Ketone complexes

This is in accordance with the primary kinetic isotope effect for Mn(III) sulphate With Co(III) electron abstraction may occur to give a radical-cation which suffers further oxidation. The alternative explanation of the lack of an isotope effect is that formation of the Co(III)-ketone complex is rate-determining this lacks, however, other kinetic support . ... 

Transfer hydrogenation of aldehydes with isopropanol without addition of external base has been achieved using the electronically and coordinatively unsaturated Os complex 43 as catalyst. High turnover frequencies have been observed with aldehyde substrates, however the catalyst was very poor for the hydrogenation of ketones. The stoichiometric conversion of 43 to the spectroscopically identifiable in solution ketone complex 45, via the non-isolable complex 44 (Scheme 2.4), provides evidence for two steps of the operating mechanism (alkoxide exchange, p-hydride elimination to form ketone hydride complex) of the transfer hydrogenation reaction [43]. 

Vahrenkamp and co-workers formed a number of chelate-stabilized ketone complexes with pyridylphenyl ketone. Octahedral complexes formed with a 2 1 ratio of ligand to zinc were formed with trifluoromethanesulfonate, chloride, and bromide anions. 1 1 reactions resulted in the formation of square pyramidal [ZnL2X]+ with X = Br, I, and a trigonal-bipyramidal dimer [L2Zn(NCS)2]2 with thiocyanate bridges.350... 

The complex OsH(OH)(CO)(P Pr3)2 also reacts with methyl acrylate, methyl vinyl ketone, and allyl alcohol.91 Reaction with methyl acrylate leads to OsH(OH) (COXrf-CH2=CHC02MeXP Pr3)2 containing the olefin trans to the hydride ligand. In solution, this complex releases the olefin to generate the starting complex. The thermodynamic magnitudes involved in the equilibrium have been determined in toluene-t/a by 31P 1H NMR spectroscopy. The values reported are AH° = 17.0 0.5 kcal-mor1 and AS° = 54.0 1.2 cal-K 1-mol 1. In the presence of the methyl vinyl ketone complex OsH(OH)(CO)(P Pr3)2 affords 0sH CHCHC(0) Me (CO)(P Pr3)2 and water, whereas in the presence of allyl alcohol the loss of... 

Hartmann P., Trettnak W., Effects of polymer matrices on calibration functions of luminescent oxygen sensors based on porphyrin ketone complexes, Anal. Chem. 1996 68(15) 2615-2620. 

Stoichiometric ionic hydrogenation of the C=C bond of a,/ -unsaturated ketones by HOTf and [Cp(CO)3WH] results in the formation of -ketone complexes of tungsten [32]. As exemplified in Eq. (17), hydrogenation of methyl vinyl ketone gives a 2-butanone complex of tungsten. The bound ketone is displaced by the triflate counterion, giving the free ketone. Similar reactions were reported for hydrogenation of the C=C bond of a,/ -unsaturated aldehydes. 

Carbon monoxide rapidly inserts into the carbon—zirconium bond of alkyl- and alkenyl-zirconocene chlorides at low temperature with retention of configuration at carbon to give acylzirconocene chlorides 17 (Scheme 3.5). Acylzirconocene chlorides have found utility in synthesis, as described elsewhere in this volume [17]. Lewis acid catalyzed additions to enones, aldehydes, and imines, yielding a-keto allylic alcohols, a-hydroxy ketones, and a-amino ketones, respectively [18], and palladium-catalyzed addition to alkyl/aryl halides and a,[5-ynones [19] are examples. The acyl complex 18 formed by the insertion of carbon monoxide into dialkyl, alkylaryl, or diaryl zirconocenes may rearrange to a r 2-ketone complex 19 either thermally (particularly when R1 = R2 = Ph) or on addition of a Lewis acid [5,20,21]. The rearrangement proceeds through the less stable... 

Dehydrogenation often occurred for the reactions of Cu+ and the formation of the ketone complex was common for the reaction of secondary alcohols with Ag+. Many of these ions react with alcohol to form a two-coordinate complex [M(ke-tone)(alcohol)]+. 

The majority of the studies in this series were performed using aliphatic and aromatic ketones as guests. The steroid sites that undergo functionalization vary with the guest used. Thus, irradiation of the DCA-diethyl ketone complex affords the product, 165, of addition of the ketone to the 6-equatorial position. Exposure of the DCA-cyclohexanone complex to light brings about formation of steroid functionalized in the D-ring, 166, while irradiation of the acetophenone complex affords the 5-fi-DCA adduct, 167. 

INT2, Scheme 10.7) undergoes further reaction (Li/Cu transmetalation) and generates a new organocuprate compound. (Note however that this difference could become more subtle since the product of conjugate addition (PD) might behave more like an a-cuprio(I) ketone complexed with a lithium cation [52] than a lithium enolate complexed with copper(I)). In neither reaction was any evidence of radical intermediates (i.e., SET) found by theoretical calculations [79]. 

The effect of ring substituents on the rate constants, deuterium kinetic isotope effects and Arrhenius parameters for ene-additions of acetone to 1,1-diphenylsilane have been explained in terms of a mechanism involving fast, reversible formation of a zwitterionic silene-ketone complex, followed by a rate-limiting proton transfer between the a-carbonyl and silenic carbon. A study of the thermal and Lewis acid-catalysed intramolecular ene reactions of allenylsilanes with a variety of... 

Ketonate complexes of Ru are reported in a number of papers. The parent complex [Ru(acac)3] has been subject to a polarized neutron diffraction study at 4.18 K, to powder neutron diffraction studies and to single-crystal structure determinations at 293 K, 92 K, and 10.5 K. The structure is disordered at all temperatures. Measurements of the magnetic susceptibilities (at 2.5 K and 300 K) have been made along different crystal axis directions, and the results analyzed. An investigation of the relationships between ionization potentials and half-wave potentials of a series of tris(/3-ketonate)Ru complexes has been reported, and the electrochemical properties of [Ru(acac)3] in chloroaluminate molten salt media have been reported. The reduced species [Ru(acac)3] can react with AICI4 reduction by bulk electrolysis of a small amount of [Ru-(acac)3] in the melt yields [RuClg]. ... 

Table 68 Some Ketone Complexes of DioxouraniumfVl) Compounds...

First reported in 1986 (181), the complex [Os(NH3)5(acetone)]2+ and related aldehyde and ketone complexes (177) were the first examples of linkage isomerizations on Os(III/II). In acetone solution, a detailed electrochemical and chemical investigation revealed that the substi-tutionally inert complex, [Os(NH3)5(Tj2-acetone)]2+, is in facile equilibrium with the rj1 form, the former being favored by 21 kJ mol-1. Upon oxidation, the Os—C bond is ruptured, but the Os—O bond remains intact, even in good donor solvents such as dma. Reduction of the i71-acetone-Os(III) species occurs at a potential of 750 mV negative of that of the 172 form in acetone. Subsequent tj1 - 172 isomerization of the ketone occurs with a specific rate of 6 x 103 sec-1 at 20 2°C. 

A crystal structural analysis of the bisimidazolyl ketone complex (56) has been made, and the metal shown to be in an approximately tetrahedral environment.434... 

Di-2-pyridyl ketone complexes to Zn2+ in an N,N-chelate fashion, while the keto group is present in the form of the geminal diol. In basic solution, this latter group is ionized, leading to A, O-coordination by the ligand.529... 

The partition of HC1 and HN03 into oxygen donor solvents almost invariably involves the partition of a solvated species and many salts (notably perchlorates and thiocyanates) extract well into the higher alcohols and ketones. Complex nitrates such as that of Ce,v may extract as... 

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