Phosphorus ylides as hard donor ligands: synthesis and characterization of MCl4(ylide-O)(THF) (M = Ti, Zr, Hf; ylide = (acetylmethylene)triphenylphosphorane, (benzoylmethylene)triphenylphosphorane). Molecular structure of trans-((acetylmethylene)triphenylphosphorane-O)(tetrahydrofuran)tetrachlorotitanium-(IV)-tetrahydrofuran

Abstract

262ChemInform Abstract The title compounds (IV) are obtained as shown and characterized by NMR and IR spectroscopy. Their structure is confirmed by X-ray analysis of the Ti title complex (IVa) (M: Ti; space group P21/n, Z=4).

Early transition-metal complexes of ?-keto-stabilized phosphorus ylides

“…5 A decreasing carbonyl streching frequency in the IR spectrum of the complex, resulting from major contributions from the resonance structure Ph 3 P -CH=C(Ph)-O À , confirms that the ligand is bound through the carbonyl oxygen ( Table 2).…”

“…This is in accordance with the general trend of the coupling constants: free ylide b O-coordinated ylide b ylide hydrohalide salt (phosphonium salt) b C-coordinated ylide. 5 We often found that the complexes of the ylides generated with early transition metals are very unstable and not isolable. These intermediates undergo consecutive reactions in which one NMe 2 group is transferred from the starting metal complex to the ylide.…”

“…Whereas complexes of a-keto-stabilized phosphorus ylides with late transition-metal ions are thoroughly investigated, there are only a few examples of such complexes with early transition metals. 5,6 We describe here an investigation into the complexation behaviour of the phosphorus ylides Ph 3 P=CHC(O)R (R = Ph, Me) toward early transition-metal ions.…”

X-ray and Spectroscopy Studies of Mercury (II) and Silver (I) Complexes of α-Ketostabilized Phosphorus Ylides

“…[6][7][8][9][10][11][12][13][14][15][16][17][18][19] They are versatile ligands for catalysts in a very small number of catalytic reactions such as, for example, the hydrogenation of olefins 20 and the cyclotrimerization 21 and polymerization of acetylenes, 22 but the most important application is in the industrially used SHOP process. 23 The α-keto-stabilized phosphorus ylides are distinguishable from no stabilized ylides, since they can be easily handled due to an additional stabilization from delocalization of the negative charge.…”

Synthesis, characterization, and spectroscopic studies of palladium(II) and silver(I) complexes of 4-methoxybenzoylmethylenetriphenylphosphorane and 4-fluorobenzoylmethylenetriphenylphosphorane

“…In the compounds reported to date, the chemical behavior of the a-ketostabilized phosphorus ylides has been clearly dominated by the C-coordinated form [7][8][9][10][11], and very few examples of O-coordinated ylides are known [6,[12][13][14][15]. Some of these examples contain the ylide O-coordinated to a hard, very exophilic metal center, as Sn(IV) [12] or group 4 metals in high oxidation number [13].…”