Beschreibung:
<jats:title>Abstract</jats:title><jats:p>(η<jats:sup>6</jats:sup>‐Arene)tricarbonylchromium <jats:bold>2</jats:bold> was synthesised by [3+2+1] benzannulation of the Fischer carbene complex <jats:bold>1</jats:bold> and converted to the thermodynamically more favorable regioisomer <jats:bold>3</jats:bold> by haptotropic metal migration. Photo‐induced ligand‐exchange reactions in both regioisomers with triphenylphosphine, triphenylphosphite, trimethylphosphine, and trimethylphosphite afforded dicarbonyl(phosphine or phosphite)arene complexes <jats:bold>4</jats:bold>–<jats:bold>11</jats:bold>. The regioisomers were separated by high‐performance liquid chromatography (HPLC), and kinetic analyses of the thermo‐induced haptotropic metal shift were performed with regioisomers <jats:bold>4</jats:bold>, <jats:bold>6</jats:bold>, <jats:bold>8</jats:bold>, and <jats:bold>10</jats:bold>. The kinetic parameters were compared with those obtained for the parent tricarbonyl complex <jats:bold>2</jats:bold> and were discussed in terms of the steric and electronic properties of the phosphorus ligands by applying a quantitative analysis of ligand effects (QALE). The molecular structures of regioisomeric PPh<jats:sub>3</jats:sub> and P(OPh)<jats:sub>3</jats:sub> complexes <jats:bold>4</jats:bold>/<jats:bold>5</jats:bold> and <jats:bold>6</jats:bold>/<jats:bold>7</jats:bold> as well as of P(OMe)<jats:sub>3</jats:sub> complex <jats:bold>10</jats:bold> have been established by single‐crystal X‐ray analysis.</jats:p>