154593-29-0Relevant academic research and scientific papers
Molecular solid-gas organometallic chemistry. Catalytic and stoichiometric iridium-assisted C-C bond-forming reactions involving ethyne and ethene
Bianchini, Claudio,Graziani, Mauro,Kaspar, Jan,Meli, Andrea,Vizza, Francesco
, p. 1165 - 1173 (1994)
Treatment of crystals of the (η2-ethene)dihydride complex [(triphos)Ir(H)2(C2H4)]BPh4 (1; triphos = MeC(CH2PPh2)3) with ethyne (4 atm) at 70°C for 3 h results in evolution of ethene and but-2-ene and formation of five different organometallic products, namely the η4-benzene complex [(triphos)Ir(η4-C6H6)]BPh4 (2), the η4-buta-1,3-diene complex [(triphos)Ir(η4-C4H6)]BPh4 (3), the η4-cyclohexa-1,3-diene complex [(triphos)Ir(η4-C6H8)]BPh4 (4), and the crotyl hydride isomers [(triphos)Ir(H)(η3-MeC3H4)]BPh4 (5-anti and 5-syn) in a kinetic product ratio of 35:5:23:28:9. At 100°C, the solid-gas reaction produces catalytic amounts of benzene, the catalyst precursor being the η4-benzene complex 2. Temperature-programmed reactions carried out in a flow reactor and the use of isolated complexes in independent solid-gas reactions permit mechanistic conclusions which account for the varied organic and organometallic products. The ethene ligand in 1 is an essential ingredient for both cyclotrimerization and cooligomerization reactions of ethyne, which are traversed by η3-crotyl complexes. Conversely, the ethene ligand is a competitive inhibitor for the reductive dimerization of ethyne to buta-1,3-diene, for which the two hydride ligands are mandatory. Comparison with fluid solution-phase systems provides evidence for the control exerted by the constraining environment of the crystal lattice on the solid-gas reactions.
