DFT Study of Thermal 1,3-Dipolar Cycloaddition Reactions between Alkynyl Metal(0) Fischer Carbene Complexes and 3H-1,2-Dithiole-3- thione Derivatives

DIEGO M. ANDRADA; ALEJANDRO M. GRANADOS; MIQUEL SOLÁ; ISRAEL FERNÁNDEZ

ORGANOMETALLICS

AMER CHEMICAL SOC

Año: 2011 vol. 30 p. 466 - 476

0276-7333

The thermal 1,3-dipolar cycloaddition reaction between alkynyl metal(0) Fischer carbenes and5-methyl-3H-1,2-dithiole-3-thione to yield 1,3-dithiafulvene has been studied computationallywithin the Density Functional Theory framework. The transformations involving Fischer carbenecomplexes and their isolobal analogues (organic esters and corresponding Lewis acid complexes)were compared in terms of regioselectivity, barrier and reaction energies, synchronicity, andaromaticity of the corresponding transition states. These reactions are found to be concerted andcompletely regioselective toward the formation of theZ-1,3-dithiafulvene isomer, which is kineticallyfavored. DFT calculations are in good agreement with the experimental outcome of the process,which can be explained by means of the corresponding frontier molecular orbitals of reactants andtheir electrostatic potentials.