The reaction of [(CO)5WC(Ph)H] with Me2NC⋮CNMe2 affords two complexes: the
binuclear complex [(CO)5WC(NMe2)(Me2N)CW(CO)5] (2) and the insertion product
[(CO)5WC(NMe2)C(NMe2)C(Ph)H] (3). Sequential reaction of the (dimethylamino)ethynylcarbene complex [(CO)5WC(NMe2)C⋮CH] (4a) with nBuLi, W(CO)6, and F3CSO3Me yields the new ethynediyl-bridged binuclear alkoxycarbene−aminocarbene complex
[(CO)5WC(NMe2)C⋮C(MeO)CW(CO)5] (5). Treatment of 4a and of [(CO)5CrC(NMe2)C⋮CH] (4b) with nBuLi and iodine gives the new iodine-substituted complexes [(CO)5MC(NMe2)C⋮CI] (M = W (6a), M = Cr (6b)). By Pd-catalyzed coupling of 6a,b with the
C-stannylated ethynylcarbene complexes [(CO)5MC(NMe2)C⋮CSn(nBu)3] (7a,b) the
butadiynediyl-bridged bis(carbene) complexes [(CO)5MC(NMe2)(C⋮C)2(Me2N)CM(CO)5]
(8a,b) are obtained. Analogously, from [(CO)5WC(NMe2)(C⋮C)
x
H] (x = 2, 3) and nBuLi/I2
amino(iodobutadiynyl)carbene and amino(iodohexatriynyl)carbene complexes [(CO)5WC(NMe2)(C⋮C)
x
I] (x = 2 (10), 3 (14)) are obtained. Pd-catalyzed coupling with the
corresponding C-stannylated alkynylcarbene complexes finally affords the binuclear C10(NMe2)2- and C14(NMe2)2-bridged complexes [(CO)5WC(NMe2)(C⋮C)
x
(Me2N)CW(CO)5] (x
= 4 (12), 6 (16)). All alkynediyl-bridged bis(carbene) complexes are stable at room
temperature. The spectroscopic data of 5 indicate that it is best described as a hybrid of a
dipolar allenyl-type compound and an alkynylcarbene complex. In contrast, the C⋮C units
in the binuclear complexes 8a,b, 12, and 16 are essentially localized.
Die Synthese von Cyclopropen‐Komplexen nicht über Ligandenverdrängungsreaktionen, sondern durch Verknüpfung eines Carbenliganden mit einem Alkin am Metall gelang erstmals für 1, R = H, Me. Bereits oberhalb von ‐ 40°C lagert sich 1 stereoselektiv in den Vinylcarben‐Komplex 2 um.
from 1.69 to 4.51). Full-matrix least-squares refinement of positional and anisotropic thermal parameters of all non-H atoms and an overall isotropic thermal parameter for H atoms converged at a final R value: 0.043 wR = 0.051; w -' = d ( F ) for 5267 unique reflections with
1992 organo-tungsten compounds organo-tungsten compounds S 5700 28 -241 Kinetic and Mechanistic Investigations on Reactions of Transition-Metal Complexes. Part 26. Kinetic Investigations of the Cyclopropanation of Olefins by Benzylidene(pentacarbonyl)tungsten Complexes. -The transfer rates of the benzylidene ligand from (I) to the double bond of the olefins (II) and (V) giving cyclopropanes in different solvents are determined. The influence of the solvent on the reaction rate is small. Activation parameters are given. The cis/trans ratio is discussed in dependence of olefin concentration and temperature. -(FISCHER, H.; MAUZ, E.; JAEGER, M.; FISCHER, R.; J.
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