Monomeric Bis(η2-alkyne)copper(I) and -silver(I) Halides, Pseudohalides, and Arenethiolates

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Abstract
The synthesis and characterization of the complexes [(η5-C5H4SiMe3)2Ti(C⋮CSiMe3)2]MX (M = Cu, X = OTf (2), SC6H5 (4), SC6H4NMe2-2 (5), SC6H4CH2NMe2-2 (6), S-1-C10H6NMe2-8 (7), Cl (8), (N⋮CMe)PF6 (9); M = Ag, X = OTf (3)) are described. These complexes contain monomeric MX entities, which are η2-bonded by both alkyne functionalities of the organometallic bis(alkyne) ligand [(η5-C5H4SiMe3)2Ti(C⋮CSiMe3)2] (1). The reactions of 2 with the Lewis bases N⋮CPh and N⋮CC(H)C(H)C⋮N afford the cationic complexes {[(η5-C5H4SiMe3)2Ti(C⋮CSiMe3)2]Cu(N⋮CPh)}OTf (10) and {[(η5-C5H4SiMe3)2Ti(C⋮CSiMe3)2]Cu}2(N⋮CC(H)C(H)C⋮N)(OTf)2 (11), respectively. The X-ray structures of 2, 3, and 6 have been determined. Crystals of 2 are monoclinic, space group P21/c, with a = 12.8547(7) Å, b = 21.340(2) Å, c = 18.279(1) Å, β = 133.623(5)°, V = 3629.7(5) Å3, Z = 4, and final R = 0.047 for 5531 reflections with I ≥ 2.5σ(I) and 400 variables. The silver triflate complex 3 is isostructural, but not isomorphous, with the corresponding copper complex 2, and crystals of 3 are monoclinic, space group P21/c, with a = 13.384(3) Å, b = 24.55(1) Å, c = 13.506(3) Å, β = 119.21(2)°, V = 3873(2) Å3, Z = 4, and final R = 0.038 for 3578 reflections with F ≥ 4σ(F) and 403 variables. Crystals of the copper arenethiolate complex 6 are triclinic, space group P1̄, with a = 11.277(3) Å, b = 12.991(6) Å, c = 15.390(6) Å, α = 65.17(4)°, β = 78.91(3)°, γ = 84.78(3)°, V = 2008(2) Å3, Z = 2, and final R = 0.079 for 6022 reflections and 388 variables. Complexes 2−11 all contain a monomeric bis(η2-alkyne)M(η1-X) unit (M = Cu, Ag) in which the group 11 metal atom is trigonally coordinated by the chelating bis(η2-alkyne) entity Ti(C⋮CSiMe3)2 and an η1-bonded monoanionic ligand X. The copper arenethiolate complexes 4−7 are fluxional in solution.