Electronic Interactions in Iron- and Ruthenium-Containing Heterobimetallic Complexes:  Structural and Spectroscopic Investigations

Abstract

The heterobimetallic Ru complexes Cp(CO)Ru(μ-I)(μ-dppm)PtI2 (8), Cp(CO)Ru(μ-I)(μ-dppm)PdI2 (10), and Cp(CO)RuI(μ-dppm)AuI (12) and their isoelectronic Fe analogues Cp(CO)Fe(μ-I)(μ-dppm)PtI2 (9), Cp(CO)Fe(μ-I)(μ-dppm)PdI2 (11), and Cp(CO)FeI(μ-dppm)AuI (13) were prepared by the reactions of Cp(CO)M(κ1-dppm)I (6, M = Ru; 7, M = Fe) with Pt(COD)I2, Pd(COD)I2, and AuI, respectively. All six complexes were characterized by cyclic voltammetry, IR, UV, and NMR (1H and 31P) spectroscopy, and elemental analysis. The structures of the I-bridged compounds 8−11 were determined by X-ray crystallography. Electronic interaction between the two metals is significant for the iodide-bridged compounds 8−11, as evidenced by the variation in their carbonyl stretching frequencies and UV−vis spectra, as well as in the shifts of their redox potentials in comparison to the shifts for mononuclear model compounds. In contrast, compounds 12 and 13, which have only dppm bridges, exhibit limited interactions between the two metals.

Electrochemical oxidation of ethanol using Nafion electrodes modified with heterobimetallic catalysts

“…The Nafion ionomer was purchased as a 5% weight solution (1000 EW) in a mixture of isopropanol/H 2 O (75/20 v/v) and sparged with Ar before use. The complexes Cp(PPh 3 )Ru(l-I)(l-dppm)PdCl 2 (1) [17], [g 5 -C 5 H 4 CH 2 CH 2 (NHMe 2 ) + ]Ru(PPh 3 )(l-I)(l-dppm)PtCl 2 (2) [18], [g 5 -C 5 H 4 CH 2 CH 2 (NHMe 2 ) + ]Ru(PPh 3 )(l-Cl)(l-dppm)PdCl 2 (3) [18], Cp(CO)Fe(l-I)(l-dppm)PdI 2 (4) [19], and Cp(CO)Ru(l-I)(ldppm)PtI 2 (5) [19] were synthesized as previously reported in the literature.…”

“…The preparation and spectroscopic data for complexes 1-5 have been previously reported [17][18][19]. …”

“…1a) [17][18][19]22]. The first and third waves correspond to the II/III and III/IV oxidations of either Ru or Fe while the second wave represents the II/IV oxidation of the second metal (Pt or Pd).…”

“…We have previously reported electrocatalytic oxidation of methanol and ethanol in homogeneous solution using the organometallic catalysts Cp(PPh 3 )Ru(l-I)(l-dppm)PdCl 2 (1), [g 5 -C 5 H 4 CH 2 CH 2 (NHMe 2 ) + ]Ru(PPh 3 )(l-I)(l-dppm)PtCl 2 (2), [g 5 -C 5 H 4 CH 2 CH 2 (NHMe 2 ) + ]Ru(PPh 3 )(l-Cl)(l-dppm)PdCl 2 (3), Cp(CO)-Fe(l-I)(l-dppm)PdI 2 (4) and Cp(CO)Ru(l-I)(l-dppm)PtI 2 (5) [17][18][19][20]. In these complexes, the metals are linked through a 1,1 0 -bis(diphenylphosphino)methane (dppm) ligand which allows for a synergistic effect and increased reactivity of the complex when compared to mononuclear model compounds [18,21,22].…”

“…doi:10.1016/j.ica.2011.01.011 [30,[32][33][34][35]. This work investigates the electrochemical oxidation of ethanol using the previously prepared complexes Cp(PPh 3 )Ru(l-I) (l-dppm)PdCl 2 (1) [17], [g 5 -C 5 H 4 CH 2 CH 2 (NHMe 2 ) + ]Ru(PPh 3 )(l-I) (l-dppm)PtCl 2 (2) [18], [g 5 -C 5 H 4 CH 2 CH 2 (NHMe 2 ) + ]Ru(PPh 3 )(l-Cl) (l-dppm)PdCl 2 (3) [18], Cp(CO)Fe(l-I)(l-dppm)PdI 2 (4) [19], and Cp(CO)Ru(l-I)(l-dppm)PtI 2 (5) [19] immobilized on the working electrode by incorporation into Nafion films.…”