Di-μ-acetato-κ⁴O:O′-μ-oxido-κ²O:O′-bis[cis-(2,2′-bipyridine-κ²N,N′)-trans-(pyridine-κN)ruthenium(III)] bis(hexafluoridophosphate)

Abstract

The hemerythrin-type dinuclear title complex, [Ru2(CH3COO)2O(C10H8N2)2(C5H5N)2](PF6)2, consists of two RuIII ions with a six-coordinate octa­hedral geometry, bridged by an oxide and two acetate ligands, with a bidentate 2,2′-bipyridine ligand and a pyridine ligand bonding at terminal positions. The Ru—Ru distance and Ru—O—Ru angle are 3.2838 (3) Å and 121.79 (7)°, respectively, and the average Ru—N(pyridine) bond length is 2.164 (8) Å. Several C—H⋯F, C—H⋯O and C—H⋯N inter­actions generate a three-dimensional network in the crystal structure. π–π stacking inter­actions [centroid–centroid distance = 3.6389 (3) Å] between inversion-related 2,2′-bipyridine rings are also observed.

The First Bis(μ‐acetato)(μ‐oxido)diruthenium(III) Complexes Containing Sulfur Donor Ligands

“…For example, the absorption of [Ru III 2 (μ-O)(μ-CH 3 CO 2 ) 2 (bpy) 2 (4-aminopyridine) 2 ] 2 + is located at a longer wavelength compared with that of 1, despite 4-aminopyridine being a stronger Lewis base than py. [33] In the present study, the wavelength of the absorption maximum of 5 was found to be similar to (not shorter than) that of 1, although the pK a of thiazole is lower than that of py. These results further corroborate the enhanced contribution of the covalency to the coordination bond.…”

“…The latter terminal ligands are sulfur-bonded dhtp in 4 and nitrogenbonded thiazoles in 5. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 The Ru⋅⋅⋅Ru distances (3.2733(6) Å in 4 and 3.2766(7) Å in 5) and the Ru-O-Ru angles (122.19(18)°in 4 and 121.65 (19) in 5) are very similar to the corresponding values in 1, i. e. 3.2838(3) Å and 121.79(7)°, [33] respectively, where the terminal L ligands at the trans-to-oxido positions are nitrogen-bonded py. Moreover, Ru-(μ-O) bond lengths in 4 (av.…”

“…Since the pK a of the protonated ligand HL is a useful index of the σ-donor ability of the L ligand, a correlation between the Ru-L bond lengths and the pK a for nitrogen donor ligands, e. g. py and imidazole, can be identified. [33] Thus, the Ru-N bond lengths at the trans-to-oxido sites in [Ru III 2 (μ-O)(μ-CH 3 CO 2 ) 2 (bpy) 2 (L) 2 ] 2 + was reported to increase in the sequence 2.125 Å for L = 1-methylimidazole (pK a = 7.06) [19] < 2.152 Å for L = 3-aminopyridine (pK a = 6.03) [32] < 2.164 Å for L = py (pK a = 5.17). [33] In these complexes, the stronger σ-donor forms the stronger Ru-L coordination bond.…”

“…[33] Thus, the Ru-N bond lengths at the trans-to-oxido sites in [Ru III 2 (μ-O)(μ-CH 3 CO 2 ) 2 (bpy) 2 (L) 2 ] 2 + was reported to increase in the sequence 2.125 Å for L = 1-methylimidazole (pK a = 7.06) [19] < 2.152 Å for L = 3-aminopyridine (pK a = 6.03) [32] < 2.164 Å for L = py (pK a = 5.17). [33] In these complexes, the stronger σ-donor forms the stronger Ru-L coordination bond. However, the Ru-N trans length of 5 (2.157 Å) is virtually the same as that of 1, despite thiazole being a far weaker Lewis base (pK a = 2.53) than py.…”

“…In the study of the functions and biological mechanisms of diiron enzymes, second‐ and third‐row transition metal complexes have been resorted to for over several decades as substitutes of the more labile iron complexes with the general formula [Fe III 2 ( μ ‐O)( μ ‐RCO 2 ) 2 L n ] m + (L: terminal ligand). Particularly, a number of diruthenium complexes with various ligands, which mimic their iron congeners, have been extensively synthesized and studied from the viewpoints of structure, electrochemistry, spectroscopy, catalysis and kinetic behavior …”