Reactions of rhodium porphyrins with lactones, silanes, and stannanes

Article abstract of DOI:10.1021/om00001a049

(2,3,7,8,12,13,17,18-Octaethylporphyrinato)rhodium(I) (Rh^IOEP) cleaved the alkyl-oxygen bond of four-membered-ring and five-membered-ring lactones (β-propiolactone (1), β-butyrolactone (2), and γ-butyrolactone (3)) at room temperature to regioselectively yield (ω-carboxyalkyl)Rh^IIIOEP. [{Rh^IIOEP}₂] reacted with R¹₂R²MH (8, M = Si, R¹ = R² = Et; 9, M = Si, R¹ = R² = Ph; 10, M = Si, R¹ = Me, R² = Ph; 11, M = Si, R¹ = Me, R² = OEt; 16, M = Sn, R¹ = R² = Bu; 17, M = Sn, R¹ = R² = Ph) to yield Rh^III(MR¹₂R²)OEP. These alkyl-, silyl-, and stannylrhodium complexes of OEP were characterized by ¹H, ¹³C, ²⁹Si, and ¹¹⁹Sn NMR, IR, UV-vis, and mass spectroscopy. (triethylsilyl)Rh^IIIOEP crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 17.14(8) A?, b = 14.94(5) A?, c = 31.22(5) A?, and β = 103.5(2)°; the density is 1.28 g/cm³ for Z = 8. The porphyrin plane is almost planar, and the rhodium metal resides on the plane. The Rh-Si distance is 2.32(1) A?, and all the eight ethyl groups on the pyrroles are directed toward the triethylsilyl group. The present method has proved to be a facile way to prepare bimetallic rhodium complexes of porphyrin.