In this paper the effect of the cyano group (CN) on the heats of formation of small, gas-phase organic cations was investigated. The C N substituent has a predictable and significant influence on cationic heats of formation which does not vary greatly for saturated and unsaturated ions. It was found to increase the AfHo298 of radical cations by 42-44 kcal mol-' compared with their H-substituted analogues. The effect of C N substitution on neutral molecules is ca. 32 kcal mol-', and so the ionization energy of a CN-substituted molecule is larger than for its unsubstituted analogue by approximately 10-12 kcal mol-'. This is supported by calculations which show that the C N group does not conjugate significantly with the positive charge center, i.e. it behaves as an inductive electron-withdrawing substituent. The ionization energies of the three neutral molecules, cyanoketene, benzoyl cyanide, benzoylacetonitrile (9.93 f 0.26, 9.89 f 0.09, and 9.54 f 0.09 eV, respectively), and their cationic heats of formation (253 f 3,256 f 2,237 f 2 kcal mol-', respectively) were determined for the first time, along with the heat of formation of neutral cyanoketene, 24 f 5 kcal mol-', the cyanoacetyl cation, 198 i 3 kcal mol-', and the cyanoacetyl radical, 32 f 1 kcal mol-'.

A new catalytic strategy for the one-pot synthesis of N-sulfonylamidines is described. The cationic copper(I) complexes were found to be highly active and efficient under mild conditions in air and in the absence of solvent. A copper acetylide is proposed as key intermediate in this transformation.

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