Solid‐State Confinement Effects in Selective <i>exo</i> ‐H/D Exchange in the Rhodium σ‐Norbornane Complex [(Cy ₂ PCH ₂ CH ₂ PCy ₂ )Rh(η ² :η ² ‐C ₇ H ₁₂ )][BAr ^F ₄ ]

Density functional theory calculations modelling selective exo-H/D exchange observed in the Rh σ-alkane complex [(Cy2PCH2CH2PCy2)Rh(η2:η2-endo-NBA)][BArF4], [1-NBA][BArF4], are reported, where ArF=3,5-C6H3(CF3)2 and NBA=norbornane, C7H12. Two models were considered 1) an isolated molecular cation, [1-NBA]+ 2) a full model which [1-NBA][BArF4] is treated solid state through periodic DFT. After initial endo-exo rearrangement, both predict H/D to proceed D2 addition oxidative cleavage followed by rate-limiting C−H activation of norbornane σ-CAM step form [1-Rh(D)(η2-HD)(norbornyl)]+ intermediate. HD rotation C−D bond formation, reductive coupling loss then complete process. facilitated supporting agostic interaction consistently more accessible kinetically than potentially competing endo-H/D (isolated cation: ΔG≠exo=+15.9 kcal/mol, ΔG≠endo=+18.4 kcal/mol; state: ΔG≠exo=+22.1 ΔG≠endo=+25.1 kcal/mol). The solid-state environment has significant impact on computed energetics, with barriers increasing ca. 7 while only correctly predicts endo-bound NBA be resting system. These outcomes reflect confinement effects within pocket occupied cation defined pseudo-octahedral array neighbouring [BArF4]− anions. asymmetry also requires second pathway account for reaction at all four exo-C−H bonds. entail slightly higher (ΔG≠exo= +24.8 ΔG≠endo=+27.5 kcal/mol) but retain distinct preference exo- over exchange.