THERMOCHEMISTRY OF CYCLOBUTADIENE AND TETRAHEDRANE - A HIGH-LEVEL COMPUTATIONAL STUDY

The thermochemical properties of cyclobutadiene and tetrahedrane have been calculated using high-level MO calculations at the G2 level of th eory. Enthalpies of formation of cyclobutadiene and tetrahedrane at 29 8 K are calculated to be 426 +/- 4 and 535 +/- 4 kJ mol(-1), respectiv ely. Antiaromatic destabilization of cyclobutadiene and the strain ene rgy of tetrahedrane have been estimated to be 170 +/- 7 and 571 +/- 4 kJ mol(-1) (at 298 K), respectively. The value of the antiaromatic des tabilization of cyclobutadiene (42.5 kJ mol(-1)) per pi electron is la rger than the aromatic stabilization of benzene per pi electron (15.4 kJ mol(-1)).