Synthesis and Characterization of Diruthenium Complexes in Low Oxidation States. Formation of Mono- and Bis-CO Adducts

Abstract

A monocarbonyl diruthenium(II,II) complex of the type (dpf)4Ru2(CO), where dpf is N,N‘-diphenylformamidinate, was characterized as to its electrochemical and spectroscopic properties (UV−vis, FTIR, and ESR) under a N2 or CO atmosphere. The synthesis and X-ray structural characterization of (dpf)4Ru2(CO) are also presented.

Structural, spectroscopic and theoretical studies of a diruthenium(II,II) tetraformamidinate that reversibly binds dioxygen

“…The reversible reaction with dioxygen suggests that it is axially binding to the complex, rather than generating mono-or di-nuclear oxo products. This is similar to the observed reactivity of diruthenium tetraformamidinate with CO previously by reported by Bear and Kadish [10,15].…”

“…However, diruthenium paddlewheel compounds supported by N,N donor ligands are more resistant to decomposition. For example, Ru 2 (dpf) 4 Cl and Ru 2 (dpf) 3 (O 2 CMe)Cl (dpf = N,N'-diphenyformamidinate) react with one or two equivalents of NO (g) CO (dpb = N,N'-diphenylbenzamidinate) have been obtained [10,15]. They display long Ru-Ru bond distances (2.5544(8) Å and 2.4789(8) Å respectively) indicating that the σ 2 π 4 δ 2 π *4 electronic configuration has been retained by the diruthenium core.…”

Carbonyl and nitrosyl diruthenium compounds: Crystal structure of [Ru2(O2CMe)(DPhF)3(CO)]BF4·CH2Cl2 and its isomorphous nitrosyl analogue

“…The CO stretching vibration bands for the compound Ru 2 (DPhF) 4 (CO) and the electrochemically reduced species [Ru 2 (DPhF) 4 (CO)] À appear at 1929 and 1840 cm À1 , respectively. This difference is in agreement with the variation of the electron density in the metal centres and, consequently, with the back-donation to the carbonyl ligand [11].…”

“…The cationic species [Ru 2 (DPhF) 4 (CO)] + was detected in the electrochemical studies carried out on Ru 2 (DPhF) 4 (CO) in CH 2 Cl 2 solution [11], although the complex was not isolated. However, the easy coordination of CO at the axial position of [Ru 2 (O 2 CMe)(DPhF) 3 (H 2 O)]BF 4 in dichloromethane solution allows the isolation of [Ru 2 (O 2 CMe)(DPhF) 3 (CO)]BF 4 (1) in good yield.…”

“…The first stable carbonyldiruthenium complex Ru 2 (DPhF) 4 (CO) containing a Ru 2 4+ unit has four strongly basic equatorial ligands. This compound can be converted by oxidation in the analogous Ru 2 5+ derivative but this latter complex was not isolated [11].…”