87900-84-3Relevant academic research and scientific papers
Synthesis and characterization of tungsten alkenyl-carbyne complexes [(dppe)(CO)2LW≡CCH=CCH2(CH2) nCH2CH2][BF4] (L = CO, MeCN, PMe3) and [(dppe)(CO)2XW≡CCH=CCH2(CH2]
Zhang, Lei,Gamasa, M. Pilar,Gimeno, José,Carbajo, Rodrigo J.,López-Ortiz, Fernando,Lanfranchi, Maurizio,Tiripicchio, Antonio
, p. 4274 - 4284 (2008/10/08)
Alkenyl-vinylidene complexes mer-[(dppe)(CO)3W=C=CHC=CH(CH2)nCH 2CH2] (dppe = 1,2-bis(diphenylphosphino)ethane; n = 1 (1a), n = 3 (1c), n = 4 (1d)) have been prepared by reaction of the complex fac-[(dppe)(CO)3W(Me2CO)] with 1-ethynylcyclopentanol, 1-ethynylcycloheptanol, and 1-ethynylcyclooctanol. Protonation at the Cδ of the alkenyl-vinylidene moiety with HBF4·OEt2 in diethyl ether or THF leads to the formation of cationic alkenyl-carbyne complexes mer-[(dppe)(CO)3W=CCH=CCH2(CH2) nCH2CH2][BF4] (n = 1 (2a), n = 3 (2c), n = 4 (2d)). When the protonation is carried out in CH2Cl2, isomeric carbyne complexes mer-[(dppe)(CO)3W≡CCH2C=CH(CH2) nCH2CH2][BF4] (2a′, 2c′, 2d′) are also generated. The alkenyl-carbyne complexes undergo carbonyl substitution by donor ligands to give dicarbonyl derivatives of the following types: (a) cationic complexes trans-[(dppe)(CO)2LW≡ CCH=CCH2(CH2)nCH2CH 2][BF4] (L = CH3CN, n = 1 (3a), n = 4 (3d); L = PMe3, n = 1 (4a), n = 4 (4d)) and (b) neutral complexes trans-[(dppe)(CO)2XW≡CCH=CCH2(CH2) nCH2CH2] (X = Cl, n = 1 (5a), n = 2 (5b), n = 3 (5c), n = 4 (5d); X = Br, n = 1 (6a), n = 4 (6d); X = I, n = 1 (7a), n = 3 (7c), n = 4 (7d)). The structure of complex 5a was determined by X-ray diffraction methods. The W atom displays a distorted octahedral coordination with the Cl atom [W-Cl = 2.540(1) A?] trans to the alkenyl-carbyne group [W≡C = 1.830(3) A?]. IR and 1H, 31P, 13C, and 183W NMR data are reported. The sequence for the trans influence in the order alkenyl-carbyne > alkenyl-vinylidene > CO could be found from the corresponding 1J(31P-183W) values. The low values for the alkenyl-carbyne groups are among the lowest ever reported, indicating a high trans influence of the carbyne group. 183W chemical shifts of compounds 1a-7a were obtained through two-dimensional indirect 31P, 183W recording techniques. A down field shifting of 183W resonances with decreasing π-acceptor ability of the ligands in complexes 2a-7a was observed.
Carbonyl Monoolefin Derivatives of the Group VI Transition Metals. III. Preparation and Reactivity of Tricarbonyl Chelate Phosphane Olefin Derivatives
Schenk, Wolfdieter A.,Mueller, Helmut
, p. 3618 - 3630 (2007/10/02)
Monoolefin complexes M(CO)3(R2PC2H4PR2)(ol) (M = Cr, Mo, W; R = CH3, C6H5; ol = maleic anhydride, dimethyl fumarate, dimethyl maleate, methyl acrylate, ethylene, styrene, norbornene) are obtained photochemically from the tetracarbonyl chelate phosphane derivatives.Facial complexes are formed primarily, some of which rearrange intramolecularly to the meridional isomers.The substitution of the olefin proceeds via a dissociative mechanism, the meridional isomers rearrange back to the facial ones prior to the rupture of the metal-olefin bond.
