ZUSCHRIFTEN Angew.Chem. 2000, 112, Nr. 22 WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2000 0044-8249/00/11222-4217 $ 17.50+.50/0 4217 Evidence for the Formation of a Ru III Ru III Bond in a Ruthenium Corrole Homodimer** François Je Âro Ãme, Be Âatrice Billier, Jean-Michel Barbe, EnriqueEspinosa,SlimaneDahaoui,ClaudeLecomte,* and Roger Guilard* The formation of a ruthenium ii ) porphyrin homodimer was first mentioned by Whitten and co-workers in 1975. [1] Never- theless, the interaction between the two metal centers has been fully evidenced only in 1984 on the basis of an X-ray structure determination of [{Ruoep)} 2 ]. [2, 3] It was shown later that this type of ruthenium porphyrin homodimer can be involved in several catalytic reactions as well as in the coordination of gaseous molecules such as ethylene and carbon monoxide. [4, 5] Furthermore, these complexes are extremely air-sensitive and the one- or two-electron chemical or electrochemical) oxidation of the dimer easily leads to the formation of the Ru II /Ru III and Ru III /Ru III species, respective- ly. [6] However, until now, no bisruthenium iii ) porphyrin homodimer has been obtained by a direct insertion of the Ru III cation into the porphyrin cavity. To study the reactivity of tetrapyrrole metal complexes in high oxidation states, we focused on the synthesis and characterization of corrole metal complexes. [7±9] Indeed, the corrole macroring possesses a small four-nitrogen cavity because of the presence of only three meso carbon atoms) and three NH groups which enhance the stabilization of metal cations in a high oxidation state. [10±12] Although as many as 18 different metal±corrole species are known, ruthenium corroles have never been synthesized. Moreover, many unsuccessful attempts have been made to metalate a corrole with ruthenium iii ). [13] Starting from RuCl 3 in dimethylforma- mide, Boschi et al. observed an insertion of a carbonyl group from the solvent into the pyrrole ± pyrrole bond leading, after rearrangements, to a ruthenium iii ) porphyrin. The same behavior was noted when using [Ru 3 CO) 12 ] in 2-methoxy- ethanol, again a carbonyl group insertion, this time from the metal carbonyl complex, occurred affording a ruthenium iii ) porphyrin. [13] We have also attempted the metalation reaction of H 3 hedmc) [3, 14] 1) with RuCl 3 in carbonyl group free solvents with different boiling points, such as pyridine, xylene, benzonitrile and trichlorobenzene. No metalation reaction was noted after 72h at reflux. The complex [{cod)RuCl 2 } 2 ] [3] does not bear a carbonyl group and is more reactive than RuCl 3 in many metalation reactions. [15] This Ru II dimer is easily synthesized by the reaction of hydrated RuCl 3 with cod [3] in boiling ethanol for 12 h. The reaction of 1 with an excess [{cod)RuCl 2 } 2 ] was carried out in refluxing 2-methoxy- ethanol with the presence of a trace amount of triethylamine see Experimental Section). Triethylamine prevents the pro- tonation of 1 by the HCl evolved during the metalation reaction. Furthermore, the reaction is easily carried out in an air atmosphere which enhances the oxidation of Ru II to Ru III necessary to form [{Ruhedmc)} 2 ]2, Scheme 1). [16] Scheme 1. The formation of [{Ruhedmc)} 2 ]; a) [{cod)RuCl 2 } 2 ], 2-me- thoxyethanol, triethylamine, reflux, 30 min. By UV/Vis spectroscopy one can observe after 30 min of reaction the disappearance of the Q bands of the starting free base corrole and a large blue shift of the Soret band from 396 to 336 nm Figure 1). The formation of 2 is demonstrated by both the presence in the MALDI/TOF matrix assisted laser desorption/ionization time of flight) mass spectrum of a peak pattern in the expected region largest peak at 1186.53) [16] and the results of a single- crystal X-ray diffraction study. [17] No trace of a monomeric species is evidenced by mass spectrometry, thus confirming the presence of the pure, strongly bound dimer 2. Figure 2a shows the molecular structure of 2 at T 1122) K. In spite of the low-temperature X-ray diffraction measurements the atomic thermal parameters are quite large, resulting probably from a rotation of the dimer around the Ru Ru axis. As [20] J. Fajer, M. S. Davis in The Porphyrins , Vol.IV Ed.: D. Dolphin), Academic Press, New York, 1979, pp. 197 ± 256. [21] M. Gouterman in The Porphyrins , Vol.III Ed.: D. Dolphin), Academic Press, New York, 1979,pp.1±165. [22] Z. Gross, N. Galili, Angew.Chem. 1999, 111, 2536; Angew.Chem.Int. Ed. 1999, 38, 2366. [23] L. Simkhovich, I. Goldberg, Z. Gross, J.Inorg.Biochem. 2000, 80, 235. [24] For a high quantum yield for a corrole derivative in which one of the corrole nitrogen atoms is replaced by oxygen an oxacorrole), see: S. J. Narayanan, B. Sridevi, T. K. Chandrashekar, U. Englich, K. Ruhlandt- Senge, Org.Lett. 1999, 1, 587. [25] Measurements were made on solutions of the sample 50nm) in oxygen-free toluene degassed by five freeze-pump-thaw cycles) under Ar. For a description of the experimental setup for the triplet-lifetime measurements, see: I. J. Dmochowski, J. R. Winkler, H. B. Gray, J.Inorg.Biochem. 2000, 81, 221. [*] Prof. Dr. R. Guilard, F. Je Âro Ãme, B. Billier, Dr. J.-M. Barbe, Dr. E. Espinosa LIMSAG, UMR 5633, Universite  de Bourgogne Faculte  des Sciences ªGabrielº 6 Boulevard Gabriel, 21100 Dijon France) Fax: 33)3-8039-6117 E-mail: roger.guilard@u-bourgogne.fr Prof. Dr. C. Lecomte, Dr. S. Dahaoui LCM3B, Universite  Henri Poincare  Boulevard des Aiguillettes BP 239, 54506 Vandoeuvre-les-Nancy France) Fax: 33)3-8340-6492 E-mail: lecomte@lcm3b.u-nancy.fr [**] This work was supported by the CNRS. F.J. gratefully acknowledges the ªRegion Bourgogneº and Air Liquide for a financial support. The authors also thank Mr. M. Soustelle for technical assistance. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/home/angewandte/ or from the author.