Tail-to-tail carbon–carbon bond coupling of acetylides on chalcogen-bridged Fe/W mixed-metal clusters

Synthesis, structure and electrochemistry of acetylide-bridged mixed metal cluster [Fe2(CO)6(μ3-S)2W{(η5-C5H5)W(CO)3(CCPh)}2]

“…The acetylide groups remain uncoupled. This is in marked contrast to the related reactions in which the adding acetylide units undergo decarbonylation and coupling between the acetylide groups with or without CO is observed [16]. Attempts to induce coupling between the acetylide groups of 3 by photolysis or thermolysis resulted in decomposition.…”

“…Nature of the chalcogen bridges, the metal acetylide used, and the reaction conditions used in these reactions all appear to play important roles in influencing the course of such acetylide couplings. We have observed coupling with and without CO as well as oxocontaining metal acetylide complexes when the reactions have been performed under aerobic conditions [16][17][18]. In this paper we report the formation of an unusual acetylide-containing mixed-metal cluster from a mild thermolysis reaction, its structural characterisation and investigation of its electrochemistry (Scheme 1).…”

X-ray molecular structures and multinuclear NMR studies of the tetranuclear iridium clusters [Ir4(CO)7(μ4-η3-PhCC(H)CCPh)(μ-PPh2)3] and [Ir4(CO)7(μ3-η2-HCCPh)(η1-CCPh)(μ-PPh2)3]

“…Solution NMR spectra were recorded on a Varian Inova-500, Bruker AMX 500, AC 300P or AC 200 spectrometers. Signals were attributed based on the following NMR experiments: 1 H, 13 C, 31 P, NOE, DEPT-90, 2D-HSQC; standard pulse sequences were used for the experiments. Hydrogen, carbon and phosphorus atoms were labeled as in the crystal structures.…”

“…[Ru 5 (l 5 -g 4 -CPhCCPhC)(l-SEt) 2 (CO) 13 ] and [Ru 6 (l 6 -g 4 -MeC 4 -Me)(l-SEt) 2 (CO) 10 ] as the result of head-to-tail and head-to-head couplings, respectively, of two acetylide units [1] and (iii) mononuclear metal acetylide compounds that were shown to undergo condensation with cluster compounds, e.g. [M(g 5 -C 5 Me 5 )(CO) 3 (C"CPh)] and [M(g 5 -C 5 H 5 )(CO) 3 (C"CPh)] (M = Mo or W) with [Fe 3 (CO) 9 (l 3 -E) 2 ] (E = S, Se or Te) under thermolytic conditions to yield high nuclearity heterometallic clusters containing C 4 ligands, including that resulting from the rare head-to-head acetylide condensation process [12,13].…”

“…Other sources of acetylide fragments for condensation in the coordination sphere of late transition metal clusters include: (i) the P(C"C t Bu) 3 ligand in [Ru 3 -(CO) 11 {P(C"C t Bu) 3 }], whose mild thermolysis led to the formation of [Ru 3 (l 3 -g 2 -C"C t Bu) 2 {l-P(C" C t Bu 2 ) 2 }(CO) 9 ] and then to the diyne tetranuclear compound [Ru 4 (l 4 -g 4 -t BuC 4 t Bu)(CO) 10 ] [11]; (ii) RC"CSEt (R = Me, Ph) that was heated in the presence of [Ru 3 (CO) 12 ], leading to several products of various nuclearities containing C 4 ligands, e.g. [Ru 5 (l 5 -g 4 -CPhCCPhC)(l-SEt) 2 (CO) 13 ] and [Ru 6 (l 6 -g 4 -MeC 4 -Me)(l-SEt) 2 (CO) 10 ] as the result of head-to-tail and head-to-head couplings, respectively, of two acetylide units [1] and (iii) mononuclear metal acetylide compounds that were shown to undergo condensation with cluster compounds, e.g.…”