DIRUTHENIUM(III) COMPOUNDS, RU2O(O2CAR)2(MECN)4(PPH3)2(CLO4)2.H2O AND RU2O(O2CAR)4(PPH3)2, WITH AN (RU2(MU-O)(MU-O2CAR)2(2+)) CORE AS MODEL SYSTEMS FOR THE DIIRON CENTERS IN HEMERYTHRIN

Diruthenium(III) compounds, Ru2O(O2CAr)2(MeCN)4(PPh3)2(ClO4)2•H2O (1) and Ru2O(O2CAr)4(PPh3)2 (2) (Ar = Ph, C6H4-p-OMe), were prepared by reacting Ru2Cl(O2CAr)4 and PPh3 in MeCN and characterized by analytical and spectral data. The molecular structures of 1 with Ar = Ph and of 2 with Ar = C6H4-p-OMe were determined by X-ray crystallography. Crystal data for Ru2O(O2CPh)2(MeCN)4(PPh3)2(ClO4)2•H2O (1a): monoclinic, C2/c, a = 27.722 (3) Å, b = 10.793 (2) Å, c = 23.445 (2) Å, β = 124.18 (1)°, V = 5803 Å3, and Z = 4. Crystal data for Ru2O(O2CC6H4-p-OMe)4(PPh3)2 (2b): orthorhombic, Pnna, a = 22.767 (5) Å, b = 22.084 (7) Å, c = 12.904 (3) Å, V= 6488 Å3; and Z = 4. Both 1 and 2 have an {Ru2O(O2CAr)22+} core that is analogous to the diiron core present in the oxidized form of the nonheme respiratory protein hemerythrin. The Ru-Ru distances of 3.237 (1) and 3.199 (1) Å observed in 1 and 2, respectively, are similar to the M-M distances known in other model systems. The essentially diamagnetic nature of 1 and 2 is due to the presence of two strongly interacting t2g5 RuIII centers. The intense colors of 1 (blue) and 2 (purple) are due to the charge-transfer transition involving an (Ru2(μ-O)4+] moiety. The presence of labile MeCN and carboxylato ancillary ligands in 1 and 2, respectively, makes these systems reactive toward amine and heterocyclic bases. © 1990, American Chemical Society. All rights reserved.