Substituent-Directed Structural and Physicochemical Controls of Diruthenium Catecholate Complexes with Ligand-Unsupported Ru−Ru Bonds

Abstract

A family of diruthenium complexes with ligand-unsupported Ru-Ru bonds has been systematically synthesized, and their crystal structures and physical properties have been examined. A simple, useful reaction between Ru2(OAc)4Cl (OAc- = acetate) and catechol derivatives in the presence of bases afforded a variety of diruthenium complexes, generally formulated as [Na(n){Ru2(R4Cat)4}] (n = 2 or 3; R4 = -F4, -Cl4, -Br4, -H4, -3,5-di-t-Bu, and -3,6-di-t-Bu; Cat(2-) = catecholate). The most characteristic feature of the complexes is the formation of short ligand-unsupported Ru-Ru bonds (2.140-2.273 A). These comprehensive studies were carried out to evaluate the effects of the oxidation states and the substituents governing the molecular structures and physicochemical properties. The Ru-Ru bond distances, rotational conformations, and bending structures of the complexes were successfully varied. The results presented in this manuscript clearly demonstrate that the complexes with ligand-unsupported Ru-Ru bonds can sensitively respond to redox reactions and ligand substituents on the basis of the greater degree of freedom in their molecular structures.

Hydrodeoxygenation of Phenol and Derivatives over an Ionic Liquid‐Like Copolymer Stabilized Nanocatalyst in Aqueous Media

“…In sharp contrast, only a moderate conversion 60 % of catechol was obtained to give cyclohexanol as a predominant product under the same reaction conditions, suggesting a catalyst deactivation by means of formation of ruthenium-catecholate complexes from ruthenium trichloride and bidentate ligand catechol ( Table 5, run 4). [34][35][36] In addition, under the same conditions (Ru 6 mol%, 240 8C, 3-5 h), Ru/A-H 3 PO 4 was effective in the HDO of more complicated branched phenols with hydroxyl and alkoxy groups, affording cyclohexane in high to medium yields ( Table 5, runs 5-11). Moreover, with the optimized reaction conditions, a series of representative bioderived phenolic monomers, the most abundant aromatic units originating from bio-oil, were efficiently converted to hydrocarbons as well ( Table 5, runs 12-18).…”

Structure and Ultrafast Dynamics of the Charge-Transfer Excited State and Redox Activity of the Ground State of Mono- and Binuclear Platinum(II) Diimine Catecholate and Bis-catecholate Complexes: A Transient Absorption, TRIR, DFT, and Electrochemical Study

“…Excitation with a 395 nm, ∼120 fs pulse resulted in an instantaneous bleach Figure 12. TRIR data obtained in CH 2 Cl 2 following excitation with a 400 nm, ∼150 fs laser pulse: (a) a series of TRIR spectra for the mononuclear complex 5, recorded at -50, 1, 2, 3, 7, 35, 100, 200, 400, and 1000 ps time delays after the laser pulse; (b) a series of TRIR spectra for the binuclear complex 2, recorded at 2, 3, 7, 15,35,75,200, and 400 ps time delays after the laser pulse; (c) initial parts of the kinetic trace recorded at 1570 cm -1 , which demonstrate the presence of a grow-in component for 2, the parent bleach recovery of ν(CO) at 1639 cm -1 for 5, and the decay of the corresponding transient band at 1620 cm -1 for 5.…”

Effects of Countercations on the Structures and Redox and Spectroscopic Properties of Diruthenium Catecholate Complexes with Ligand-Unsupported Ru−Ru Bonds

“…The Na + cations are further chelated by DME (1b) or coordinated by THF (2b s ), exhibiting a distorted octahedral or tetrahedral coordination geometry. On the other hand, the second mode, called the "out-of-plane connection", was found in [Na (THF) 11,12 (Figure 1b). The Na The connecting structures of the Na + cations to the [Ru 2 (R 4 Cat)] 2-/3units are among the fascinating features of the present complexes, especially for the development of molecular assemblages based on cation‚‚‚anion interactions.…”

“…6 On the other hand, the effects of cations on structures and physical properties in the solid state and solution have been less well-described for dimetallic com- plexes accompanying by countercations represented by [M 2 X 8 ] n-(X ) halogen atom), 7 [M 2 (CO 3 ) 4 ] n-, 8 [M 2 (SO 4 ) 4 ] n-, 9 and [M 2 (HPO 4 ) 4 ] n-. 10 In the preceding paper of this series, 11 we reported the synthesis and the structural and physicochemical diversity of a variety of diruthenium complexes, generally formulated as [Na n {Ru 2 (R 4 Cat) 4 }] (n ) 2 or 3; R 4 ) F 4 , Cl 4 , 12 Br 4 , H 4 , 3,5-di-t-Bu, and 3,6-di-t-Bu), and clearly demonstrated that the complexes with ligand-unsupported Ru-Ru bonds can sensitively respond to redox reactions and ligand substituents on the basis of the greater degree of freedom in their molecular structures. Although special attention had not been paid to the interaction between the [Ru 2 (R 4 Cat) 4 ] 2-/3units and countercations in the literature, the countercations, Na + , bind to the O Cat atoms of R 4 Cat 2in all of the complexes.…”

“…We describe the effect of countercations on the molecular structures and physical properties of dinuclear complexes to give a new route for developing the usefulness of the M-M-bonded system as a molecular building block. 11 and [Na 2 {Ru 2 (3,6-DTBCat) 4 }] (2b) 11 were synthesized by literature methods. The other chemicals were purchased from Aldrich Chemical Co. (1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6)), Tokyo Chemical Industry Co., Ltd. (3,5-di-tert-butylcatechol (3,5-DTBCatH 2 ) and tetra-n-butylammonium hexafluorophosphate (n-Bu 4 NPF 6 )), Wako Pure Chemical Industries, Ltd. (lithium hydroxide monohydrate (LiOH‚H 2 O), Nacalai Tesque, Inc. (sodium hydroxide (NaOH) and potassium hydroxide (KOH)), and Kanto Kagaku (rubidium hydroxide (RbOH)).…”