Acetone complexes

Reaction of the cyclopentadienyl rhodium and iridium tris(acetone) complexes with indole leads to the species 118 (M = Rh, Ir) [77JCS(D)1654 79JCS(D)1531]. None of these compounds deprotonates easily in acetone, but the iridium complex loses a proton in reaction with bases (Na2C03 in water, r-BuOK in acetone) to form the ri -indolyl complex 119. This reaction is easily reversed in the presence of small amounts of trifluoroacetic acid. 

The acetone complex [IrH2(Me2CO)(Hpz)(PPh3)2]BF4 reacts with potassium hydroxide to give 128 [94JOM(466)249 94JOM(467) 151]. The pyrazolate bridge... 

Figure 3 shows 13c MAS spectra of acetone-2-13c on various materials. Two isotropic peaks at 231 and 227 ppm were observed for acetone on ZnCl2 powder, and appreciable chemical shift anisotropy was reflected in the sideband patterns at 193 K. The 231 ppm peak was in complete agreement with the shift observed for acetone diffused into ZnY zeolite. A much greater shift, 245 ppm, was observed on AICI3 powder. For comparison, acetone has chemical shifts of 205 ppm in CDCI3 solution, 244 ppm in concentrated H2SO4 and 249 ppm in superacid solutions. The resonance structures 5 for acetone on metal halide salts underscore the similarity of the acetone complex to carbenium ions. The relative contributions of the two canonical forms rationalizes the dependence of the observed isotropic 13c shift on the Lewis acidity of the metal halide. 

The Rh(COD)(PPh3) (acetone)+ complex is a useful precursor for the mixed L L2 cation complexes (140a). 

Appendix, we present tables summarizing the reactions that have been carried out with each metal vapor. For the sake of completeness, we have included a few types of reactions in which the products are not organometallic e.g., the formation of metal-phosphine and metal-acetyl-acetone complexes. Our review covers the literature up to February 1976 with selected references added in proof in December 1976. 

Similar acetone complexes can also be prepared from the PPh3 containing tetrafluoroborate complexes. 

Fig. 7. Energy-minimized structures of acetone and mesityl oxide adsorption complexes on a cluster model of HZSM-5 using DFT calculation. Note that in the case of the acetone complex, the proton remains bonded to the bridging oxygen, while in the case of the mesityl oxide complex, the proton is more fully transferred to the ketone. (Reprinted with permission from Haw et al. (7). Copyright 1996 American Chemical Society.)...

Acetone complexes are also prepared by the trans activation of the ammine ligands in [Osn(NH3)5(C-Mepy)]2 + to form (r[Pg.285]

Epoxydioxepane 124 was converted with a LiCN-acetone complex (prepared from acetone cyanohydrine and methyllithium CAUTION ) into /3-hydroxy nitrile 127 <2004TL7201>, and epoxydioxepane 128 with lithium amide into hydroxydioxepin 128 (Scheme 32) <2004RJOC1830>. 

Unsymmetrical vicinal diols can be prepared from a three-component reaction of aldehydes, CO, and aminotroponiminate-ligated titanium dialkyl complexes. Solutions of Me2TiL2 (L = ALN -dimelhylaminoLroponiminale) react rapidly with CO at room temperature. Double methyl migration to CO produces an q2-acetone complex which inserts the aldehyde to afford a titana-dioxolane and releases the unsymmetrical diol upon hydrolysis [65]. 

Finally, it is worth mentioning that both complexes luminesce in the solid state both at room temperature and at 77 K, showing different luminescent behavior, the dioxane derivative being one of the still scarce blue luminescent materials. In contrast, the acetone complex is also luminescent in solution and shows a solvent dependence on the emission. Luminescence and conductivity measurements suggest that the Tl- -Tl interaction also exists in solution (probably stabilized by solvent molecules) and TD-DFT calculations seem to indicate that this interaction is responsible for luminescence in this case. This contrasts with other pentahalophenyl Au/Tl complexes, in which the optical properties are associated with the Au- -Tl contacts.149,151-154... 

Unfortunately, the acetone complex did not give clear answers about the validity of a dark, thermal H/D exchange process. Acetone solutions of the complex did not catalyze H2/D2 or D2/p-H exchange. The complex decomposes in the presence of water and in solutions other than acetone. 

Fig. 13. Possible isomers for the monosubstituted acetone complex. Calculated chemical shifts, given in parentheses, are in ppm and scaled to that of species 2 = —15.0 ppm.

Pluhakova K, Hobza P (2007) On the nature of the surprisingly small (red) shift in file halofiiane- acetone complex. Chem Phys Chem 8 1352—1356... 

The state of tin in Pt/Sn/alumina catalysts was investigated bv Li and Shia (25) via Mossbauer spectroscopy (i/9Sn enriched isotopes) and XPS. The former technique indicated the presence of Sn+, Sn+2 and Sn, in proportions that depended on the method of preparation, but in all cases the Sn+4 component dominated. These conclusions were confirmed by the XPS experiments. Additional TPR tests on the reduced catalyst and on samples exposed to air showed that reoxidation of Pt/Sn/alumina reduced preparations was rather slow, confirming our EXAFS observations. The presence of zero valent tin in similar preparations, using the acetone complexation procedure, was recently confirmed by Li, Stencel and Davis (12) in an extended XPS investigation. For reduced samples, with a Pt Sn ratio 1 5, these authors estimated that approximately 68% of the tin was in the metallic state. However, they observed that exposure of the sample to air for 10 minutes entirely eliminated the XPS detectable Sn°. Their data also indicated that upon reduction, chlorine migrated from the surface to the alumina. Thus, XPS which measures surface composition indicates a higher sensitivity to oxidation than was demonstrated by our EXAFS experiments, which is a bulk diagnostic. 

The effects of sulfonic acids on starch are discussed later (p. 375). Dimethyl sulfoxide and carbon disulfide are the only other sulfur-containing compounds that have been examined with respect to their complex formation with starch. For example, a complex of potato starch with carbon disulfide was prepared via the starch-acetone complex on refluxing. It was reported that this complex contains 5.8-5.9% of CS2.682 Dimethyl sulfoxide causes expanded coiling of amylose without the formation of a helix.378 Banks and Greenwood385 reviewed the Mark-Houwink exponent for Me2SO-starch solutions. Reported variations in this exponent are believed... 

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