Dimethyl Acetylenedicarboxylate (dmad) Reactivity with the Mixed-Metal Cluster Co₂Rh₂(CO)₁₂:  Facile Cluster Fragmentation and Highly Specific Metal Redistribution to Give the Butterfly Cluster Co₃Rh(CO)₁₀(μ-dmad) and the Planar Cluster CoRh₃(CO)₉(μ-dmad)₃

Abstract

The reaction between the tetrahedral cluster Co 2 Rh 2 (CO) 12 (1) and a 2-fold excess of dimethyl acetylenedicarboxylate (dmad) proceeds rapidly at room temperature to give alkyne-substituted clusters Co 3 Rh(CO) 10 -(µ-dmad) (3) and CoRh 3 (CO) 9 (µ-dmad) 3 (4) as the major products in good yield. Cluster 3 was characterized in solution by IR and 1 H NMR spectroscopies and by comparison to an independently prepared sample of 3 from the reaction of dmad with the known tetrahedral cluster Co 3 Rh(CO) 12 (2). Cluster 4 was characterized by IR and NMR ( 1 H and 13 C) spectroscopies and FAB mass spectrometry, and the solid-state structure was established by X-ray diffraction analysis. The structure of CoRh 3 (CO) 9 (µ-dmad) 3 consists of a square planar array of metals where two of the three dmad ligands cap both of the CoRh 3 faces and the remaining dmad ligand bridges one of the Rh-Rh edges. The nine ancillary CO groups are all terminally bound, with one Co(CO) 3 and three Rh(CO) 2 moieties structurally found. The facile cluster fragmentation/metal redistribution observed upon reaction with dmad is briefly discussed relative to other alkyne ligands that react with cluster 1 to furnish the arachno clusters Co 2 Rh 2 (CO) 10 (µ 4 -alkyne).

Transformations of Triphenylgermyl Ligands in Iridium−Ruthenium Carbonyl Cluster Complexes

“…The entire (CH 3 O 2 C)C(CO 2 CH 3 )CGePh group serves a quadruply bridging ligand across all four metal atoms, and the alkyne C−C bond, C(1)−C(4), has lengthened to 1.448(9) Å due to the coordination. This C−C distance is similar to the C−C distances found for the quadruply bridging DMAD ligands found in the complex CoRh 3 (CO) 9 [μ 4 -(CH 3 O 2 C)C 2 (CO 2 CH 3 )] 2 [μ 4 -(CH 3 O 2 C)C 2 (CO 2 CH 3 )], 1.411(6) and 1.428(6) Å . The formation of germanium−carbon bonds is central to reactions such as the hydrogermylation of alkynes .…”

Cluster chemistry in the Noughties: new developments and their relationship to nanoparticles

“…Work by Richmond and co-workers highlights some of these issues. 149 This is a quite unexpected and astonishing result. The electronic nature of the transformation has been probed using methyl propiolate 150 and here .…”

Reaction of Alkynes with Rh4(CO)12. A Mid-Infrared Vibrational and Kinetic Study of (μ4-η2-alkyne)Rh4(CO)8(μ-CO)2

“…Shortly thereafter, Horvath reported the X-ray single-crystal structure of the mixed metal butterfly cluster (μ 4 -η 2 -RC 2 R)Co 2 Rh 2 (CO) 8 (μ-CO) 2 , alkyne = C 6 F 5 , Ph. In addition, the X-ray single-crystal structure 24 of (μ 4 -η 2 -PhC 2 Ph)Co 3 Rh(CO) 8 (μ-CO) 2 and recently the structure of (μ-dmad) 3 CoRh 3 (CO) 9 , dmad = (CH 3 O)COCCCO(OCH 3 ), were reported …”