Thermochemistry of arenetricarbonylchromium complexes containing toluene, anisole, N,N-dimethylaninine, acetophenone and methylbenzoate

Abstract Microcalorimetric measurements at elevated temperatures were made to determine the enthalpies of sublimation, of thermal decomosition, and of bromination of hexacarbonylchromium and of several (η-arene)tricarbonylchromium complexes. The standard enthalpies of formation (in kJ mol −1 ) of the crystalline and vapour states respectively of the [Cr(CO) 3 (η-ArX)] complexes were derived as X = CH 3 , −(473 ± 4), −(380 ± 5); X = OMe, −(593 ± 8), −(489 ± 8); X = NMe 2 , −(522 ± 8), −(404 ± 13); X = COMe, −(585 ± 13), −(478 ± 13); X = C(O)OMe, −(772 ± 8), −(659 ± 10). Values of the enthalpy of disruption reflect the weaker binding of η-arene ligands containing electron-accepting substituents.