FULL PAPER DOI: 10.1002/ejic.200601050 A Trinuclear Aqua Cyano-Bridged Ruthenium Complex [{(η 5 -C 5 H 5 )(PPh 3 ) 2 - Ru(μ-CN)} 2 RuCl 2 (PPh 3 )(H 2 O)]PF 6 : Synthesis, Characterization and Crystal Structure Viatcheslav Vertlib, [a] João Figueira, [a] José Mesquita, [a] João Rodrigues,* [a] Kalle Nättinen, [b][‡] and Kari Rissanen* [b] Keywords: Ruthenium / Trinuclear complexes / Bridging ligands / X-ray structure / Metal–metal interactions / Chain structures The organometallic trinuclear aqua cyano-bridged complex [{(η 5 -C 5 H 5 )(PPh 3 ) 2 Ru(μ-CN)} 2 RuCl 2 (PPh 3 )(H 2 O)]PF 6 (1), in which the fragment [RuCl 2 (PPh 3 )(H 2 O)] acts as a bridge and an acceptor group between the two terminal cyclopen- tadienyl ruthenium cyano moieties, was isolated in moderate yield from the reaction of [(η 5 -C 5 H 5 )(PPh 3 ) 2 RuCN] with [RuCl 2 (PPh 3 ) 3 ] in THF. To the best of our knowledge, com- pound 1 is one of the few examples of a trinuclear array of ruthenium fragments bridged by the nitrogen atom of the –CN– group (Ru–CN–Ru'–NC–Ru) with a Ru-coordi- Introduction Because of their interesting properties (such as conduc- tivity, magnetic and spectral properties), di- and trinuclear complexes with bridging cyanide ligands have been widely studied and have been the object of a large number of publi- cations in the last decades. [1] However, the number of trinu- clear complexes reported is less than half of that reported for dinuclear cyanide-bridged complexes, because of diffi- culties in controlling the synthesis and the ease with which coordination polymers are formed. [2] The bonding charac- teristics of the cyanide anion make it a good donor at both its C and N atoms [3] – the C atom has a greater affinity for electron-rich metals (such as M II ), while the N atom for electron-deficient metals (such as M III ). The ability of the cyanide anion to bridge two metal centers and to mediate electronic communications between metal atoms (e.g. elec- tron transfer) [4] led us recently to prepare and determine the [a] Centro de Química da Madeira, LQCMM/MMRG, De- partamento de Química da Universidade da Madeira, Campus de Penteada, 9000-390 Funchal, Portugal E-mail: joaor@uma.pt [b] Nanoscience Center, Department of Chemistry, University of Jyväskylä, P. O. Box 35, 40014 Jyväskylä, Finland E-mail: krissane@cc.jyu.fi [‡] Present address: VTT Processes, P. O. Box 1607, 33101 Tampere, Finland Supporting information for this article is available on the WWW under http://www.eurjic.org or from the author. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Eur. J. Inorg. Chem. 2007, 1920–1924 1920 nated water molecule. The new aqua complex was structur- ally characterized by FTIR, 1 H, 13 C, and 31 P NMR spec- troscopy, mass spectrometry, elemental analysis, single-crys- tal X-ray diffraction, and cyclic voltammetry. The title com- plex crystallizes in a triclinic unit cell a = 17.3477(6) Å, b = 17.8551(5) Å, c = 18.2460(7) Å, α = 95.693(2)°, β = 111.648(2)°, and γ = 97.839(2)° in the space group P1 ¯ with Z = 2. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) X-ray structure of the dinuclear ruthenium cyano-bridged organometallic complex [(η 5 -C 5 H 5 )(PPh 3 ) 2 Ru(μ-CN)- Ru(PPh 3 ) 2 (η 5 -C 5 H 5 )]PF 6 . [5] As a natural extension of our previous work, we explored the properties of the –CN– bridging group in trinuclear complexes with linear arrays of ruthenium fragments (Ru–CN–Ru'–NC–Ru). Vahren- kamp et al. [4c,6] have systematically studied such trinuclear complexes, focusing mainly on the effects of the geometry and the oxidation state at the central metal and of the ori- entation of the bridges (cyanide vs. isocyanide) on the elec- tronic communication between two terminal metallic frag- ments. Furthermore, while water is a very common ligand in classical Werner-type coordination chemistry, in 18-elec- tron organometallic complexes coordinated water is rela- tively rare. This has two main reasons: (a) in organometallic compounds, the metal centers do not display either “hard” or “soft” character, (b) the oxygen atom has a hard donor capacity and binds weakly to most low-valent transition metals like Ru II . [7] These labile complexes are frequently used as precursors for catalysts in organic reactions and in biological applications, viz. aqua complexes of ruthenium have proved to be effective for ring-opening metathesis po- lymerization (ROMP) [8] and as anti-tumor compounds. [9] In this paper, we report the preparation, structural characteri- zation, and X-ray structure of a rare example of an organo- metallic trinuclear cyano-bridged ruthenium complex with Ru-coordinated water.