Fig. 8. (a) ORTEP diagrams of the X-ray crystal structures of tethered Ru^II catalysts 15–18 with sulfonyl substituents on the diamine. Figure reproduced from ref. 23; F. Chen et al., Organometallics 2018, 37, 1555, published by The American Chemical Society. (b) TOFs for complexes 15–18 for NAD⁺ reduction in MeOH-d₄/D₂O (1 : 9 v/v) determined by UV-vis spectroscopy (final concentrations: Ru complex 28 μM, NAD⁺ 170 μM, NaHCO₂ 34 mM, molar ratio 1/6/1200)).²³ (c) Cell viability of A2780 cancer cells when incubated with complexes 15–18 (at equipotent 1/3 × IC₅₀ concentrations) and various sodium formate concentrations (0, 0.5, 1.0, and 2.0 mM) for 24 h. The figure is reproduced from ref. 23; F. Chen et al., Organometallics 2018, 37, 1555, published by The American Chemical Society.