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Di Credico B, Fabrizi de Biani F, Gonsalvi L, Guerri A, Ienco A, Laschi F, Peruzzini M, Reginato G, Rossin A, Zanello P: Cyclopentadienyl ruthenium (II) complexes with bridging alkynylphosphine ligands: synthesis and electrochemical studies. Chemistry. 2009 Nov 9;15(44):11985-98.
The reaction of [CpRuCl (PPh (3))(2)] (Cp = cyclopentadienyl) and [CpRuCl (dppe)] (dppe = Ph (2) PCH (2) CH (2) PPh (2)) with bis- and tris-phosphine ligands 1,4-(Ph (2) PC [triple bond] C)(2) C (6) H (4) (1) and 1,3,5-(Ph (2) PC [triple bond] C)(3) C (6) H (3) (2), prepared by Ni-catalysed cross-coupling reactions between terminal alkynes and diphenylchlorophosphine, has been investigated. Using metal-directed self-assembly methodologies, two linear bimetallic complexes, [{CpRuCl (PPh (3))}(2)(mu-dppab)] (3) and [{CpRu (dppe)}(2)(mu-dppab)](PF (6))(2) (4), and the mononuclear complex [CpRuCl (PPh (3))(eta (1)-dppab)] (6), which contains a "dangling arm" ligand, were prepared (dppab =1,4-bis [(diphenylphosphino) ethynyl] benzene). Moreover, by using the triphosphine 1,3,5-tris [(diphenylphosphino) ethynyl] benzene (tppab), the trimetallic [{CpRuCl (PPh (3))}(3)(mu (3)-tppab)] (5) species was synthesised, which is the first example of a chiral-at-ruthenium complex containing three different stereogenic centres. Besides these open-chain complexes, the neutral cyclic species [{CpRuCl (mu-dppab)}(2)] (7) was also obtained under different experimental conditions. The coordination chemistry of such systems towards supramolecular assemblies was tested by reaction of the bimetallic precursor 3 with additional equivalents of ligand 2. Two rigid macrocycles based on cis coordination of dppab to [CpRu (PPh (3))] were obtained, that is, the dinuclear complex [{CpRu (PPh (3))(mu-dppab)}(2)](PF (6))(2) (8) and the tetranuclear square [{CpRu (PPh (3))(mu-dppab)}(4)](PF (6))(4) (9). The solid-state structures of 7 and 8 have been determined by X-ray diffraction analysis and show a different arrangement of the two parallel dppab ligands. All compounds were characterised by various methods including ESIMS, electrochemistry and by X-band ESR spectroscopy in the case of the electrogenerated paramagnetic species. |
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