Ylide ligands

Complexes containing the ylide ligand can be also obtained by reaction of the yellow solution of ylides (prepared by addition of butyllithium to tetrahydrofurane or diethylether solutions of the phosphonium salt) with [AulCfiFs) (tht)]. The weak ligand tht is replaced and the ylide complex is obtained (Equation 3.5) [70]. 

Romeo, L, Bardaji, M., Concepcion Gimeno, M. and Lagrma, M. (2000) Gold(I) complexes containing the cationic ylide ligand bis (methyldiphenylphosphonio) methylide. Polyhedron, 19(15),... 

The bis-ylide ligands [R2P(CH2)2] can easily be prepared by treatment of the phosphonium salts [R2PMe2] (R = Me, Ph) with strong deprotonating reagents such as lithium derivatives, NaNH2, or non stabilized ylides R3P=CH2. However, Au Ag, and Cu complexes (99) were prepared by reaction of ClMPMe3 (M = Ag, Au) or CuCl with excess of R3P=CH2 [202, 203] (Scheme 30). 

Iminio-phosphonio dications have been obtained by N- and F-methylation of (imidazolylphenyl)diphenylphosphine. These dications are suitable precursors for C,C-chelating ligands. Deprotonation of the N-heterocycle leads to an NHC carbene which can be coordinated to a suitable metal center like Pd The subsequent deprotonation of the phosphonio moiety gave the complex with a bidentate chelating coordinated NHC-ylide ligand [207, 208]. 

Figure 2.75 Mixed valence complexes with ylide ligands.

Chloro platinum ylide complexes will undergo replacement of Cl for acetone in the presence of NaBPlu.437 The ylide complexes (35) undergo oxidative addition at platinum(II) by Mel, and substitution of pyridine by CO to give the carbonyl complex. The ylide ligand is not displaced.438... 

Me) isomerized in the presence of NEt3 to form the cation [Cp-(I)RhCH2PMe2CH2CH2PMe2]+, which contains an a-C,tu-P-bonded cyclic ylide ligand (98). 

Complex 40 is an iron complex with a phosphorus ylide ligand (-CH2PR3) (Scheme 3). It reacts with TMSOTf to give 42 which can be converted into an isolable complex 43 by the addition of -Bu4NBr.37 The reaction sequence is shown in Scheme 3. Two points should be noted in this reaction (i) an OMe anion is able to be abstracted by... 

TMSOTf even in a cationic complex, and (ii) a cationic phosphorus ylide ligand can migrate to a cationic phosphenium ligand. The reaction has been confirmed to take place through intramolecular migration. 

The itnido complexes [M(NBu-t)2(CH=PPh3)Cl] (M = Mo, W) react with 245 to afford complexes 246 resulting after a C—O bond cleavage and the migration of the ylide ligand to the carbonyl carbon atom. [Os3H2(CO)io] reacts with maleic anhydride... 

Methylene insertion into the Au—S bonds of the heterobimetallic complex 501 results in the formation of the larger ylide ligands in 502 (280). 

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