result by drawing resonance contributors. 

The above book [1] deals, in 26 chapters in 5 sections, with theoretical and practical aspects of the use and safe handling of powerful oxidants and their complementary reactive fuels. Materials include nitrogen pentaoxide, perfluoroam-monium ion and salts, nitronium tetrafluoroborate, hydrazinium mono- and diperchlorates, nitronium perchlorate, tricyanomethyl compounds, difluoramine and its alkyl derivatives, oxygen difluoride, chlorine trifluoride, dinitrogen tetraoxide, bromine trifluoride nitrogen fluorides, and liquid ozone-fluorine system. 

Synthesis and Thermochemistry of Tricyanomethyl and Other Polycyano Compounds... 

A series of tricyanomethyl compounds were prepared in refluxing acetonitrile hy alkylating potassium tricyanometha-nide with alkyl iodides, allyl, propargyl, and benzyl bromides. Yields of 20-57% were obtained for mono- and difunctional halides with a reflux time of 72 hours. The heats of combustion of these tricyanomethyl compounds as well as of two polycyano compounds were measured using a Dickenson-type calorimeter, and heats of formation were calculated with a precision of approximately 1.0%. From Pitzers values for C—C and C—H bond energies, that of the tricyanomethyl moiety is calculated to be about 810 kcal./mole, and the tricyanomethyl group is less stable than expected from comparison with AH°f of propylcyanide. 

The tricyanomethyl compounds are a stable class of organic compounds whose solid products can be purified by sublimation. Their exceptional thermal stability is evidenced by the fact that 1,1,1,6,6,6-hexa-cyanobutyne-3 was sublimed at 170° C./0.05 mm. The infrared spectra of these compounds show a weak absorption for cyano at 4.4 /a. The properties of these compounds are summarized in Table I. 

In addition to the above tricyanomethyl compounds, 1,4-dicyano-butyne-2 (8) and 1,1,2,2-tetracyanocyclopropane (22) were prepared for the thermochemical studies. 

It is also possible to calculate the bond energy of the tricyanomethyl moiety in each of the molecules. To do this we calculate standard heats of formation at 0° K. from the values given in Table III for 298° C. In the absence of reliable data we note the following reported (13) specific heats, Cp ... 

These are also original results which could explain the low decay rate constant of the tricyanomethyl radical. 

CONH2 and COOMe, is discussed on p. 214. Isocyanatomethyl, Fe—CH2NCO and alkoxycarbonyl, Fe—COOR derivatives have also been prepared [55 ]. The tricyanomethyl complex, r-C5H5Fe(CO)2C(CN)3 has been prepared from 7r-C5H5Fe(CO)2Cl using Ag+[C(CN)3] [50]. 

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