Preparation of a New Ruthenium Formato Complex

Abstract

Several ruthenium acetato complexes have been prepared by various methods.,-3) Recently, T. A.Stephenson and G. Wilkinson prepared crystalline complexes with the formula Ru2(OCOR)4Cl, (R= Me, Et, n-Pr) ; those complexes contain two ruthenium atoms of the formal oxidation state of II and 111.3) These complexes have high magnetic moments over the temperature range of 300-100°K and appear to be the first spin-free complexes of ruthenium.We have prepared independently the formato and acetato complexes of ruthenium, Ru2(HOCO)4-Cl and Ru2(CH3OCO)4X (X=C1, Br, I),4) by the reaction in a sealed tube of ruthenium (III and IV) chloride with formic and acetic acid solutions respectively.The formato complex prepared is a black-brown crystal and is not dissolved in any common organic solvents except the alcohols. The infrared spectra of this complex are similar to those of hydrous Cu(II) formate.s) However, the absorptions of the carboxyl-stretching vibrations of the ruthenium formato complex shift to a lower wave number region compared with those of Cu(II) formate.in an acetato complex where acetate functions as a bidentate-bridging group may be expected not to be greatly different from that in a free acetate 150 cm-1) suggests that the complex has four bidentate formates. No absorptions due to the OH or the OH2 group were found in the infrared spectra. The magnetic moment of this complex is 2.92 B.M. per ruthenium atom. This value is similar to those for Ru2(CH3OC0)4X4) and Ru2-(OCOR)4C13) at room temperature and is higher than the magnetic moments of ruthenium d5 spinpaired complexes.7) These findings, along with the molecular weight, suggest a dimer structure, Ru2(HOCO)4C1, for the formato complex prepared; the complex is considered to be of a type similar to the acetato complex previously reported.3)Experimental. Ruthenium trichloride trihydrate (300 mg) was dissolved in 3 M formic acid (5 ml) and was gently heated for about 60 min in a sealed tube. The solution thus obtained was transferred to a porcelain dish and concentrated on a water bath to produce crystals. The crude product was dissolved in a 3 M formic acid solution; this solution was evaporated at room temperature for several days to obtain the crystalline product. The crystals were washed with water and ethanol in turn, and dried in vacuo.

Ruthenium Compounds

“…More specifi cally, Ru 2 (2-Fap) 4 Cl reacts with NO to form the axial NO-adduct Ru 2 (2-Fap) 4 Cl(NO) in which the bridging ap ligands adopt the (3,1) arrangement in order to minimize the steric repulsions with the phenyl substituents. 120 Finally, the complex Ru 2 (O 2 CMe) 2 (ap) 2 Cl(Hap) reacts with dmpm in the presence of Me 3 SiCl and NaBPh 4 to form the Ru 2 4+ compound [Ru 2 (ap) 2 (dmpm) 2 Cl]BPh 4 , which is the only crystallographically characterized Ru 2 4+ compound with bridging aminopyridinate ligands. 121 Cyclic voltammetry measurements of Ru 2 5+ tetraaminopyridinates show that their electrochemical behavior is strongly infl uenced by the solvent.…”

“…The reaction of Ru 2 (O 2 CMe)(DPhF) 3 Cl with p-(n-decyloxy)benzoic acid results in Ru 2 (O 2 CC 6 H 4 -p-OC 10 H 21 )(DPhF) 3 Cl, 130 whereas the reaction of Ru 2 (O 2 CMe)(DAniF) 3 Cl with the dicarboxylic acid 1,4-HO 2 CC 6 H 4 CO 2 H gives the molecular pair [Ru 2 (DAniF) 3 Cl](µ-O 2 CC 6 H 4 CO 2 )[Ru 2 (DAniF) 3 Cl]. 129 In an analogous way, cis-Ru 2 (O 2 CMe) 2 (DAniF) 2 Cl reacts with the dicarboxylic acids HO 2 CCO 2 H and HO 2 CC 6 H 4 CO 2 H to form the molecular squares {[cis-Ru 2 (DAniF) 2 Cl](µ-O 2 CCO 2 )} 4 ( Fig. 9.17) and {[cis-Ru 2 (DAniF) 2 Cl](µ-O 2 CC 6 H 4 CO 2 )} 4 , respectively.…”

“…129 In an analogous way, cis-Ru 2 (O 2 CMe) 2 (DAniF) 2 Cl reacts with the dicarboxylic acids HO 2 CCO 2 H and HO 2 CC 6 H 4 CO 2 H to form the molecular squares {[cis-Ru 2 (DAniF) 2 Cl](µ-O 2 CCO 2 )} 4 ( Fig. 9.17) and {[cis-Ru 2 (DAniF) 2 Cl](µ-O 2 CC 6 H 4 CO 2 )} 4 , respectively. 128 Cyclic voltammetry measurements of Ru 2 (DArF) 4 Cl complexes show a reversible, one electron, metal-based oxidation process and an irreversible reduction process, which correspond to Ru 2 5+ Ru 2 6+ + eand Ru 2 5+ + e -Ru 2 4+ , respectively.…”

“…125 Room temperature magnetic susceptibility measurements for complexes with a mixed set of bridging formamidinate/acetate ligands have also corresponded to the 2 4 2 ( * *) 3 electronic confi guration. [127][128][129] In the case of the molecular squares {[cis-Ru 2 (DAniF) 2 Cl](µ-O 2 CCO 2 )} 4 and {[cis-Ru 2 (DAniF) 2 Cl](µ-O 2 CC 6 H 4 CO 2 )} 4 variable temperature magnetic susceptibility studies show that in the square with the shorter oxalate bridges there is a weak antiferromagnetic coupling between the Ru 2 5+ units ( ~ -5 K), while in the terephthalate analog the coupling is negligible. 128 Analogously, no coupling was observed between the two Ru 2 5+ units in the compound [Ru 2 (DAniF) 3 Cl](µ-O 2 CC 6 H 4 CO 2 )[Ru 2 (DAniF) 3 Cl].…”

“…Complexes of the type [Ru 2 (O 2 CMe) 2 (5-Rsalpy) 2 ]have been synthesized from the reactions of Ru 2 (O 2 CMe) 4 Cl with the dianionic, tridentate ligands 5-Rsalpy (R = H, Me, Cl, Br, NO 2 ) in 1:2 ratio. 139,140 In the solid state, these complexes are isolated by using K + or Na + (18-crown-6) as counter-cations, and they display either discrete paddlewheel structures (Fig.…”