Isomer effect on the structure and chemical reactivity of diruthenium complexes. Synthesis and characterization of the (4,0), (3,1), and (2,2) trans isomers of Ru-2(F(5)ap)(4)Cl and Ru-2(F(5)ap)(4)(C equivalent to CC6H5)(2) where F(5)ap is the 2-(2,3,4,5,6-pentafluoroanilino)pyridinate anion

The syntheses and characterization of the (4,0), (3,1), and (2,2) trans isomers of Ru-2(F(5)ap)(4)Cl and Ru-2(F(5)ap)(4)-(C=CC6H5)(2) are reported where F(5)ap is the 2-(2,3,4,5,6-pentafluoroanilino)pyridinate anion. The (4,0), (3,1), and (2,2) trans isomers of Ru-2(F(5)ap)(4)Cl were separated on a silica gel column following the reaction between Ru-2(CH3COO)(4)Cl and molten HF(5)ap under argon. The (4,0), (3,1), and (2,2) trans isomers of Ru-2(F(5)ap)(4)-(C=CC6H5)(2) were obtained by reaction of their respective isomer of Ru-2(F(5)ap)(4)Cl with LiC=CC6H5 in THF at room temperature. The three isomers of Ru-2(F(5)ap)(4)Cl and Ru-2(F(5)ap)(4)(C=CC6H5)(2) were characterized by H-1 and F-19 NMR, ESR, and IR spectroscopy, mass spectrometry and electrochemistry. Each (RuRuIII)-Ru-II isomer of RU2(F-5 ap)(4)Cl is paramagnetic and undergoes two oxidations and one reduction in CH2Cl2, 0.1 M TBAP while each Ru-2(III) isomer of Ru-2(F(5)ap)(4)(C=CC6H5)(2) is diamagnetic and undergoes one oxidation and two reductions under the same solution conditions. All of the redox processes are reversible and involve metal-centered one-electron transfers. The singly reduced products of the (4,0), (3,1), and (2,2) trans isomers of Ru-2(F(5)ap)(4)(C=CC6H5)(2) were electrogenerated and display ESR signals consistent with the presence of a single unpaired electron. Molecular structures of the three isomers of Ru-2(F(5)ap)(4)(C=CC6H5)(2) were also determined. The (4,0) isomer crystallizes in the monoclinic space group P2(1)/c with a = 23.436(6) Angstrom, b = 20.640(6) Angstrom, c = 23.504(6) Angstrom, beta = 105.82(2)degrees, and Z = 8, while the (3,1) isomer crystallizes in the monoclinic space group P2(1)/n with a 15.621(3) Angstrom, b = 16.427(3) Angstrom, c = 21.166(5) Angstrom, beta = 93.91(2)degrees, and Z = 4. The (2,2) trans isomer crystallizes in the triclinic space group P(1<Over bar>) with a = 12.819(5) Angstrom, b = 13.390(4) Angstrom, c = 17.827(5) Angstrom, alpha = 85.04(2)degrees, beta = 72.66(2)degrees, gamma = 68.47(2)degrees, and Z = 2. The average Ru-Ru bond distances in the (4,0), (3,1), and (2,2) trans isomers of Ru-2(F(5)ap)4-(C=CC6H5)(2) are 2.450(1), 2.475(1), and 2.473(1) Angstrom, respectively.