The synthesis, structure, reactivity and electrochemical properties of ruthenium complexes featuring cyanoacetylide ligands Richard L. Cordiner a , Mark E. Smith a , Andrei S. Batsanov a , David Albesa-Jove ´ a , Frantis ˇek Hartl b , Judith A.K. Howard a , Paul J. Low a, * a Department of Chemistry, University of Durham, South Road, Durham, DH1 3LE, UK b VanÕt Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV, Amsterdam, The Netherlands Received 19 May 2005; accepted 13 June 2005 Available online 15 August 2005 Ruthenium and Osmium Chemistry Topical Issue. Abstract The complex [Ru(C„CC„N)(dppe)Cp*] (1) is readily obtained (ca. 70%) from the sequential reaction of [Ru(C@CH 2 )(dp- pe)Cp*]PF 6 with n BuLi and phenyl cyanate. The complex behaves as a typical transition metal acetylide upon reaction with tetra- cyanoethene, affording a metallated pentacyanobutadiene. Complex 1 is a useful metalloligand, and its reactions with [W(thf)(CO) 5 ], [RuCl(PPh 3 ) 2 Cp], [RuCl(dppe)Cp*] or cis-[RuCl 2 (dppe) 2 ] all afforded products featuring the M–C„CC„N–M 0 motif, for which ground state structures indicate a degree of polarisation. Electrochemical and spectroelectrochemical studies reveal moderate inter- actions between the metal centres in the 35-electron dications [{Cp*(dppe)Ru}(l-C„CC„N){RuL 2 Cp 0 }] 2+ (RuL 2 Cp 0 = Ru(PPh 3 ) 2 Cp, Ru(dppe)Cp*). Ó 2005 Elsevier B.V. All rights reserved. Keywords: Ruthenium; Spectroelectrochemistry; Cyanide; Cyanocarbon 1. Introduction The continued interest in the fundamentals of the electron transfer processes, together with the potential for exploitation of controlled electron transfer processes in mixed-valence materials for modern materials appli- cations, and related magnetic and optical phenomena, has led to intense contemporary research effort in the synthesis and characterisation of metal complexes fea- turing two (or more) metal centres bridged by some li- gand that permits electronic effects to be passed between them. As a consequence, there has been some- thing of a renaissance in the chemistry of well-known ligands such as cyanide [1] and the diethynylaromatics [2], together with a ground-swell of studies dealing with metal-supported carbon chains [3] and the coordination chemistry of polyynes [4]. In this context, the cyanoacetylide ligand, [C„CC„N]  , is a potentially useful bridging moiety, being isoelectronic with the diyndiyl ligand and having obvious relationships with the ubiquitous cyanide li- gand. Although some [M(C„CC„N)L n ] type com- plexes have been prepared and structurally characterised [5], the development of this area has been handicapped by the paucity of synthetic routes to such species. Recently, we have prepared a metallocyanoacet- ylide complex [Ru(C„CC„N)(PPh 3 ) 2 Cp] from sequen- tial reaction of [Ru(C„CH)(PPh 3 ) 2 Cp] with n BuLi and PhOCN [6]. In the present paper, we detail the syntheses and molecular structures of [Ru(C„CC„N)(dppe)Cp*] 0020-1693/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2005.06.044 * Corresponding author. Tel.: +44 191 334 2114; fax: +44 191 384 4737. E-mail address: p.j.low@durham.ac.uk (P.J. Low). www.elsevier.com/locate/ica Inorganica Chimica Acta 359 (2006) 946–961