Preparation of Four-and Five-Membered Diruthenacycles and an Unusual Double Insertion of Carbon Monoxide. Crystal and Molecular Structures of Ru2(Me2PCH2PMe2)2(CO)3,[μ-C2(CO2Me)2][C(O)C(O)C2(CO2Me)2] and Ru2(Me2PCH2PMe2)2(CO)4[μ-C(O)C2(CO2Me)2]

Kimberly A. Johnson, Wayne L Gladfelter

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Abstract

The reaction of Ru2(dmpm)2(CO)5, where dmpm = bis(dimethylphosphino)methane, with dimethyl acetylenedicarboxylate (DMAD) resulted in the formation of three isolable products, each of which can be prepared in ~80% yield by varying the reaction conditions. In very concentrated solutions at room temperature, the presence of excess DMAD led to Ru2(dmpm)2(CO)3[μ-C2(CO2Me)2][C(O)C(O)C2(CO2Me)2] in 81% yield. The X-ray crystal structure [P212121 (No. 19) space group, a= 13.932 (5) Å, b = 14.360 (3) Å, c = 17.854 (3) Å, V = 3572 (3) Å3, Z = 4] established that one alkyne was bound as a cis-dimetalated alkene, while the other was incorporated into a five-membered metallacycle. This metallacycle appeared to have formed by the insertion of two carbon monoxide ligands into a metal-alkyne bond. When the reaction was conducted at room temperature in dilute solution, the product, Ru2(dmpm)2(CO)4[μ-C(O)C2(CO2Me)2] contained only 1 equiv of DMAD. X-ray crystallography [P21/n (No. 14) space group, a = 10.845 (5) Å, b = 27.82 (1) Å, c = 10.447 (5) Å, β = 109.90 (4)°, V = 2964 (5) Å3, Z = 4] showed the alkyne had again been incorporated into a five-membered metallacycle, in a 1,2-diruthenacyclopentenone arrangement When the reaction of Ru2(dmpm)2(CO)5 with DMAD was conducted at elevated temperatures or when Ru2(dmpm)2(CO)4[μ-C(O)C2(CO2Me)2] was heated, loss of one CO ligand to form a 1,2-diruthenacyclobutene resulted. Methyl propiolate was also found to react slowly (25–30 h at room temperature) with Ru2(dmpm)2(CO)5 yielding a product that was analogous to the 1,2-diruthenacyclobutene described for DMAD.

Original languageEnglish (US)
Pages (from-to)2534-2542
Number of pages9
JournalOrganometallics
Volume11
Issue number7
DOIs
StatePublished - Jul 1 1992

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