Ruthenium complexes tricyclohexylphosphine

Second-generation ruthenium-carbene complex, (tricyclohexylphosphine-[l,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene][benzylidene]ruthenium (IV) dichloride),4e was purchased from Strem Chemicals. 

Ruthenium complexes have been described that are active both in the ROMP reaction and in a subsequent hydrogenation step (30). These catalysts have the pyrimidin moiety incorporated, for example, (l,3-diisopropyltetrahydropyrimidin-2-ylidene) (ethoxy-methylene) (tricyclohexylphosphine) ruthenium dichloride. 

Ring D (see Scheme 15) has been successfully appended to the tricyclic core by an olefin metathesis reaction (147). Treatment of 177, prepared largely by the method described in Scheme 11, with the ruthenium complex 178 (Cy3P = tricyclohexylphosphine) resulted in the ABCD ring system of the manzamines. 

OHj, Water, chromium and vanadium complexes, 27 307, 309 iridium complex, 26 123, 28 58 ruthenium complex, 26 254-256 OlPjRhCjjHgg, Rhodium(I), carbonyliodo-bis(tricyclohexylphosphine)-, 27 292 OLiNC,jH22, Lithium, (diethyl ether)(8-(dimethylamino)-l-naphthyll-, 26 154 OLUC21H25, Lutetium, bis(ii -Cyclopenta-dienyl)(tetrahydrofuran)-p-tolyl-,... 

Chaudret and coworkers synthesized an ortho-ruthenated acetophenone complex (26) having axial tricyclohexylphosphine ligands. Complex 26 showed almost no catalytic activity, and on the basis of this observation and the activity of 22, they proposed that the binding of the CO Hgand to the ruthenium suppresses the catalytic activity of the ruthenium complex. Fogg and coworkers prepared ortho-ruthenated benzophenone complex 27, which showed only low catalytic activity and was proposed to be a catalytic sink in the alkylation of aromatic ketones. Weber and coworkers synthesized a unique zero-valent ruthenium complex (23), which was effective for the alkylation of aromatic ketones. Subsequently, Whittlesey and coworkers synthesized complex 25, which did not catalyze the hydroarylation. However, the authors stated it was highly Hkely that alternative isomers of 25 could be involved in the catalytic pathways. Further hints toward this end came with the characterization of the two N,0-coordinated acetylpyrrolyl complexes 24 and 28. Complex 24 was found to be an active catalyst of the reaction but was shown to isomerize to its inactive isomer 28 at 80 °C. 

Once the NHC was introduced onto the ruthenium center, the addition of pyridine (10 equiv.) led to the 16-electron, monopyridine indenylidene complexes 54a-f (Scheme 14.24) [55, 56, 65, 66]. Interestingly, from a synthetic point of view, this preparation can also be achieved starting from (triphenylphos-phine)(indenylidene)ruthenium complexes, thereby avoiding the use of the costly and sensitive tricyclohexylphosphine [50,66]. The monopyridine complexes bearing mesityl substituents on the nitrogens were not very active at room temperature for the RCM of dienes and enynes, nor in the CM of methyl acrylate [66]. However, the controlled ROMP of norbornene-type monomers was allowed [65]. In contrast, the indenylidene complexes 54b and 54f, which bear 2,6-diisopropylphenyl substituents on the NHC and either a pyridine or 3-bromopyridine ligand, were... 

Experimental Procedure 3.1.3. Preparation of a Ruthenium Carbene Complex from a Diazoalkane Dichloro-bis(tricyclohexylphosphine)benzylideneruthenium... 

The synthesis of a ruthenium catalyst in a one step procedure is shown in Figure 1.8. A dimer complex of cymene, i.e., 4-iso-propyltoluene) and RuC is reacted under inert atmosphere with tricyclohexylphosphine and 3,3-diphenylcyclopropene in benzene... 

Tricyclohexylphosphine Complexes of Ruthenium, Rhodium, and Iridium and Their Reactivity Toward Gas Molecules... 

Tricyclohexylphosphine was obtained from Strem Chemicals. Ruthenium, rhodium, and iridium trichlorides were obtained as trihydrates from Johnson, Matthey Limited. Iridium tetrachloride was obtained from Platinum Chemicals. The precursor complexes [RhCl(COD)]2 (57), [RhCl(COT)2]2 (58), [RhCl(C2H4)2]2 (59), [IrCl(COD)]2 (14), and [HIrCl2-(COD)]2 (31) were made according to the literature procedures. 

The activity of the ruthenium alkylidene complex can be greatly increased by exchanging triphenylphosphine ligands for the more electron-donating bulky tricyclohexylphosphine ligands a complex with the latter ligands is active for the polymerisation of only slightly strained cyclopentene [93,94]. 

H5N2C, Hydrazine, methyl-, ruthenium(II), complexes, 26 72 H,B , Diborane(6), 27 215 HftMoPiCyHw), Molybdenum(IV), hexahy-dridotris(tricyclohexylphosphine)-, 27 13... 

A convenient route to a synthetically useful ruthenium polyhydride complex is the reaetion of Ru (COD) (COT) with 2 equiv. of tricyclohexylphosphine under hydrogen ... 

A new preparation of catalytically active ruthenium-carbene complexes can avoid difficulty by using accessible starting materials such as (PhjPjjRuClj and carbene precursors (e.g., diazoalkanes and diphenylcyclopropenes). It involves reduction of RuCl3 3H20 in THF Mg/ClCHjCHjCl in the presence of tricyclohexylphosphine under hydrogen at 60-85° which is followed by cooling to -40° and addition of a 1-alkyne along with a small amount of water. 

Scheme 1. Ruthenium-p-cymene complexes bearing a tricyclohexylphosphine...

Scheme 2. Homobimetallic ruthenium-arene complexes bearing a tricyclohexylphosphine ligand...

After having observed that the most active ruthenium-based catalyst systems for olefin metathesis also displayed a high efficiency in atom transfer radical polymerisation, we then became interested in comparing the role of the catalyst in those two different reaction pathways. Ruthenium alkylidene complexes 4-6 are unsaturated 16-electron species which formally allow carbon-halogen bond activation to form a 17-electron ruthenium(III) intermediate. Our preliminary results indicate that polymerisations occur through a pathway in which both tricyclohexylphosphine and/or imidazolin-2-ylidene ligands remain bound to the metal centre. 

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