Rupture and Repair of the Porphyrin Inner Core: Carbon-Nitrogen Bond Breaking and Formation in Ruthenium Complexes of an N,N'-Bridged Porphyrin

Article abstract of DOI:10.1021/ja00220a029

Treatment of the N,N'-vinyl-bridged porphyrin 1 with Ru3(CO)12 yields three products: the carbene complex TPPRu (3) (TPP is the dianion of tetraphenylporphyrin), and two Ru(II) dicarbonyl complexes 4 and 5 in which the N,N'-bridge remains intact, but the ruthenium has inserted into a pyrrole C-N bond.Complexes 4 and 5 differ in that 4 contains the C=C(p-ClC6H4)2 N,N'-bridge, while 5 contains a CHCH(p-ClC6H4)2 N,N'-bridge.Spectroscopic data (¹H NMr, UV/vis, infrared) for the three products are reported.Crystals of 4, Ru(CO)2 x 1/2 CH2Cl2, crystallize in the monoclinic space group p2₁/c with a = 12.633(7) Angstroem, b = 19293(10) Angstroem, c = 19.820(9) Angstroem, β = 95.59(3) grad, Z = 4 at 130 K.The structure was refined to R = 0.079 for 640 parameters and 4172 reflections.The ruthenium is six-coordinate with two cis carbon monoxide ligands, bonds to two normal pyrrole groups, and bonds to the C and N of the ring-opened pyrrole.The damaged porphyrin is no longer planar.Upon heating, both 4 and 5 undergo C-N bond formation to reform the porphyrin ring.