On the Lack of Conjugation Stabilization in Polyynes (Polyacetylenes) Donald W. Rogers,*,† Nikita Matsunaga,† Frank J. McLafferty,† Andreas A. Zavitsas,† and Joel F. Liebman‡ Department of Chemistry and Biochemistry, The Brooklyn Campus, Long Island University, Brooklyn, New York 11201, and Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland 21250
[email protected] Received April 12, 2004
By analogy to conjugated polyenes, conjugative stabilization of polyynes with the -CtC-CtCgroup might be expected to be substantial. On the contrary, consistent with our recent report of a surprising lack of conjugative stabilization in butadiyne, we find by G3(MP2) calculations and by comparisons with available experimental data from these and other laboratories that the groundstate stabilization of conjugated polyynes is in fact quite small, amounting to
