Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 77. Reactions of iron–molybdenum compounds with alkynes; crystal structures of [MoFe{µ-C(C₆H₄Me-4)C(CHMe)CH₂C(Me)C(Me)}(CO)₄(η-C₅H₅)], [MoFe{µ-C(C₆H₄Me-4)C(CHMe)CH₂}(CO)₅(η-C₅H₅)], and [MoFe{µ-C(C₆H₄Me-4)C(CH₂PMe₃)CHMe}(CO)₅(η-C₅

Chemistry of Highly Electrophilic Binuclear Cations. 5. Addition and C−C and C−P Coupling Processes in the Reactions of 1-Alkynes with the Dimolybdenum Radicals [Mo2(η5-C5H5)2(μ-CO)2(CO)2(μ-L2)][B{3,5-C6H3(CF3)2}4] (L2 = Ph2PCH2PPh2 or Me2PCH2PMe2)

“…The intermediate C would next experience C−C coupling between the alkyne and the hydroxycarbyne group, giving finally compounds 4 and 6 . This kind of C−C coupling with alkynes has been reported before for arylcarbyne-bridged complexes, for example, [MFeCp{μ-η 2 :η 3 -C(p-tol)CRCR}(CO) 5 ] from [MFeCp{μ-C(p-tol)}(CO) 6 ] and RCCR (M = Mo, , W). In our case, we note that the C−C coupling is regiospecific except for the combination involving the diphosphine (dmpm) and alkyne (HCCCO 2 Me) having smaller steric requirements, in which case two isomers ( 6c and 7 ) are obtained.…”

Hydrocarbyl Ligand Transformations on Heterobimetallic Complexes

“…In some cases, the organic ligands are similar to those found in complexes 149 . This is the case when diphenylacetylene reacts with complex 138a to give 109f , Scheme . , Hex-3-yne gives the similar species 109c , but a byproduct of the reaction, 150 , contains an alkyne−CO−carbyne linkage and can be considered to be a ferracyclopentenone complex, that is, an isomer of 110c (see Scheme ). , Terminal alkynes afford ferracyclopentenone species of type 110 with alkylidyne−alkyne−CO rather than alkyne−CO−alkylidyne linkages. Both classes of complexes ( 109 , molybdenacyclobutadienyl, or ferracyclopentenone species 110 ) are obtained with ethyne or but-1-yne.…”

“…Products 151 contain molybdenum-substituted “trimethylenemethane” moieties and exist as a 3:2 mixture of isomers in solution. There are no Fe−Mo bonds in these species as attested by the X-ray crystal structure of one of the isomers (Fe···Mo = 4.027 Å). , Isomeric mixture 151 undergoes a formal CO insertion to give a new 1:1 mixture of the molybdenum acyl trimethylenemethane products 152 shown in Scheme …”

“…This fragment is derived from the tolylmethylidyne group, a 2-butyne molecule, and a CO ligand. A metal−metal bond is present. , All these spectacular transformations and couplings are summarized in the very busy Scheme .…”