(where 𝜆 is the spin-orbit coupling constant and Δ𝐸 ' ( ⟵*',,' is the energy gap between the dz 2 and dxz/ dyz orbitals) a lower g⊥ value is expected for 6 than for Rh(II)-3. Theoretical calculations located an energy minimum for an η 1 σ-adduct that features a 146° Rh-H-Si angle (Figure ). In theoretical calculations, a Gibbs energy of ΔGcalc = -3.1 kcal•mol -1 was obtained for σ-adduct 6, along with predicted EPR parameters that are in good agreement with experimental observation (Figure , Table ). The Si-H bond is only slightly elongated in 6 (1.56 Å) compared to the Si-H bond in the free silane (1.51 Å), and back-donation from the Rh(II) SOMO to the Si-H σ* orbital makes only a minimal contribution to the Rh-silane interaction in 6 (Table ). Theoretical calculations also predicted a maximum hyperfine splitting of about 48 MHz due to the H atom that bridges the Rh and Si centers. Unfortunately, the spectral features expected due to the coupling to 1 H were not fully resolved in the spectrum and generated only a broadening of the EPR signal around g = 1.980.