Acetylacetonato Complexes Research Articles

Kinetics of the substitution reactions of β-diketonato-1,5-cyclo-octadieneiridium(I) complexes with derivatives of 1,10-phenanthroline and 2,2′-dipyridyl

The reaction between various [Ir(β-dik)(COD)] complexes and derivatives of 1,10-phenanthroline and 2,2′-dipyridyl (NN) to give the five-coordinated carbon-bonded β-diketonato complex [Ir(β-dik-C3(NN)(COD)] has been studied in an acetone medium. The rate constants increase from 1.36 × 101 for the acetylacetonato complex to 3.0 × 106 M−1 s−1 for the hexafluoroacetylacetonato complex. The observed rate law is R = k[Ir(β-dik)][NN]. The observed linear free energy relationship (the plot of log k versus the pKa of the β-diketone has a slope of -0.95) as well as the large negative values for the entropy of activation suggest an associative mechanism. The basicity of the incoming ligand plays only a minor role. The much higher value of k for the reaction with 2,2′-dipyridyl is attributed to the lower rigidity of 2,2′-dipyridyl. The results indicate that the rate determining step in the formation of the carbon-bonded β-diketonato complex is the associative attack of the incoming amine ligand.

Mobilities of metal β‐diketonato complexes in micellar electrokinetic chromatography

AbstractElectrically neutral acetylacetonato complexes of chromium(III), cobalt(III), rhodium(III), and platinum(II) (or palladium(II)) have been separated successfully by capillary zone electrophoresis in a micellar solution of sodium dodecyl sulfate (SDS). The distribution coefficient of each metal complex between the SDS micelle and the aqueous solution surrounding the micelle was calculated from the capacity factor. A linear log‐log relationship was found between the distribution coefficient and the partition coefficient of the complex between dodecane and water. The linear relationship was effectively used for prediction of both the distribution coefficients and the migration times of other metal complexes, such as palladium(II) acetylacetonate and chromium(III) 3‐methyl acetylacetonate.

Application of the stabilized zirconia thin film prepared by spray pyrolysis method to SOFC

Thin films of calcia-stabilized zirconia were fabricated from Zr and Ca acetylacetonato complexes on a La 0.6Sr 0.4MnO 3 porous electrode substrate by spray pyrolysis method. Although the cracks formed in the film during drying, thermal decomposition, and heat treatment, they could be eliminated by optimizing the substrate temperature and repeating the film deposition and heating cycle. The fuel cell consisting of 33 μm thick electrolyte, La 0.6Sr 0.4MnO 3 porous cathode substrate, and Ni-YSZ cermet anode attained the open circuit voltage of 0.96 V and maximum power density of 0.5 W·cm −2.

ChemInform Abstract: Cyclometalated Compounds. Part 4. Cyclopalladation of Phenylpyrimidines and X‐Ray Structure of a Doubly Cyclopalladated Derivative of 4,6‐Diphenylpyrimidine.

AbstractThe cyclopalladated dichloro compounds are characterized by 1H and 13C NMR studies of their acetylacetonato complexes.

Reactivity and reaction mechanism of acetylacetonato complexes of tervalent metal ions in solution

Reactivity and reaction mechanism of acetylacetonato complexes of tervalent metal ions in solution

Photodissociation of jet-cooled acetylacetonato complexes of the first transition metals. Free metal generation and fragmentational ionization

Photodissociation of jet-cooled acetylacetonato complexes of Sc(III), Mn(III), Fe(III), Co(III), Ni(II), Cu(II), Zn(II), Al(III), and Ga(III) is studied by multiphoton dissociation/ionization mass spectroscopy. Efficient generation of the neutral Cu atom from the Cu(II) complex is found to occur after two-photon excitation with UV light. Two-color laser photolysis shows that the Cu atom generation is due to homolytic dissociation of all the metal-ligand bonds occurring in the super-excited state of the Cu(II) complex. The threshold energy of the two-photon dissociation is obtained and the energetics of the photolysis of the Cu(II) complex is given on the basis of the results. For other metal complexes it is found that extensive fragmentational ionization takes place under a similar excitation condition to that of the Cu(II) complex while free metal atom generation does not occur. The characteristic free metal generation occurring in the Cu(II) complex is discussed in connection with the photolysis of the Cr(III) complex which was reported in a previous paper.

ChemInform Abstract: Triaza Analogue of an Acetylacetonato Complex Formed by Nucleophilic Attack of a Coordinated Nitrile by Amidines. X‐Ray Crystal Structure of (Pt(HNC(Ph)NC(Ph)NH)2)· 2/3 PhMe.

ChemInformVolume 20, Issue 36 Organoelement Compounds ChemInform Abstract: Triaza Analogue of an Acetylacetonato Complex Formed by Nucleophilic Attack of a Coordinated Nitrile by Amidines. X-Ray Crystal Structure of (Pt(HNC(Ph)NC(Ph)NH)2)· 2/3 PhMe. J. BARKER, J. BARKER Dep. Chem., Univ. Durham, Durham DH1 3LE, UKSearch for more papers by this authorM. KILNER, M. KILNER Dep. Chem., Univ. Durham, Durham DH1 3LE, UKSearch for more papers by this authorM. M. MAHMOUD, M. M. MAHMOUD Dep. Chem., Univ. Durham, Durham DH1 3LE, UKSearch for more papers by this authorS. C. WALLWORK, S. C. WALLWORK Dep. Chem., Univ. Durham, Durham DH1 3LE, UKSearch for more papers by this author J. BARKER, J. BARKER Dep. Chem., Univ. Durham, Durham DH1 3LE, UKSearch for more papers by this authorM. KILNER, M. KILNER Dep. Chem., Univ. Durham, Durham DH1 3LE, UKSearch for more papers by this authorM. M. MAHMOUD, M. M. MAHMOUD Dep. Chem., Univ. Durham, Durham DH1 3LE, UKSearch for more papers by this authorS. C. WALLWORK, S. C. WALLWORK Dep. Chem., Univ. Durham, Durham DH1 3LE, UKSearch for more papers by this author First published: September 5, 1989 https://doi.org/10.1002/chin.198936320Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume20, Issue36September 5, 1989 RelatedInformation

ChemInform Abstract: Oxovanadium(IV) and Dioxomolybdenum(VI) Complexes: Synthesis from the Corresponding Acetylacetonato Complexes and X‐Ray Structures.

AbstractDisplacement of acac from MoO2(acac)2 or VO(acac)2 in the reaction with the acidic form of the substituted 7,16‐dihydro‐tetraazatetradecine is a stepwise process.

Nuclear magnetic resonance relaxation studies on the preferential solvation of tris-acetylacetonato–chromium(III) in bromoform–carbon tetrachloride solutions

N.m.r. relaxation has been used to study the solvation of tris-acetyl-acetonoato-chromium(III)[Cr(acac)3] with bromoform in solutions. The temperature-dependent stability constant of the solvated complex has been determined in the region of dilute bromoform solutions. The results have been used to interpret the deuteron relaxation data in the corresponding perdeuterated solution of Co(acac)3. A solvation number of two is found in the temperature range 285–325 K. The distance between the chromium ion and the proton (or carbon atom) of solvated bromoform was found to be 3.6 A( or 4.6 A). This evidence indicates the formation of a trifurcated hydrogen bond between bromoform and the acetylacetonato complex. Compared with the chloroform solvent system, larger stability constants have been found in this study. The results are successfully applied to the estimation of deuteron relaxation rates in the perdeuterated solutions of Cr(acac)3 and to the evaluation of the differential line broadening effects on deuteron split 13C triplets of CDBr3 molecules.

Oxovanadium(IV) and dioxomolybdenum(VI) complexes: synthesis from the corresponding acetylacetonato complexes and X-ray structures

Displacement of acetylacetonate (acac) from oxometal complexes of this ligand in the reaction with the acidic form of 7,16-dihydro-6,8,15,17-tetramethyldibenzo[b,I][1,4,8,11] tetra-azacyclotetra-decine (H2L) is a stepwise process. The reaction of [MoO2(acac)2] with H2L in tetrahydronaphthalene gave a partial displacement of the acetylacetonato ligand and formation of [MoO2(acac)(HL)](1). Two nitrogen atoms only from the macrocycle bind molybdenum, which is six-co-ordinate with the two oxo groups in a cis arrangement [ν(Mo–O)895 and 927 cm–1]. A complete displacement of the acetylacetone occurs in [VO(acac)2] leading to the formation of [VO(L)](2). Vanadium has a pseudo-square-pyramidal co-ordination geometry in (2), with the L ligand assuming the usual ‘saddle’ shape conformation [ν(V–O) 978 cm–1]. The structures of (1) and (2) have been determined by X-ray analysis.

ChemInform Abstract: Role of the Nature of the Metal Center in the Catalyzed Addition of β‐Dicarbonyls to Electrophilically Activated Nitriles.

AbstractThe catalytic efficiency of a series of acetylacetonato complexes in the reaction of (I) with (II) is estimated quantitatively.

ChemInform Abstract: Facile Deprotonation of Coordinated Bis(diphenylphosphino)methane by an Acetylacetonate Anion.

AbstractThe reactions of the acetylacetonato complexes (I) and (V) with bis(diphenylphosphino)methane (II) lead to the unexpected formation of the polymeric (III) or monomeric complexes (VII) containing coordinated bis(diphenylphosphino)methanide.

ChemInform Abstract: Synthesis and Structure of Three (Tricyclohexylphosphine)rhodium Complexes and Their Interconversion with Carbon Monoxide and Hydrogen.

AbstractThe reaction of the acetylacetonato complex (I) with CO and H2 in the presence of tricyclohexylphosphine gives an easily separated mixture of the trans‐square‐planar complex (II) and the binuclear complex (III) with a square‐planar Rh(CO)PCy3 and a distorted‐tetrahedral Rh(PCy3)2 unit.

Redox reactions with metal carbonyls of group V

AbstractThe carbonylmetalates of cobalt(‐I), manganese(‐I), chromium(‐I), molybdenum(‐I), tungsten(‐I), and the anionic carbonyl cyclopentadienyl derivatives of the zerovalent Group VI metals ([MCp(CO)3]−, M = Cr, Mo, W) are readily oxidized by hexacarbonylvanadium(0) to give the neutral metal carbonyls. In the case of the V(CO)6/[Mn(CO)5]− system, by 13CO‐labeling of the oxidizing agent V(CO)6 it is shown that the redox reaction occurs via an outer‐sphere mechanism. On the other hand, hexacarbonylvanadium(0) behaves as a reducing agent towards NiCp2 and MnCp2, the reduced products being Ni(CO)4 and MnCp(CO)3, respectively. The hexacarbonylmetalates of niobium(‐I) and tantalum(‐I) are oxidized by a number of oxidizing agents, exclusively by a two‐electron transfer process to niobium(I) and tantalum(I). When the acetylacetonato complexes of nickel(II) and iron(III) are used as oxidizing agents, the M(acac)(CO)4 THF complexes (M = Nb, Ta) were obtained, the oxidation by nickel(II) being the preferred one from a preparative point of view. The crystal and molecular structure of the tantalum complex, Ta(acac)(CO)4 THF, has been solved by X‐ray diffraction methods. Crystals are orthorhombic, space group P212121, a = 15.347(3), b = 12.227(3), c = 8.642(3)Å, V = 1621.6 Å3, Dc = 1.900 g·cm−3, Z = 4. The tantalum atom is heptacoordinated, being surrounded by the bidentate acetylacetonato ligand, by four carbon monoxide groups, and by the oxygen atom of the THF ligand. The THF ligand of the complexes is easily substituted, together with one of the carbonyl groups, by isocyanides, and a bidentate tertiary phosphane, while with the monodentate triphenylphosphane a substitutional equilibrium is established.

Reactions of the [PtC2L2] Complexes (L=Sulfide or Tertiary Phosphine) with β-Diketonate Anions

Abstract cis- and trans-[PtCl2(Et2S)2] as well as [PtCl2(EtSCH2CH2SEt)] reacted with thallium(I) β-diketonates, Tl(β-dik), to give complexes containing a central-carbon-bonded β-dik ligand. The reaction of cis-[PtCl2(PEt3)2] with Tl(acac) (acac=acetylacetonato) did not give an acetylacetonato complex, but resulted in [Pt(CO3)(PEt3)2], while trans-[PtCl2(PEt3)2] yielded [PtCl(acac)(PEt3)]. [Pt(PPh3)2(H2O)2](ClO4)2 derived from cis-[PtCl2(PPh3)2] reacted with K(acac) and K(tfac) (tfac=trifluoroacetylacetonato) to afford [Pt(acac)(PPh3)2]ClO4 and [Pt(tfac)(PPh3)2]ClO4, respectively. Bases such as Et3N, K(acac), and K(tfac) removed a proton from the latter complex to give [Pt(tfac(2–)-C,O)(PPh3)2] containing a C,O-chelated tfac dianion.

Preparation, Stereochemistry, and Kinetics of Isomerization and Racemization of Acetylacetonato Complexes of Chromium(III) Containing 2,2′-Bipyridine N,N′-Dioxide or Its 3,3′-Dimethyl Derivative

Abstract New acetylacetonato (acac) chromium(III) complexes of the type, [Cr(acac)3−nLn]n+ (n=1 and 2), where L denotes a seven-membered chelate ligand, 2,2′-bipyridine N,N′-dioxide (bpdo) or 3,3′-dimethyl-2,2′-bipyridine N,N′-dioxide (rac- or R-mbdo), were prepared. Optically active [Cr(acac)2(R-mbdo)]+ and [Cr(acac)(R-mbdo)2]2+ yielded only one isomer and were assigned to Δ(λ)(lel) and Δ(λλ)(lel2), respectively, on the basis of the circular dichroism spectra and molecular models. The [Cr(acac)(mbdo)2]2+ complex prepared from rac-mbdo formed two racemates of diastereomers, lel2(Δ(λλ), Λ(δδ)) and lel·ob (Δ(λδ)), Λ(δλ), whereas [Cr(acac)2(bpdo)]+ formed only lel(Δ(λ), Λ(δ)) isomer which was resolved by column chromatography. Both rac- and (−)589[Cr(acac)(bpdo)2](ClO4)2·H2O resolved by a chemical method were found to crystallize in lel2 isomer, but isomerize to the isomer in aqueous solution with the rate of 3.31×10−3 s−1 at 295.2 K, the rate constant for racemization (Δ\ightleftarrowsΛ) being 1.08×10−4 s−1 at 295.2 K. An intramolecular conformational inversion of the bpdo chelate ring for the isomerization and an intramolecular twist mechanism for the racemization were proposed.

Regularities of the Partition Coefficients of Bis, Tris, and Tetrakis(acetylacetonato)metal (II, III and IV) Complexes

AbstractThe partition coefficients of seven acetylacetonato complexes, Pt(acac)2, Pd(acac)2, Be(acac)2, VO(acac)2, Cr(acac)3, Al(acac)3 and Co(acac)3 and those of trifluoroacetylacetone (Htfa) and Be(tfa)2 were determined at 25°C employing dodecane, carbon tetrachloride, and/or benzene as an organic phase. The molar volumes of acetylacetonato complexes which include bis, tris and tetrakis complexes were also determined from precise density measurement at 25°C. Linear correlations between the partition coefficients of acetylacetone (enol form) and those of the bis, tris, and tetrakis complexes which include some available literature data were obtained, and interpreted in the frame of the modified regular solution equation which has a binary coefficient introduced to improve the simple geometric mean assumption. On the main factor governing the partition equilibrium, a general importance of cavity formation energy was concluded by comparison with the scaled particle calculation. Hydration in the bis complexes was suggested as an additional factor to govern partition coefficient.

Grafting Vinyl Monomers onto Chemically Modified Wool Fibers: Graft Copolymerization of Methyl Methacrylate onto Reduced Wool Fibers Using Acetylacetonate Complex of Manganese(III)

Abstract The graft copolymerization of methyl methacrylate (MMA) onto reduced Indian Chokla wool fibers was studied in aqueous solution using the acetylacetonato complex of Mn(III) as the initiator. Perchloric acid was found to catalyze the reaction. The rate of grafting was investigated by varying the concentration of the monomer and the complex, acidity of the medium, the temperature, and the reaction medium. It is observed that the graft yield increases with increasing concentration of the chelate and acid and with increasing temperature. There is an increase in graft yield within a certain concentration range of the monomer, after which it falls. The grafting is considerably influenced by changing the solvent composition of the reaction medium. A comparative study reveals that oxidized and reduced wools are better substrates than untreated and other chemically modified wools. The effect of various monomers on graft yield is investigated. MMA is found to be a most active monomer compared to other vinyl...

Oxidative addition of dialkylphosphites to complexes of iridium(I) and rhodium(I)

The PH bond of dialkylphosphites (dimethylphosphite, 5,5-dimethyl-1,3-dioxa-2-phosphorinane and 4,4,5,5-tetramethyl-1,3-dioxa-2-phospholane) oxidatively adds to irClL 2(L = PPh 3, AsPh 3) and IrCl(PMe 2Ph) 3 generated in situ to give six-coordinate hydrido(dialkylphosphonato)iridium(III) complexes, e.g. IrHClL 2[{(MeO) 2-PO} 2H] and IrHCl(PMe 2Ph) 3[PO(OMe) 2]. Addition of triphenylphosphine to a solution containing [IrCl(C 8H 14) 2] 2 and dimethylphosphite in a 1:2 mol ratio gives a five-coordinate hydrido (dimethylphosphonato)iridium(III) complex IrHCl(PPh 3) 2{PO(OMe) 2}, from which six-coordinate pyridine and acetylacetonato complexes IrHCl(PPh 3) 2(C 5H 5N){PO(OMe) 2} and IrH(PPh 3) 2(acac){PO(OMe) 2} can be obtained. The ligand arrangements in the various complexes are inferred from IR, 1H and 31P NMR data.

Cumene hydroperoxide decomposition in the presence of MoO 2 2+ acetylacetonato complex supported on an inorganic matrix

Decomposition of cumene hydroperoxide in the presence of the acetylacetonate complex of MoO 2 2+ supported on a matrix of SiO2 has been studied. The reaction is first order with respect to the catalyst. The initial rate remains unchanged at concentration at cumene hydroperoxide concentrations above 0.08 mol/dm3. A two-stage mechanism of hydroperoxide decomposition is suggested.