Details

Autor(en) / Beteiligte

• Janicki, Slawomir Z
• Petillo, Peter A

Titel

Triplet Ground State of 2,5-Dimethylene Five-Member Heterocycles

Ist Teil von

• The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 1999-04, Vol.103 (15), p.2873-2877

Ort / Verlag

American Chemical Society

Erscheinungsjahr

1999

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• 2,5-Dimethylene five-member heterocycles have been thought to possess exclusively singlet ground states. On the basis of the analysis of charge redistribution upon switching the state multiplicity of π-CASSCF optimized geometries, we calculate that the 2,5-dimethyleneborole dianion should exist in a triplet ground state. Additionally, the 2,5-dimethyleneborole dianion and the analogous 2,5-dimethylenealanacyclopentadiene dianion, 2,5-dimethyleneberyllacyclopentadiene trianion, and 2,5-dimethylenemagnesacyclopentadiene trianion have triplet ground states at the MCQPDT2 level in the CASSCF geometry. Furthermore, we find the upper limit of the S−T gap, |ΔE S - T| to be 50 kcal/mol, which correlates with the S−T gap calculated for the parent hexatriene hydrocarbon. The ΔE S - T trend approximately follows the group electronegativity scale of Boyd and Boyd derived from the bond critical point model for the heteroatom and protons attached to it. The 2,5-dimethyleneborole dianion and its analogues are members of a new class of ferromagnetic coupling units (FCs) for use in the construction of molecular organic ferromagnets.