Aspects of Aqueous Ruthenium(II) Chemistry

Abstract

Dedicated to the memory of Professor Luigi M. VenanziSince the first facile synthesis of [Ru(H 2 O) 6 ](tos) 2 was published at the beginning of the eighties, several Ru II aqueous inorganic and organometallic complexes were described, showing the increasing interest in this kind of compound due to potential applications in catalysis and medicine. To understand what governs the reactivity of the ligands in the first coordination sphere of the Ru II center, we discuss its solution behavior, starting with the simplest aqueous species [Ru(H 2 O) 6 ] 2 and moving progressively in complexity with selected examples. In addition, we present variable-pressure measurements with two objectives: to determine activation volumes for mechanistic assignments, and to shift equilibria by increasing the solubility of gaseous molecules.1. Introduction. ± Interest in aqua complexes of Ru II has increased over the past few years. First, from a synthetic viewpoint, Ru II shows an ideal compromise between softness and acidity of complexed H 2 O, and back-bonding into p* orbitals of carbon p ligands. This property allows us to envisage promising research in organometallic chemistry of Ru II in H 2 O. Since its facile synthesis, [Ru(H 2 O) 6 ](tos) 2 is an ideal starting material for a series of new aqua complexes with ligands as varied as N-heterocycles, phosphines, arenes, and olefins, and small gaseous molecules such as H 2 , N 2 , CO, and H 2 CCH 2 .Second, Ru II aqua complexes are key intermediates in the metabolic processes associated with the antitumor reactivity of Ru II compounds. Aqua complexes of Ru II have also an important catalytic activity for the polymerization and isomerization of olefins.To understand what governs the reactivity of the ligands in the first coordination sphere of the Ru II center, we will discuss its solution behavior starting with the simplest aqueous species [Ru(H 2 O) 6 ] 2 and moving progressively in complexity with selected examples.In addition, we will present variable-pressure measurements with two objectives: to determine activation volumes for mechanistic assignments, and to shift equilibria by increasing the solubility of gaseous molecules.

Mechanistic information on the reaction of cis- and trans-[RuCl2(DMSO)4] with d(T2GGT2) derived from MALDI-TOF and HPLC studies☆

“…This observation implies that removal of chloride occurs prior to, or during the binding of d(T 2 GGT 2 ) to Ib. Although detailed studies on the intimate reaction mechanism were not performed, it may be expected on the basis of literature data on similar ruthenium(II) complexes [24,25] that coordination of guanine bases occurs via dissociative (D) or dissociative interchange (I d ) mechanism, i.e., by aquation of chloride followed by coordination of oligonucleotide, or by simultaneous release of chloride and coordination of oligonucleotide, respectively.…”

Synthesis and Characterization of New Water‐Soluble Hydrides of RuII: A Step towards Dinitrogen Activation?

“…was then pressurized with N 2 /H 2 mixture (1 : 1; total pressure is 100 bar) and shaken for 12 h at r.t. After the gas pressure was removed, the water was evaporated under vacuum, and the pale yellow powder was dried under 10 À4 bar overnight. 1 We thank the Swiss National Science Foundation and the Swiss State Secretariat for Education and Science for financial support.…”

“…A solution of [RuH(TPPTS) 2 (H 2 O) 3 ] 2 was pressurized overnight with CO and H 2 (1 : 1; total pressure is 100 atm) at room temperature in a sapphire NMR tube, the previously orange solution turned in a very pale yellow one. 1 H-NMR Spectra showed deshielding of the À 9.6 and À 9.7 ppm hydride signals to À 6.44 and À 6.45 ppm, respectively ( Fig. 3).…”

“…4), it revealed 2 J(H,CO) 36 and 2 J(H,P) 18 Hz, and 13 C-NMR spectra confirmed the 1 H-NMR results. Second, the pressurization of 15 N 2 into this system leads to the appearance of 15 N 2 satellite signals in 1 H-NMR spectra (Fig. 5).…”

“…Introduction. ± Interest in the chemistry water-soluble complexes of Ru II has increased over the past few years due to potential applications in catalysis [1] and medicine [2]. Ru II aqua ions show an ideal compromise between softness and acidity of coordinated H 2 O and back-bonding into p* orbitals of carbon p ligands [3].…”