Oligomerisation of alkynes at a diruthenium centre

Abstract

The Ru=Ru double-bonded p-alkynecomplexes [Ru,(p-CO)(p-RC,R)(q-C5H5),] ( R = Ph or CF,) react in heptane or xylene at reflux with alkynes R'CECR' (R' = C0,Me or CF,) to link up to four molecules of alkyne; the structures of the complexes [ R U , ( C O ) { ~-C , ( C F , ) , ) ( ~-C ~H ~) ~] (two isomers) and [Ru,{p-C,(CF,),(CO,Me),}(q-C,H,),],which contains a C, ring with a C, 'tail', have been established by X-ray diffraction.

Synfacially Structured [(CpRu)2μ-cot]—What a Difference the Coordination Side Makes!

“…[5] The linkage of four alkyne units was indeed successful, but the formation of a cyclooctatetraene complex failed; thermally induced ring closure reactions of an open chain C 8 unit to a cot ligand in dinuclear complexes were only successful for a dichromium complex. [6] In addition to this area of research, which is of substantial importance for the oligomerization of hydrocarbons at metal centers, we hoped that a better understanding of the metal ± metal interaction and the coordination mode of the cot ligand would emerge.…”

“…In all the dinuclear complexes, the two metal centers are synfacially coordinated at the cot ligand. Complexes 2 a and 3 a show a h 4 :h 4 bonding mode of the cot moiety, whereas, upon oxidation, the cot ligand in 3 a changes its hapticity to h 5 :h 5 . Results from 1 H NMR spectroscopic studies of 2 a, 2 b and [3 a] 2 are in accordance with the crystallographic findings, in contrast to the neutral complex 3 a, which shows a fast rotation of the cot entity even at 200 K. The RuÀRu distances in the dinuclear complexes decrease dramatically from 307.8 pm in 2 a to 266 pm in [3 a] 2 ; complexes 3 a and [3 a] have RuÀRu bond lengths of 295.6 and 282.2 pm, respectively.…”

Cyclometallation of bis(diphenylphos-phino)methane ligands on a binuclear ruthenium(0) carbonyl complex

“…The Ru-Ru distance at 2.933 (2) A is within the bonding range (9) and is slightly longer than in the parent complex [Ru,(CO)~(~-CO)(p-dppm),], 1, which has Ru-Ru (3) by 0.24(2) A). The dihedral angle between the above two planes is 50.7(6)", which clearly indicates a very significant twist.…”

Carbon–carbon coupling on tetrahedral iridium clusters: X-ray molecular structures and multinuclear NMR studies of the two isomeric forms of [Ir4(CO)6(μ3-η2-HCCPh)(μ2-η4-C4H2Ph2)(μ-PPh2)2]

“…This ligand is bonded in a r-fashion to Ir(4) to form a metallacyclopentadiene [Ir(4)-C(15) 2.051 (14), 3, 2.066(9) Å , 4 and Ir(4)-C(18) 2.096(13), 3, 2.092(9) Å , 4] that p-interacts with Ir(1) via all its carbon atoms as in the well known ferroles or ferracyclopentadiene complexes [36] and other dimers [37,38] and cluster compounds [39]. As such these ligands act formally as 6 electron donors.…”