Metall-π-komplexe von benzolderivaten : XVI. Über die konformative beweglichkeit von bis(1-methyl-4-t-butyl-η-benzol)chrom

Abstract In what appears to be, to our knowledge, the first investigation of hindered rotation about the metalligand bond in a bis(arene)-transition metal complex in solution, we have studied by 1 H and 13 C NMR spectroscopy the conformational interconversion of two rotamers of bis(1-methyl-4-t-butyl-η-benzene)-chromium(0). As constants for the Arrhenius equation we obtained the values E a = 35.6 ± 1.6 kJ mol −1 and log A = 11.9 ± 0.4. Alternatively, the parameters of the Eyring equation were determined as Δ G ≠ = 40.4 ± 4 kJ mol −1 Δ H ≠ = 34.0 ± 1.6 kJ mol −1 and Δ S ≠ = −22 ± 8 JK −1 mol − .