Showing papers in "Transition Metal Chemistry in 1991"
TL;DR: The complexes MHCl(CO) (AsPh3)3 (1: M=Ru and 2: M = Os) as mentioned in this paper readily react with Ph2PCH2CH2AsPh2 (Arphos) and with acetic acid to produce MCl( CO) (OCOMe)(AsPh 3)2 (5: M-Ru and 6: O-Os).
Abstract: The complexes MHCl(CO)(AsPh3)3 (1: M=Ru and2: M=Os) readily react with Ph2PCH2CH2AsPh2 (Arphos) to yield MHCl(CO) (AsPh3) (Arphos) (3: M=Ru and4: M=Os) and with acetic acid to produce MCl(CO) (OCOMe) (AsPh3)2 (5: M=Ru and6: M=Os); the new compounds were characterized by elemental analysis, i.r. and1H n.m.r. spectroscopy. Complexes (1−6) are efficient catalyst precursors for the homogeneous hydrogenation of the C=O bond of propionaldehyde under moderate reaction conditions; some relations between structures and catalytic activities are described, as well as comparisons with analogous systems containing phosphine ligands.
98 citations
TL;DR: In this paper, the authors focus on the reactions stoechiometriques and des reactions catalytiques and present an article concerned with des complexes contenant des derives du silicium.
Abstract: Revue des travaux des annees 1987 a 1990, concernant des complexes contenant des derives du silicium. L'article porte principalement sur les reactions stoechiometriques et des reactions catalytiques. Synthese bibliographique.
57 citations
TL;DR: In this article, the physical and spectral properties of 3-pyrrolidinylthiosemicarbazones of 2-acetylpyridine (2-Pyridine) and N-oxide have been determined.
Abstract: Copper(II) complexes of the 3-pyrrolidinylthiosemicarbazones of 2-acetylpyridine and 2-acetylpyridineN-oxide have been prepared and their physical and spectral properties determined. Growth inhibition ofAspergillus niger, Paecilomyces variotii, Penicillium rubrum, andAspergillus terreus by thiosemicarbazones and their copper(II) complexes has been measured. These results are compared to 2-acetylpyridine 3-azacyclothiosemicarbazone ligand complexes.
51 citations
TL;DR: The terdentate character of the ligand in all cases is inferred from i.r. spectra, while the electronic spectra suggest planar geometries as discussed by the authors.
Abstract: NiII complexes of 1H-hexahydroazepine-1-thiocarboxylic acid-2-[1-(2-pyridinyl)ethylidene] hydrazide (HL4A) of general formula [Ni(L4A)X] (X=Cl, Br, I or NCS) have been synthesized and characterised by physical and spectroscopic methods. The molar conductivities show that all of the complexes are non-electrolytes. The terdentate character of the ligand in all cases is inferred from i.r. spectra, while the electronic spectra suggest planar geometries.
51 citations
TL;DR: In this paper, the authors highlight recent advances in the field of catalytic homogeneous oxidations of organic substrates by polyoxometallates and underline the pressing need for a more detailed understanding of how these oxidations occur.
Abstract: The study of catalytic homogeneous oxidations of organic substrates by polyoxometallates, i.e. isopolyanions and, in particular, heteropolyanions is a fast growing area of both academic and industrial interest. This brief account is intended to highlight recent advances in the field and to underline the pressing need for a more detailed understanding of how these oxidations occur. The literature on the subject up to 1987 has been comprehensively covered by Kozhevnikov and Pope has produced excellent reviews on the anions
42 citations
TL;DR: In this article, two series of copper(II) complexes, [Cu(HL)X2] and [CU(L)Cl], where HL is a 2-formylpyridine4N-substituted thiosemicarbazone, L is an anion formed by loss of the 2N hydrogen and X=Cl or Br, have been prepared and spectrally characterised.
Abstract: Two series of copper(II) complexes. [Cu(HL)X2] and [Cu(L)Cl], where HL is a 2-formylpyridine4N-substituted thiosemicarbazone, L is an anion formed by loss of the2N hydrogen and X=Cl or Br, have been prepared and spectrally characterised. Their growth inhibition ofAspergillus niger andPaecilomyces variotii has been measured and compared with analogous complexes formed from 2-acetylpyridine thiosemicarbazones.
42 citations
TL;DR: In this article, the structure of the vicinal dioxime and its complexes are proposed on the basis of elemental analysis, i.m.r., 1H-n.m., and uv-visible measurements.
Abstract: 2,3-Bis(hydroxyimino)-1,2,3,4-tetrahydro-pyrido[2,3-b]pyrazine (H2L), prepared from 2,3-diaminopyridine and cyanogen-di-N-oxide has been converted into nickel(II), palladium(II), copper(II), cobalt(II), and cobalt(III) complexes (H2L) with a 1∶2 metal:ligand ratio. The ligands coordinate through the two N atoms, as do most vicinal dioximes. [(LH)Cl(H2O)Cd], contains a six-membered chelate ring. [Co(HL)2(L′)Cl] has also been prepared using triphenylphosphine, triphenylarsine, thiophene and chloride as axial ligands. The structure of thevic-dioxime and its complexes are proposed on the basis of elemental analysis, i.r.,1H-n.m.r. and uv-visible measurements.
37 citations
TL;DR: In this paper, the Mo:cit ratio of molybdate and citric acid (H4cit) at pH 4-8 has been characterized by a variety of methods in the solid state and in solution.
Abstract: The complexes obtained by crystallisation from an aqueous solution of molybdate and citric acid (H4cit) at pH 4–8 have Mo:cit ratio 1∶1. The new complexes have been characterised by a variety of methods in the solid state and in solution. On this basis two dimeric species, [(MoO2)2O(citH)2]4− and [(MoO2)2O(cit)2]6−, and a monomeric species [MoO3(cit)OH2]4− are proposed.
34 citations
TL;DR: In this article, a triclinic space group was used to synthesize a trans-Methyliodo-8-hydroxyquinolinatocarbonyltriphenylphosphinerhodium(III) by means of the oxidative addition of MeI.
Abstract: trans-Methyliodo-8-hydroxyquinolinatocarbonyltriphenylphosphinerhodium(III) was synthesised by means of the oxidative addition of MeI to 8-hydroxyquinolinatocarbonyltriphenylphosphinerhodium(I). The compound crystallizes in the triclinic space group,
$$P\bar 1$$
, witha=13.423(5),b=14.500(3),c=17.562(5)A, α=68.30(2), β=75.15(2), γ=86.31(2)°. The final R value was 0.052 for the 11302 observed reflections. There are two [Rh(ox)(CO)(PPh3)(Me)(I)] and one Me2CO molecule in the asymmetric unit. The rhodium atom has an octahedral configuration with the methyl and iodide ligands in thetrans positions. This structure determination showed that only the alkyl complex is formed during the oxidative addition reaction and thattrans-addition of MeI occurs.
32 citations
TL;DR: Complexes of CoII, NiII, CuII, PdII, and PtIV with 2,4,5-trihydroxybenzoic acid and its substituted phenylazoderivatives have been prepared, together with some mixed-metal (Co, Cu or Ni, Cu) complexes of itsm-nitro,m-carboxy andm-hydroxyarylazo derivatives as mentioned in this paper.
Abstract: Complexes of CoII, NiII, CuII, PdII, and PtIV with 2,4,5-trihydroxybenzoic acid and its substituted phenylazoderivatives have been prepared, together with some mixed-metal (Co, Cu or Ni, Cu) complexes of itsm-nitro,m-carboxy andm-hydroxyarylazo derivatives. The stereochemistries and the modes of bonding of the complexes were elucidated by spectral and magnetic susceptibility measurements.
31 citations
TL;DR: In this article, the thermal stabilities of the polymer complexes were compared with the homopolymer and the activation energies of degradation were calculated by elemental analyses, ir and electronic spectroscopic, and magnetic moment measurements.
Abstract: Poly(5-vinyl salicylidene)-2-aminophenol homopolymer and polymer complexes of 5-vinyl salicylidene-2-aminophenol with transition metal acetates have been prepared and characterised by elemental analyses, ir and electronic spectroscopic, and magnetic moment measurements The thermal stabilities of the polymer complexes were compared with the homopolymer and the activation energies of degradation were calculated
TL;DR: Quasireversible copper(II)/copper(I) couples were observed for [Cu(L)X], where X=Cl or Br, and L=an anion of a 2-acetylpyridine4N-dialkylthiosemicarbazone as discussed by the authors.
Abstract: Quasireversible copper(II)/copper(I) couples are observed for [Cu(L)X], where X=Cl or Br, and L=an anion of a 2-acetylpyridine4N-dialkylthiosemicarbazone Irreversible reduction potentials of the tridentate (NNS) ligands increase as the size of the4N-dialkyl-substituent increases The growth inhibitory activity of the complex againstPaecilomyces variotii (but not other fungi tested) also decreases with increasing ligand size, suggesting that ease of ligand reduction is a significant factor in activity against this fungus
TL;DR: In this article, the nitrogen atom of the chelate ring has the largest trans influence since the carbonyl grouptrans to this atom was substituted by the PPh3 ligand.
Abstract: 2-Carboxyquinolinatocarbonyltriphenylphosphinerhodium(I), [Rh(Quin)(CO)(PPh3)], was prepared by replacement of CO by PPh3 in the corresponding dicarbonyl. The compound crystallizes in the triclinic space group
$$P\bar 1$$
Ab=17.168(6) A,c=9.254(5) A, α=101.49(5)°, β=95.74(4)°, γ=98.41(4)°, dcxp=1.45g cm−3 and Z=2. The crystal structure was dermined from 3496 observed reflections. The final R value was 0.061. This structure determination indicates that the nitrogen atom of the chelate ring has the largesttrans influence since the carbonyl grouptrans to this atom was substituted by the PPh3 ligand. The effects of different donor atoms in bidentate ligands, as well as the ring size of the chelate ring, on the relativetrans influence of the donor atoms are discussed.
TL;DR: The complexes [Ru(LL)3]-PF6] (PF6)2 [LL=2,2′-bipyridine (bipy), 1,10-phenanthroline (phen) and 4,4′-di-terbutyl-2, 2′-, 2,2''-Bipy* were synthesised using microwave dielectric loss heating effects as discussed by the authors.
Abstract: The complexes [Ru(LL)3](PF6)2 [LL=2,2′-bipyridine (bipy), 1,10-phenanthroline (phen) and 4,4′-di-terbutyl-2,2′-bipyridine (bipy*)] and [Ru(terpy)2] (PF6)2 (terpy=2,2′,2″-terpyridine) have been rapidly and conveniently synthesised using microwave dielectric loss heating effects The compounds were prepared in good yields (60–94%) in a Teflon autoclave, which can sustain temperatures up to 250°C and pressures of 80 atm, using MeOH as a solvent Two 20s exposures to microwaves (2450 MHz and 650 W) were sufficient to achieve these yields
TL;DR: In this article, the rate of CrIII oxidation at 27°C was shown to follow the rate law and the formation constant of [Cr(OH)4]− from soluble Cr(OH)-3 was determined at 27.0°C, presumably due to slow formation of polynuclear CrIII species.
Abstract: Alkaline hexacyanoferrate(III) oxidation of freshly prepared solutions of CrIII (pH>12) at 27°C follows the rate law, Equation 1:
1
$$Rate = \frac{{kK_{OH} [Fe(CN)_6 ]^{3 - } [Cr^{III} ]_T [OH^ - ]_T }}{{(1 + K_{OH} [OH^ - ]_T )}}$$
[Fe(CN)6]3− and [Cr(OH)4]− are the active species. The values of KOH(1.62±0.02 dm3 mol−1) and k (2.5±0.2 dm3 mol−1s−1), the formation constant of [Cr(OH)4]− from soluble Cr(OH)3 and the rate constant respectively, were determined at 27.0°C. The solubility of CrIII at pH>12 decreases with time, presumably due to slow formation of polynuclear CrIII species.
TL;DR: In this article, the influence of penta and tetracyanooxomolybdenum (IV) anions on the reactivity of the complex, especially towards O2, is discussed.
Abstract: Several penta-and tetracyanooxomolybdenum(IV) anions have been synthesized containing different numbers of H2O molecules, either coordinated or present as crystallisation molecules. The influence of these molecules on the reactivity of the complex, especially towards O2, is discussed. Three compounds were characterized by x-ray structure determination. [Mo(O)(CN)5(H2O)2(MeCN)2][PPh4]4Cl belongs to triclinic space group P-1 witha=13.146(3) A,b=16.944(5) A,c=21.761(6) A, α=84.72(2)°, β=87.15(2)° and γ=85.25(2)°. The volume of the unit cell is 4678(6)A3 withz=2. The structure was refined to R=6.5%. [Mo(O)(CN)4(H2O)·6H2O][PPh4]2 belongs to monoclinic space group P21/n witha=15.313(2)A,b=19.983(3)A,c=17.006(2)A, β=100.51(2)°. The volume of the unit cell is 5117(3)A3 withz=4. The structure was refined to R=8.7%. [Mo(O)(CN)4(MeCN)](PH3)2N]2 belongs to triclinic space group P-1 witha=13.770(4)A,b=16.292(5)A,c=16.889(5)A, α=73.23(2)°, β=72.02(2)° and γ=71.57(2)°. The volume of the unit cell is 3342(3)A3 withz=2. The structure was refined to R=7.2%.
TL;DR: The structure of the tetrahydrate of the tris-ligand FeII complex of the Schiff base derived from 2-acetyl pyridine and methylamine has been established by x-ray diffraction methods as mentioned in this paper.
Abstract: The structure of the tetrahydrate of the nitroprusside salt of the tris-ligand-FeII complex of the Schiff base derived from 2-acetyl pyridine and methylamine has been established by x-ray diffraction methods. The cation has themer-configuration in this salt in the solid phase. Kinetic and spectroscopic, particularly1H n.m.r., results indicate that bothmer-andfac-isomers of this, and of related complexes, have to be considered in solution. Kinetics of base hydrolysis of the title cation, and its solvation, in MeOH-H2O mixtures are described and compared with those for other low-spin FeII-diimine complexes.
TL;DR: The crystal structure of (PPh4)3[ReN(CN)5]·7H2O has been determined from three dimensional X-ray diffraction data as mentioned in this paper.
Abstract: The crystal structure of (PPh4)3[ReN(CN)5]·7H2O has been determined from three dimensional X-ray diffraction data. The orange crystals are triclinic, space group\(P\bar 1\), with cell dimensions a=12.514(3), b=15.8514), c=19.030(3) A, α=77.62(2), β=84.61(1) and γ=74.03(2)o, z=2, Dobsd=1.40(1) g cm−3 and Dcalc=1.37(1) g cm−3. The anisotropic refinement of 5861 observed reflections converged to R=0.049.
TL;DR: In this article, the reactions of 2,2′-biquinoline(biq) with M(PhCN)2X2 (M=Pd; X=Cl or Br; M=Pt, X =Cl, Br or I), K2PtCl4 and RhCl3·3H2O have been investigated.
Abstract: The reactions of 2,2′-biquinoline(biq) with M(PhCN)2X2 (M=Pd; X=Cl or Br; M=Pt, X=Cl, Br or I), K2PtCl4 and RhCl3·3H2O and of 2-(2′-pyridyl)quinoline (pq) with K2PtCl4 and RhCl3·3H2O have been investigated The isolated complexescis-[Pd(biq)X2] (X=Cl or Br),cis-[Pt(biq)Cl2],cis-[Pt(biq)Cl2]·H2O,trans-[Pt(biq)2Br2]·5H2O, [Pt3(biq)2I6],mer-[Rh(biq)Cl3-(H2O)] andmer-[Rh(pq)Cl3(H2O)] have been characterized by elemental analyses, conductivity measurements, ir, electronic, and1H nmr spectra The reaction of pq with K2PtCl4 in 1M H2SO4 gave the salt 2-(2′-pyridyl) quinolinium tetrachloroplatinate(II) pentahydrate, (pqH)2[PtCl4]·5H2O; when the reaction was carried out in aqueous acetone,cis-[Pt(pq)Cl2] was obtained A new method for the synthesis ofcis-[Rh(biq)2X2]X (X=Cl or Br) is described; both compounds have been further characterized by1H nmr
TL;DR: The thiolato-bridged dinuclear compounds [Rh(μ-SR)-(COD)]2, where R=p-C6HF4 and CF3 (3), are obtained from the chloro-bridging analogue by ligand exchange Compound (1) crystallizes in the space group P1 with a=9740(3)A, b=11642(4)A and c=13997(6)A; z=2 In this dinuclear molecule both Rh atoms have a square planar coordination sharing one edge, namely the two
Abstract: The thiolato-bridged dinuclear compounds [Rh(μ-SR)-(COD)]2, where R=p-C6HF4 (1),p-C6H4F (2) and CF3 (3), are obtained from the chloro-bridged analogue by ligand exchange Compound (1) crystallizes in the space group P1 with a=9740(3)A, b=11642(4)A, c=13997(6)A, α=10387(3)°, β=10698(3)° and γ=10510(2)°; z=2 In this dinuclear molecule both Rh atoms have a square planar coordination sharing one edge, namely the two sulphur bridging atoms The Rh—Rh separation of 296 A is consistent with at most a very weak metal-metal interaction Upon addition of CO the dimeric [Rh(μ-SR)(CO)2]2 (4), (5) and (6) are obtained, but addition of PPh3 affords the monomeric species [Rh(SR)(PPh3)-(COD)] (7), (8) and (9) Reactions of the dimeric tetracarbonyl derivatives with PPh3 vary with the nature of R; [Rh(μ-SR)(PPh3)(CO)]2 is obtained when R=p-C6H4F (10) and CF3 (11) but monomeric [Rh(SR)-(PPh3)(CO)2] (12) is produced when R=p-C6HF4 The latter mononuclear compounds, with R=p-C6H4F (13) and CF3 (14), are also formed by reaction of [Rh(SR)-(PPh3)(COD)] with CO
TL;DR: In this article, the Schiff base ligand (FBz) was used as a corrosion inhibitor for copper in the presence of fluorenone with S-benzyldithiocarbazate.
Abstract: New CuII, CoII, NiII, CdII, ZnII, HgII, PdII and UO
2
II
complexes of the Schiff base ligand (FBz) formed by condensation of fluorenone withS-benzyldithiocarbazate have been prepared and characterized by elemental analysis, magnetic and spectroscopic measurements. The Cu(FBz)2(Cl)2 complex is paramagnetic. The Ni(FBz-H)2 complex is diamagnetic, four-coordinate and square planar. The CoII ion is oxidized in the presence of the Schiff base with the concomitant formation of CoIII complex of empirical formulae Co(FBz)Cl3OH2. The ligand was tested as a corrosion inhibitor for copper. Inhibition efficiency was calculated and the limiting concentration of FBz to give maximum efficiency was 10−3 mol dm−3 at 25°C. The polarographic reduction of FBz was investigated in Britton-Robinson buffer solutions of pH 3–10. The polarograms at dme indicated that the depolarizer is reduced through two two-electron irreversible diffusion-controlled waves. The mechanistic pathway of the electrode reaction is commensurate with this result.
TL;DR: The effect of axial anion on the thermal behavior of square pyramidal MnIII complexes of [Mn(SB)X] has been studied in this article, where a correlation has been made between the thermal stabilities of the complexes and the electronegativities (ξ) of the axial donor atoms.
Abstract: The effect of the axial anion on the thermal behaviour of square pyramidal MnIII complexes of [Mn(SB)X] (where SB=tetradentate dibasic Schiff base; X=OAc−, SCN−, Cl−, Br− or I−) has been studied. A correlation has been made between the thermal stabilities of the complexes and the electronegativities (ξ) of the axial donor atoms. Other solid state phenomena (nature of interaction of the solvent of crystallization and polymorphic transformation) were also studied for the acetato and isothiocyanato complexes.
TL;DR: In this article, the rate laws for the two cases also differ: Equations 1 and 2K1 is the equilibrium constant of formation of the OsVIII-allyl alcohol complex and k 1 is the rate constant of its oxidation by CeIV; K2 is the optimum rate for the formation of a CeIV-PdII-al- alcohol complex, and k2 is its rate constant for decomposition.
Abstract: Catalysis of the CeIV-allyl alcohol (AA) reaction in acid solution depends both on the of rate enhancement and product distribution on the catalyst used: OsVIII results mainly in acrolein, whereas PdII gives acrylic acid. The rate laws in the two cases also differ:viz., Equations 1 and 2K1 is the equilibrium constant of formation of the OsVIII-allyl alcohol complex and k1 is the rate constant of its oxidation by CeIV; K2 is the equilibrium constant for the formation of the CeIV-PdII-allyl alcohol complex and k2 is its rate constant of decomposition. Rate = K1k1[CeIV][AA][OsVIII]/(1+K1[AA]) (1) Rate = K1k1[CeIV][PdII]/(1+K2[CeIV]) (2)
TL;DR: In this paper, the kinetics of the reaction between the protonated forms of [MoO2(CN)4]4− and 2,2′-bipyridyl (bpy) have been studied in the 8.5-11.7 pH range.
Abstract: The kinetics of the reaction between the protonated forms of [MoO2(CN)4]4− and 2,2′-bipyridyl (bpy) have been studied in the 8.5–11.7 pH range. This study showed that the diprotonated form, [MoO(OH2)(CN)4]2− is the only reactive species. The rate-limiting step is the substitution of the aqua ligand. This is followed by fast closure of the chelate ring, accompanied by the substitution of a cyanide ligand. With excess bpy the relatively slow formation of an adduct occurs. The nature of this adduct is discussed.
TL;DR: In this article, the tetradentate Schiff-base ligand N, N€-bis(salicylidene)-o-phenylenediamine (salph) is very strongly sorbed by cation exchange materials with transition metal counter ions, forming stable complexes.
Abstract: The tetradentate Schiff-base ligandN, N
′-bis(salicylidene)-o-phenylenediamine (salph) is very strongly sorbed by cation exchange materials with transition metal counter ions, forming stable complexes. The kinetics of catalytic decomposition of H2O2 in the presence of (salph)-FeIII sorbed on Dowex-50W resin has been studied in aqueous medium. The reaction is first order with respect to [H2O2]. The rate constant, k (per g of dry resin) decreased with increasing degree of resin cross-linkage due to a salting out effect. The activation parameters were calculated and a reaction mechanism is proposed.
TL;DR: In this article, mixed-ligand nickel(II) complexes having octahedral stereochemistry and general formula [Ni-(acac)2(L)2]/[Ni(meacac),2(H2O)2], with L in alcohol have been isolated by reacting [Ni(acac, 2(H 2O) 2] with L 2 in alcohol, where L = 3-methyl-1-phenyl-2-pyrazoline-5-one.
Abstract: Novel mixed-ligand nickel(II) complexes having octahedral stereochemistry and general formula [Ni-(acac)2(L)2]/[Ni(meacac)2(L)2]/[Ni(etacac)2(L)2] (where L=3-methyl-1-phenyl-2-pyrazoline-5-one, 2,3-dimethyl-4-methylaminomethanesulphonate sodium monohydrate-1-phenyl-3-pyrazoline-5-one or 4-amino-2,3-dimethyl-1-phenyl-3-pyrazoline-5-one) have been isolated by reacting [Ni(acac)2(H2O)2]/[Ni(meacac)2(H2O)2]/ [Ni(etacac)2(H2O)2] with L in alcohol. The derivatives have been characterized by analytical data, molar conductances, magnetic measurements, electronic and i.r. spectra.
TL;DR: In this paper, a review of the years 1987-mid 1990 covers the years of homogeneous catlysis of carbonylation reactions, some mechanistic advances which are specially relevant to the developpment of new synthetic methodologies.
Abstract: Thie review covers the years 1987-mid 1990. Synthetic aspects referring to homogeneous catlysis of carbonylation reactions, some mechanistic advances which are specially relevant to the developpment of new synthetic methodologies. Bibliography
TL;DR: In this article, a dissociative mechanism is proposed for the substitution reactions between [ReO(H2O)(CN)4]− and the monodentate nucleophiles.
Abstract: The kinetics of the substitution reactions of the protonated froms oftrans-tetracyanodioxorthenate(V) with thiourea (TU),N-methylthiourea (NMTU),N, N′-dimethylthiourea (NNDMTU) and hydrazoic acid (HN3) were studied. The results were compared with those obtained for similar reactions of [WO2(CN)4]4−. This study showed that the diprotonated form [ReO(H2O)(CN)4]− is the only species reactive towards substitution reactions (and not the [ReO(OH)(CN)4]2− ion) and that only the aqua ligand in [ReO(H2O)(CN)4]− is substituted by the incoming group. A dissociative mechanism is proposed for the substitution reactions between [ReO(H2O)(CN)4]− and the monodentate nucleophiles. The i.r. data for these Rev complexes are reported and discussed in terms of the relativetrans influence of the various monodentate ligands.
TL;DR: In this article, the RuO4-catalysed oxidation of cyclopentanol (Cypol) and cyclohexanol (Cyhol) in alkaline KBrO3 in the presence of Hg(OAc)2 which acts as a bromide ion scavenger has been made in the 30°-45°C range.
Abstract: Kinetic investigations on the RuO4-catalysed oxidation of cyclopentanol (Cypol) and cyclohexanol (Cyhol) in alkaline KBrO3 in the presence of Hg(OAc)2 which acts as a bromide ion scavenger have been made in the 30°–45°C range. The reaction exhibits zero order kinetics in OH− and is first order with respect to BrO3−, substrate and RuO4. The influence of Hg(OAc)2 and ionic strength is insignificant. A transient complex, formed between HRuO5− (the active species of RuO4) and the cyclic alcohol, reacts with BrO3− in a slow, rate determining step to give the products; the catalyst is regenerated.
TL;DR: In this article, the semiquione ligand is oxidized by dibenzoyl disulphide to 9,10-phenanthrenequinone and the complex [(PPh3]Cu(μ-PhCOS)2 Cu(PPh 3)2] (3) is formed.
Abstract: In 9,10-phenanthrenesemiquinonatobis(triphenylphosphine)copper(I) (1) the semiquione ligand is oxidized by dibenzoyl disulphide to 9,10-phenanthrenequinone and the complex [(PPh3)Cu(μ-PhCOS)2 Cu(PPh3)2] (3) is formed. Crystals of the complex are triclinic, space group\(P\bar 1\), with cell parametersa=10.712(1),b=12.887(1).c=22.064 A, α=78.29(1), β=81.88(1), γ=80.83(1), and Z=2. The copper atoms are bridged by the sulphur atoms of the two thiobenzoate groups to form binuclear molecules. The Cu2S2 rhombus is strictly co-planar (Cu−S distances from 2.309 to 2.424 A). The trigonal planar co-ordination around the one and the tetrahedral coordination around the other copper atom are completed by the phosphorus atoms of the triphenylphosphine molecules (Cu−P distances from 2.238 to 2.287 A). The copper-copper distance (Cu−Cu=2.620 A) is 0.6 A longer than that in metallic copper.