Showing papers by "Richard D. Adams published in 1994"

The catalytic cyclooligomerization of thietane by trirhenium cluster complexes. a new route to polythiaether macrocycles

Abstract: The trirhenium complex Re[sub 3](CO)[sub 10] [[mu]-SCH[sub 2]CH[sub 2]]([mu]-H)[sub 3] (1) reacts with dimethyl sulfide by a ring opening addition to the bridging thietane ligand to yield the zwitterionic complex Re[sub 3](CO)[sub 10][[mu]-SCH[sub 2]CH[sub 2]CH[sub 2]SMe[sub 2]]([mu]-H)[sub 3] (2) in 48% yield that contains a sulfonium-substituted thiolate ligand bridging an edge of the cluster. The structure of 2 was established by a single-crystal X-ray diffraction analysis. In this report, the results of our studies of the reactions of 1 with the thiaethers Me[sub 2]S and thietane, itself, are described. It is demonstrated that these thiaethers also produce ring opening of the bridging thietane ligand in 1, but in the case of thietane, a series of ring-opening coupling reactions occurs that is concluded by cyclization processes that yield polythiaether macrocycles. Indeed, the ring-opening cyclization can be performed catalytically under suitable conditions to yield the macrocycles in a free state in substantial amounts. 13 refs., 2 figs., 6 tabs.

Coupling of Alkynes to Carbon Monoxide at a Dimanganese Center. A New Route to Carboxylate-Functionalized Pyrans

Abstract: Metal-mediated coupling reactions between alkynes and CO have led to a wide variety of new organic ligands and new organic molecules. Recent studies of the reactions of alkynes with dinuclear manganese carbonyl complexes have revealed a tendency for coupling of the alkynes to one or more of the CO ligands. A special feature of these reactions is the coordination of the oxygen atom of the CO group of the metal atoms. We have now found that the reaction of EtO[sub 2]CC[triple bond]CCO[sub 2]Et with Mn[sub 2](CO)[sub 9](NCMe) at 25[degree]C for 20 h produces the new compound Mn[sub 2](CO)[sub 8][EtO[sub 2]CC=C(CO[sub 2]Et)C=O], 1, in a 22% diffraction analysis, and an ORTEP diagram of its molecular structure is shown. The molecule contains a EtO[sub 2]CC=C(CO[sub 2]Et)C=O ligand formed by the coupling of the alkyne to the carbon atom of a CO ligand. Most importantly, the EtO[sub 2]CC=C(CO[sub 2]Et)C=O ligand has been inserted into the manganese-manganese bond. The oxygen atom of the CO group and one carbon atom of the EtO[sub 2]CC=CCO[sub 2]Et grouping are coordinated to the metal atom Mn(1), resulting in the formation of a five-membered metallacyclic ring. The carbon atom of the CO group and the carbonyl oxygen O(4) ofmore » one of the carboxylate groups are coordinated to Mn(2) to form a second five-membered metallacyclic ring. 15 refs., 2 figs.« less

The synthesis of platinum and palladium cluster compounds with isocyanide or functionalised phosphine ligands. Crystal structures of [Pt5(CO)(μ-CO)5{Ph2PCH2C(O)Ph}4] and [Pt5(μ-CNC6H3Me2-2,6)3(CNC6H3Me2-2,6)5Ph2PCH2C(O)Ph}2]

Abstract: The reaction of the ketophosphine ligand Ph2PCH2C(O)Ph (P∼O) with [PtCl2(NCMe)2] and carbon monoxide in THF in the presence of an excess of zinc afforded the 70 electron pentanuclear cluster [Pt5(CO)(μ-CO)5(P∼O)4] (1). Reaction of the palladium(0) complex [Pd2(dba)3] CHCl3 (dba = dibenzylideneacetone) with Ph2PCH2C(O)R [R = Ph or C5H4Fe(C5H5)] under SO2 led to the pentapalladium cluster compounds [Pd5(μ3-SO2)2 (μ-SO2)2 {Ph2PCH2C(O)R}5] (2a,R = Ph;2b,R = C5H4Fe(C5H5)), Cluster (1) reacts with 2,6-xylyl isocyanide, CNC6H3Me2-2,6 to give a red cluster of formula [Pt5(μ-CNC6H3Me2-2, 6)3 (CNC6H3Me2-2, 6)5 (P∼O)2] (3) and a green complex (4). The corresponding complexes (6) and (7) were also obtained by using PPh3 instead of P∼O. Clusters (2a) and (2b) react with [NEt3Bz] Cl to give[NEt3Bz][Pd3(μ-SO2)2 (μ-Cl){Ph2PCH2C(O)R}3](8a,R = Ph;8b,R = C5H4Fe(C5H5)). The molecular structures of (1) and (3) were determined by single-crystal X-ray diffraction analyses.

The synthesis and structural analysis of the new high nuclearity platinum-ruthenium cluster complex Pt2Ru8(CO)18(μ3−EtC2Et)2(μ4−EtC2Et) containing three alkyne ligands

Abstract: The ten metal cluster complex Pt2Ru8(CO)23(µ3−H)2, 1 was found to react with EtC2Et to form a new ten metal tris-alkyne complex Pt2Ru8(CO)18(µ3−EtC2Et)2 (µ4−EtC2Et),2 in 35% yield. Complex 2 was characterized by IR,1H NMR , and single crystalx-ray diffraction analyses. The cluster can be viewed as a dodecahedron of eight metal atoms capped with two ruthenium carbonyl groups, two triply bridging EtC2Et ligands and one quadruply bridging EtC2Et ligand. Application of the standard electron counting procedures indicate that this is an unusual complex in which the 18 electron rule applies and the polyhedral skeletal electron pair theory does not. Crystal Data for 2 2.0.5 CH2CI2: space group = P21,a = 12.759(2) A,b=18.438(2)A,c = 20.197(3) A,β = 91.59(1)°, Z. = 4, 6394 reflections,R = 0.037.

A new platinum-osmium alkyne complex from the reaction of Pt2Os4(CO)18 with PhC ≡ CPh: The synthesis, characterization, and crystal structure of Pt2Os4(CO)8 (μ3-PhC2Ph)3(μ4-PhC2Ph)

Abstract: The new platinum-osmium alkyne cluster complex Pt2Os4(CO)8(μ3-PhC2Ph)3 (μ4-PhC2Ph),2, was obtained from the reaction of Pt2Os4(CO)18,1b, with PhC2Ph and was characterized by IR.1H NMR and single-crystal X-ray diffraction analyses. The cluster of compound2 consists of an osmium capped Pt2Os3 square pyramid. It aLso contains three triply bridging and one quadruply bridging diphenylacetylene ligands. Crystal data for2: space group PI,a = 12.530(2) A,b = 21.565(4) A,c = 11.284(2) A,α = 100.31(2),β = 111.89(1),β = 76.78(2),Z = 2, 3879 reflections,R = 0.032.