Phenoxide Oxygen Research Articles

Dimeric mixed-ligand copper(II) complexes with di-imines and salicylaldehydate

The variable-temperature (2–298 K) magnetic susceptibility, electrochemical, and spectral properties of three binuclear copper(II) complexes [{CuL(sal)}2][ClO4]2 are reported. Each copper(II) ion of the binuclear complex is co-ordinated to a di-imine molecule L [bis(2- pyridyl)amine, 2,2′-bipyridine, or 1,10-phenanthroline], and a salicylaldehydate anion (sal) bridging the two metal ions through the phenoxide oxygen atom. At room temperature the complexes show a normal magnetic moment, µ= 1.8–1.9. However, antiferromagnetic interactions are found when susceptibility data are taken at temperatures down to ca. 2 K. Magnetic, electrochemical, and spectral properties are discussed in relation to the known solid-state geometry of the complexes.

Complexes of 15-crown-5 and cyclohexano-15-crown-5 with lithium, sodium, and potassium phenoxide having macrocycle: salt ratios of 1:1 and 1:2. The crystal structures of two polymorphs of 15-crown-5•2LiOPh

The syntheses, in ethereal solvents, of the complexes of 15-crown-5 and cyclohexano-15-crown-5 with lithium, sodium, and potassium phenoxide are described. The two macrocycles form complexes with lithium and sodium phenoxide with host:guest ratios of 1:2. Potassium phenoxide, however, was complexed by the two macrocycles to give products with macrocycle:salt ratios of 1:1. Crystals of 15-crown-5•2LiOPh were obtained for X-ray diffraction structure determinations. In fact, the crystal structures of two co-crystallizing polymorphs of this complex (1a and 1b) have been determined. Polymorph 1a crystallizes in space group [Formula: see text] with a = 11.386(4), b = 11.901(4), c = 10.654(4) Å, α = 106.53(3), β = 112.60(3), γ = 106.52(3)°, and Z = 2. Polymorph 1b crystallizes in space group P21/n with a = 15.355(4), b = 11.642(2), c = 13.595(6) Å, β = 104.56(3)°, and Z = 4. Both structures were solved by direct methods, and refined by full-matrix least-squares calculations to residuals, R, of 0.053 and 0.055 for polymorphs 1a and 1b, respectively. The structures of the two polymorphs differ only in the orientation of the phenoxides. The structures show a dimer, (15-crown-5•2LiOPh)2, which consists of an aggregate of four lithium phenoxide molecules complexed by two 15-crown-5 macrocycles. The two lithiums of each monomeric unit of this dimer have different crystallographic and chemical environments. One lithium is coordinated to all five oxygens of the macrocycle and to one of the phenoxide oxygens while the other lithium is coordinated to only one oxygen of the macrocycle and to three phenoxide oxygens.

Determining Factors for the Product Para/Ortho Ratio and Reaction Rate in the Formation of (Hydroxymethyl)phenols from Phenol and Formaldehyde

Abstract Formations of 2- and 4-(hydroxymethyl)phenols from phenol and formaldehyde in aqueous alkaline solutions were kinetically investigated by the use of HPLC. The para/ortho ratio for the products sigmoidally increased with increasing concentration of sodium hydroxide, whereas the total yield of the (hydroxymethyl)phenols showed a steep maximum at the charged molar ratio unity of sodium hydroxide to phenol. Use of lithium hydroxide and potassium hydroxide, in place of sodium hydroxide, as alkaline catalysts results in almost the same para/ortho ratios. The addition of potassium chloride and magnesium sulfate decreased both the para/ortho ratio and the yield. These results indicate that the reactions proceed via an electrophilic attack of formaldehyde, which is free from the adduct formation with hydroxide ion, at phenolate ion. Electrostatic interactions between the phenoxide oxygen atom of the phenol and the incoming hydroxymethyl residues in the transition state exhibit a predominant role in the determination of the para/ortho ratio.

The crystal structures of the 1:1:1 complexes of dicyclohexano-18-crown-6 (isomer B) with potassium phenoxide and phenol and dicyclohexano-18-crown-6 (isomer A) with sodium phenoxide and phenol

The crystal structures of the 1:1:1 complexes of dicyclohexano-18-crown-6 (isomer B) with potassium phenoxide and phenol, and of dicyclohexano-18-crown-6 (isomer A) with sodium phenoxide and phenol have been determined. The potassium phenoxide complex crystallizes in space group Pnca with a = 14.150(3), b = 23.794(6), c = 9.491(1) Å, and Z = 4. Thesodium phenoxide complex crystallizes in space group Pbca with a = 21.201(4), b = 24.406(6), c = 12.492(3) Å, and Z = 8. Both structures were solved by direct methods and refined by full matrix least-squares calculations to residuals, R, of 0.059 for the potassium phenoxide complex, and 0.069 for the sodium phenoxide complex. In the potassium phenoxide complex, the cation sits on a centre of symmetry, in the centre of the cavity formed by the crown ether in its regular conformation. The potassium is coordinated to all six crown oxygens as well as to two phenol/phenoxides, one on each side of the crown. Groups of phenol/phenoxide–potassium–phenol/phenoxide are linked by the hydrogen atoms to form a chain: K+… O … H … O … K+. The distance between the oxygens of the phenol/phenoxides is short, 2.48(1) Å. The hydrogen was initially located halfway between the two oxygens, on a 2-fold axis special position. Inspection of the difference Fourier map and refinement on the hydrogen position revealed, however, the presence of statistical or dynamical disordering. In the sodium phenoxide complex, the hexaether adopts an irregular conformation. The distances between the sodium and the crown oxygens range from 2.45 to 2.89 Å, while a distance of 2.363 Å is found with the phenoxide oxygen. Strong hydrogen bonding is found between the oxygens of the phenol and phenoxide. The O ….O distance is 2.471(4) Å.

Synthesis and crystal structure of ammonium (picrate) (dibenzo-18-crown-6)

NH4(Pic)(DB18C6) (Pic=picrate and DB18C6=dibenzo-18-crown-6), (C26H30N4O13) FW 606.56, arthorhombic,Pmn21,a=26.045(5),b=12.055(3),c=8.982(3) A,V=2820(1) A3,Z=4,D c =1.429 g/cm3, CuKα, λ=1.54184 A, μ(CuKα)=9.5 cm−1,F(000)=1272,T=298 K. The structure has been refined toR=0.0475 for 2617 unique observed reflections. In the lattice the 1:1 complex exists as a 2:2 dimer in which the crown are coupled through the Pic anions and NH4 + cations. The asymmetric unit consists of two independent half crown ethers of which two opposite O atoms are on the mirror plane, two half ammonium cations of which the N and two H atoms are also on the mirror plane while the Pic anion is in a general position. Relative to each other, the corwn ethers are shifted by about 7.3 A alongb and 1 A alongc. The 1:1 sandwich of NH4 with DB18C6 and Pic on dimerisation becomes a ‘club pseudo-sandwich’ with three phenyl rings on either side of the mirror plane, thus forming a nearly parallel stack with a 3.6 A inter-ring distance. The NH4 ions hold the structure; two H atoms on the mirror plane are hydrogen-bonded to the opposite oxygens of the crown located on the purely aliphatic part of the ring (2.10(1), 2.06(3) and 2.26(3), 2.05(1) A) for the two independent crowns, respectively, while the other two H atoms form mirror-related bifurcated hydrogen bonds with the phenoxide oxygen (1.99(1) and 2.01(1) A) and theo-nitrogen oxygen (2.44(2) and 2.34(1) A) of the picrates.

The crystal structures of the 1:2 host:guest complexes of dicyclohexano-18-crown-6 (isomers A and B) with sodium and potassium phenoxide

The crystal structures of the 1:2 host:guest complexes of dicyclohexano-18-crown-6 (isomer B) with potassium phenoxide and dicyclohexano-18-crown-6 (isomer A) with sodium phenoxide have been determined. The potassium phenoxide complex crystallizes in space group [Formula: see text] with a = 10.023(2), b = 11.238(2), c = 7.546(2) Å, α = 95.73(2), β = 103.04(2), γ = 92.03(2)°, and Z = 1. The sodium phenoxide complex crystallizes in space group P21/n with a = 19.185(12), b = 13.266(5), c = 13.038(5) Å, β = 96.55(4)°, and Z = 4. Both structures were solved by direct methods and refined by full matrix least-squares calculations to a residual, R, of 0.035. The host conformation as well as the metal cation coordination differ considerably in the two structures. In the potassium phenoxide complex, the two cations are related by symmetry and have, consequently, the same chemical environment. Each potassium is located approximately halfway between the plane formed by the crown ether oxygens and the phenoxide anions and is coordinated to four of the crown oxygens and to two phenoxide oxygens. The oxygens of the crown are found to outline an elliptical cavity and to lie approximately in a plane. In the sodium phenoxide complex, the two sodiums have different crystallographic and chemical environments. One sodium is coordinated to the six hexaether oxygens, with distances ranging from 2.36to2.84 Å, and to one of the phenoxide oxygens. The other sodium is coordinated to only one of the crown oxygens and to three of the phenoxide oxygens. The hexaether adopts a highly irregular conformation.

Derivatives of bivalent germanium, tin, and lead. Part X. Tin(II) bis(phenoxides), bis(O-methyl dithiocarbonate), and bis(diethyidithiocarbamate)

Tin(II) bis(phenoxides), Sn(OR)2(I), have been synthesised in high yield from bis(methylcyclopentadienyl)tin and 2 mol of phenol in benzene or tetrahydrofuran (thf); o-aminophenol yields a compound of composition Sn2(OR)3 due to some Sn–N covalent bond formation. The reaction of Sn(OMe)2 with phenols does not give (I), but [(p-MeC6H4O)SnOSn(OC6H4Me-p)], (IV), has been isolated from the reaction with p-cresol. Mossbauer spectra of the compounds (I) and (IV) indicate the presence of polymeric lattices in which adjacent tin atoms are bridged by oxide and phenoxide oxygen atoms in an infinite array. Tin(II) bis(diethyldithiocarbamate), [Sn(S2CNEt2)2], and bis(O-methyl dithiocarbonate), [Sn(S2COMe)2], have been obtained by metathesis between tin(II) chloride and K[S2CNEt2] or K[S2COMe]. The Mossbauer parameters for the dithiocarbonate are substantially different from those for the diethyldithiocarbamate which is known to possess a structure based on a distorted trigonal bipyramid with the tin lone pair occupying a sp2 hybrid orbital, and suggests a structure in which dithiocarbonate chelates the tin atoms in such a way that the four sulphur atoms are disposed almost tetrahedrally about the metal.

Spiropyrans of the phenanthridine series

The relative stabilities of the cyclic and open forms of spiropyrans of the phenanthridine series depend on the character and position of the substituents in the chromene ring and also on the polarity of the media. The structure of the open forms of the spiropyrans is closer to the limiting dipolar structure. The open forms of the carboxy derivatives of the spiropyrans are stabilized in alcohol solutions due to proton transfer to the phenoxide oxygen.

Thermodynamics of hydration of 3-substituted and 3,5-disubstituted phenols

The enthalpies of transfer of 3-chloro-, 3-nitro-, and 3-t-butyl-phenol and their 3,5-disubstituted analogues from the gas phase to aqueous solution are reported together with the corresponding free energies and entropies of transfer for 3-nitro-, 3,5-dinitro-, 3-t-butyl-, and 3,5-di-t-butyl-phenol. The results support previous conclusions that the entropies of ionization of phenols in water are not solely explicable in terms of the electronic effects of ring substituents on the hydration of phenoxide anions. The hydration of the neutral phenols must also be considered and in some cases becomes the predominant factor influencing the effect of substituents on entropies of ionization. Contrary to current theories the solvent ordering effect of phenoxide anions does not always become weaker if substituents are replaced by other substituents which withdraw electronic charge more strongly from the ring position at which the phenoxide oxygen is sited.

Condensation of 2,4-dinitrochlorobenzene with o-hydroxyarylamides

o-Hydroxyarylamides react readily with 2,4-dinitrochlorobenzene in presence of bases to give the N-2,4-dinitrophenyl derivatives. The reaction appears to proceed by a direct displacement of the halogen by the amide nitrogen involving intramolecular nucleophilic catalysis by the phenoxide oxygen; but a Smiles rearrangement is not completely excluded. The N-dinitrophenyl derivatives are stable to boiling hydrochloric acid, but are hydrolysed easily by aqueous sodium carbonate or hydroxide. Condensation with dinitrochlorobenzene, followed by mild alkaline hydrolysis, is a useful procedure for determining the constitution of azoic coupling components of the Naphtol AS type. Thus Naphtol AS-RS and AS-KN have been shown to be the 4-chloro-2-methoxy-5-methylanilide of 2-hydroxy-3-naphthoic acid and the α-naphthylamide of 3-hydroxydibenzofuran-2-carboxylic acid respectively.