Cyclopentadienyl ruthenium(II) complexes with bridging alkynylphosphine ligands: synthesis and electrochemical studies.
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.
Istituto di Chimica dei Composti OrganoMetallici, Consglio Nazionale delle ricerche CNR via Madonna del Piano 10, 50019 Sesto Fiorentino, Florence, Italy.
Barbara
B
Di Credico
Fabrizia
F
Fabrizi de Biani
Luca
L
Gonsalvi
Annalisa
A
Guerri
Andrea
A
Ienco
Franco
F
Laschi
Maurizio
M
Peruzzini
Gianna
G
Reginato
Andrea
A
Rossin
Piero
P
Zanello