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According to the NMR spectroscopic data, the oxidation of triphenylantimony with 4-hydroperoxy-2-hydroxy-3,4,6-triisopropylcyclohexa-2,5-dienone involves three steps. The first step affords the 2,4,10,12-tetraoxa-3,11-distibatricyclo[11.3.1.15,9]octadecatetraene derivative. The latter is rearranged into benzodioxastibolone derivatives followed by the rearrangement into 4,6,7-triisopropyl-2,2,2-triphenyl-1,3,2-benzodioxastibol-5-ol. The transformation of the latter depends on the presence of oxygen and the mode of its dosing.

The interaction of 9,10‐phenanthrenquinone with primary amines has been studied. Use of sterically hindered anilines gave the phenanthren‐o‐iminoquinones in good yields. These compounds are structural analogues of o‐benzoquinones. Using single‐electron reduction, o‐iminoquinones may synthesize metal's free‐radical complexes.

Lead(II) catecholate complexes were prepared by reduction of 3,6-di-tert-butyl-o-benzoquinone and its derivatives with lead metal in THF. The molecular structure of the (CatPb)4·(PbO)2·6C3H6O complex (Cat is the dianion of 3,6-di-tert-butylcatechol), which was synthesized by hydrolysis of lead 3,6-di-tert-butylcatecholate in acetone, was established by X-ray diffraction. A series of lead(II) o-semiquinone complexes, which were prepared by the addition of the phenoxyl radical to lead catecholates or by oxidation of the latter with mercury(II), copper(II), or silver(I) halides, were studied by the ESR method. Lead(II) mono-o-semiquinolate complexes undergo symmetrization to form stable bis-o-semiquinolates, which were isolated and characterized in individual state.

Reactions of 3,6-di(tert-butyl)-o-benzoquinone with primary amines occur by the nucleophilic 1,4-addition mechanism and lead to the corresponding 2-hydroxy-p-quinonimines, which exist in solutions in equilibrium with tautomeric 4-amino-o-quinones. The thermodynamic parameters of this prototropic isomerism were determined by NMR spectroscopy. In the case of a secondary amine (piperidine), a derivative of 4-amino-o-quinone was obtained; the corresponding o-semiquinone complexes were studied in solution by ESR spectroscopy.

Novel neutral antimony(V) complexes were isolated as crystalline materials and characterized by IR and NMR spectroscopy: o-amidophenolate complexes [4,6-di-tert-butyl-N-(2,6-dimethylphenyl)-o-amidophenolato]triphenylantimony(V) (Ph3Sb[AP-Me], 1) and [4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-amidophenolato]triphenylantimony(v) (Ph3Sb[AP-iPr], 2); catecholate complexes (3,6-di-tert-butyl-4-methoxycatecholato)triphenylantimony(V) (Ph3Sb[(MeO)Cat], 3), its methanol solvate 3⋅CH3OH (4); (3,6-di-tert-butyl-4,5-di-methoxycatecholato)triphenylantimony(V) (Ph3Sb[(MeO)2Cat], 5) and its acetonitrile solvate 5⋅CH3CN (6). Complexes 1–7 were synthesized by oxidative addition of the corresponding o-iminobenzoquinones or o-benzoquinones to Ph3Sb. In the case of the phenanthrene-9,10-diolate (PhenCat) ligand, two different complexes were isolated: Ph3Sb[PhenCat] (7) and [Ph4Sb]+[Ph2Sb(PhenCat)2]− (8). Complexes 7 and 8 were found to be in equilibrium in solution. Molecular structures of 2, 4, 6, and 8 were determined by X-ray crystallography. Complexes 1–7 reversibly bind molecular oxygen to yield Ph3Sb[L-Me]O2 (9), Ph3Sb[L-iPr]O2 (10), Ph3Sb[(MeO)L′]O2 (11), Ph3Sb[(MeO)2L′]O2 (12) and Ph3Sb[PhenL′]O2 (13), which contain five-membered trioxastibolane species (where L is the O,O′,N-coordinated derivative of a 1-hydroperoxy-6-(N-aryl)-iminocyclohexa-2,4-dienol, and L′ the O,O′,O′′-coordinated derivative of 6-hydroperoxy-6-hydroxycyclohexa-2,4-dienone). Complexes 9–13 were characterized by IR and 1H NMR spectroscopy and X-ray crystallography.

The reduction of 3,6-di-tert-butyl-o-benzoquinone with tin amalgam gives the different tin catecholate complexes. The use of polar solvents for this reaction leads to the formation of Cat2Sn · L2 species (where Cat—dianion of 3,6-di-tert-butylcatechol, L = Et2O, THF, Py). The reaction carried out in toluene produces the mixture of dicatecholate tin(IV) and catecholate tin(II) derivatives. The complex Cat2Sn · (Et2O)2 was shown to be a good starting reagent for the preparation of different tin(IV) catecholate complexes of the type Cat2Sn · L′ (L′ = 1,2-dimethoxyethane, 1,4-di-tert-butyldiazadiene-1,3, o-phenantrolyne, α,α′-dipyridyl) using ligand exchange reactions. Compounds Cat2Sn · (Et2O)2, Cat2Sn · (THF)2, Cat2Sn · (ButNCHCHNBut), and (CatSn)3 have been crystallographically characterized. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:481–490, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20271

New five-coordinate complexes Co(ISQ-Pri)2Cl, Co(ISQ-Me)2Cl, Co(ISQ-Me)2I, Co(ISQ-Me)2(SCN), Mn(ISQ-Pri)2Cl, and Fe(ISQ-Me)2Br (ISQ-Pri and ISQ-Me are the 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-and 4,6-di-tert-butyl-N-(2,6-dimethylphenyl)-o-iminobenzosemiquinone radical anions, respectively) were synthesized. The complexes were characterized by UV-Vis and IR spectroscopy and magnetochemistry. The molecular structures of the Fe(ISQ-Me)2Br and Mn(ISQ-Pri)2Cl complexes were established by X-ray diffraction. The singlet ground state (S = 0) of the cobalt complexes is caused by antiferromagnetic coupling between the unpaired electrons of the radical ligands (S = 1/2) through the fully occupied atomic orbitals of low-spin cobalt(III) (d6, S = 0). The effective magnetic moments of the complexes at 10 K are 0.18 μB for Co(ISQ-Pri)2Cl and 0.16 μB for Co(ISQ-Me)2I. The ground state of the manganese complex is triplet (S = 1). Two unpaired electrons of the o-iminobenzosemiquinone ligands are strongly antiferromagnetically coupled with two of four unpaired electrons of high-spin manganese(III) (d4, S = 2).

Cyclization of substituted quinone imines and diazabutadiene derivatives of aminophenols affords 4aH-phenoxazine or 4H-1,4-benzoxazine derivatives, which are finally transformed into the following fused heterocycles: the stable 1,4,6,8-tetra(tert-butyl)phenoxazin-10-yl radical and 7a,14a,15a, 15b-tetrahydro-14,16-dioxa-5,9-diaza-8,15-ethenohexaphene and 5a,6,11a, 12-tetrahydro[1,4]benzoxazino[3,2-b][1,4]benzoxazine derivatives. The influence of the substituents on the pathways of the reactions of intermediate benzoxazines and phenoxazines, such as oxidation, [2+4] dimerization, and the closure of the second ring, was studied. The structures of the fused heterocycles were determined by X-ray diffraction, NMR spectroscopy, and ESR.

Four-coordinate complex MnIII(ISQ-Pri)(AP-Pri) (1), where ISQ-Pri = 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzosemiquinonate anion-radical, AP-Pri = 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-amidophenolate dianion, has been prepared by the reaction of Mn2(CO)10 with free 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzoquinone (IBQ-Pri) in the molar ratio 1:4 in toluene. In contrast to manganese, rhenium carbonyl reacts with o-iminobenzoquinone to form complex ReII(ISQ-Pri)2(CO)2 (2) with the retention of two carbonyls in coordination sphere of rhenium. The complexes have been characterized by IR, UV–Vis, and EPR spectroscopies. Molecular structures of compounds 1 and 2 have been determined by single-crystal X-ray crystallography. Compound 1 is centro-symmetric square-planar molecule with delocalized mixed valent state of AP-Pri and ISQ-Pri ligands. EPR spectrum of 1 in solid at 300–77 K is typical for manganese complexes with S = 3/2 state. The effective magnetic moment of 1 is 1.96 μB at temperature 5 K as it was established by variable-temperature magnetic susceptibility measurements. Six-coordinate octahedral complex 2 possesses an S = 1/2 ground state, which is attained via strong intramolecular antiferromagnetic interaction between t2g orbital unpaired electron of the low spin ReII ion and the unpaired electron on π-orbital of the radical ligand.

New catecholate Sb(V) complexes triphenyl(3,6-di-tert-butylcatecholato)antimony(V) Ph3Sb(3,6-DBCat) (1) and triphenyl(perchloroxanthrenecatecholato)antimony(V) Ph3Sb(OXCatCl) (2) were synthesized by the oxidative addition reaction of corresponding o-quinones (3,6-di-tert-butyl-o-benzoquinone and perchloroxanthrenequinone-2,3) with triphenylantimony. Catecholates 1 and 2 can alternatively be synthesized by reacting the appropriate thallium catecholate with triphenylantimony dichloride. The oxidative addition reaction of an equimolar ratio of 4,4′-di-(3-methyl-6-tert-butyl-o-benzoquinone) and triphenylantimony yielded 4-(2-methyl-5-tert-butyl-cyclohexadien-1,5-dion-3,4-yl)-(3-methyl-6-tert-butyl-catecholato)triphenylantimony(V) Ph3Sb(Cat-Q) (3); in the case of a 1:2 molar ratio, complex 4,4′-di-[(3-methyl-6-tert-butyl-catecholato)triphenylantimony(V)] Ph3Sb(Cat-Cat)SbPh3 (4) resulted. Complexes 1–4 were characterized by IR- and 1H NMR spectroscopy. Molecular structures of 1, 2 and 4 were determined by X-ray crystallography to be a distorted tetragonal-pyramidal.

New square planar CoII(ISQ-iPr)2 (1), CoII(ISQ-Me)2 (2) and five-coordinate CoIII(ISQ-Me)2Cl cobalt complexes (3) (ISQ-iPr=4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzosemiquinonate radical-anion, ISQ-Me=4,6-di-tert-butyl-N-(2,6-di-methylphenyl)-o-iminobenzosemiquinonate radical-anion) have been prepared using different methods. Complexes 1–3 have been characterized by IR, UV–Vis, EPR spectroscopy. Molecular structures of 1 and 3 were determined using X-ray crystallography. It has been established from variable-temperature magnetic susceptibility measurements and X-band EPR spectroscopy that 1 and 2 possess an S=1/2 ground state. In the complex molecules the unpaired electrons of o-iminobenzosemiquinonate radical ligands (Srad=1/2) are strongly coupled antiferromagnetically. The sterical hindrances of N-aryl in o-iminobenzosemiquinonate ligands prevent the formation of a hexacoordinate species.

[4,6-Di-tert-butyl-N-(2,6-diisopropylphenyl)-o-iminobenzosemiquinonato]thallium(i) was synthesized and characterized by IR and ESR spectroscopy. The hyperfine coupling constants with 203/205Tl nuclei were found to depend strongly on the nature (solvating ability) of solvents. At 298 K, the HFC constant aTl changes from 3.09 mT in n-hexane up to 19.70 mT in tetramethylethylenediamine. The coordination number of solvation was found to be 1 for DMF—benzene and pyridine—hexane systems. The thermodynamic characteristics of solvation in the pyridine—hexane system were determined.

A new semiquinone rhodium complex,viz., (2,2′-dipyridyl)(3,6-di-tert-butyl-o-benzosemiquinone)(3,6-di-tert-butylcatecholate)rhodium(III) (1), which is a structural analog of the known redox-isomeric cobalt complex, was prepared, isolated in the individual state, and characterized by X-ray analysis, magnetochemistry, and IR and ESR spectroscopy. At room temperature, compound1, unlike the cobalt analog, is a complex of trivalent low-spin rhodium with one catecholate and one semiquinone ligand. However, broadening of the lines in the ESR spectra both of a solution and a powder of complex1 with increasing temperature indicates that the redox-isomeric transformation occurs in this case as well. The equilibrium of this transformation is virtually completely shifted toward the low-spin semiquinone-, catecholate isomer.

Reaction of 3,6-di-tert-butyl-1,2-benzoquinone and 3,6-di-tert-butylcatechol withtert-butyl hydroperoxide in aprotic solvents leads to the generation of semiquinone (SQ.H), alkylperoxy (ROO.), and alkyloxy radicals. The reaction of SQ.H and ROO. produces 2,5-di-tert-butyl-6-hydroxy-1,4-benzoquinone, 3,6-di-tert-butyl-1-oxacyclohepta-3,5-diene-2,7-dione, and 2,5-di-tert-butyl-3,6-dihydroxy-1,4-benzoquinone. The radical generated from solvent attacks SQ.H at position 4 with C−C bond formation. 4-Benzyl-2,5-di-tert-butyl-6-hydroxycyclohexa-2,5-diene-1-dione produced in this way is transformed into 4-benzyl-3,6-di-tert-butyl-1,2-benzoquinone under the reaction conditions.

Reactions of 3,6-di-tert-butyl-1,2-benzoquinone with PhC≡CLi and ButC≡CLi are multistage processes. In the first stage, nucleophilic 1,2-addition of the organometallic compound too-benzoquinone occurs to form the corresponding hydroxycyclohexadienone derivative. In polar solvents, the latter undergoes rearrangement through insertion of the oxygen atom into the ring to form a new allenic organolithium compound. The reaction of the newly formed organometallic compound with the initialo-quinone occurs either as a one-electron transfer to yield lithium semiquinolate and a dimerization product,viz., 4,4′-bi(2,5-di-tert-butyl-9,9-dimethyldeca-2,5-dien-7-yn-1,6-olide), or as the 1,4-addition to yield 2,5-di-tert-butyl-8-(3,6-di-tert-butyl-1,2-benzoquinon-4-yl)-8-phenylocta-2,4,6,7-tetraen-1,6-olide. The structure of the latter compound was established by X-ray diffraction analysis and by NMR and IR spectroscopy.

New di-o-quinones of the biphenyl series, namely, 2,2′-dialkyl-5,5′-di-tert-butylbiphenyl-3,4,3′,4′-diquinones, were synthesized. Their structures were established by IR and NMR spectroscopy. The molecular structure of 2,2′-dimethyl-5,5′-di-tert-butylbiphenyl-3,4,3′,4′-diquinone was established by X-ray structural analysis. The structure is characterized by orthogonal (the torsion angle is 82.9°) mutual arrangement ofo-benzoquinone fragments. ESR studies demonstrated that chemical reduction of diquinone proceeds in four oneelectron stages to form paramagnetic mono- and trianions as intermediates. Quinopyrocatechols, which are intermediates in the synthesis of di-o-quinones, were isolated and characterized.

Base-catalyzed interaction of 3,6-di-tert-butyl-1,2-benzoquinone with malononitrile mainly occurs as 1,4-addition to give 3,6-di-tert-butyl-4-dicyanomethylpyrocatechol. Its oxidation leads to 3,6-di-tert-butyl-4-dicyanomethyl-1,2-benzoquinone, which converts into 3,6-di-tert-butyl-2-hydroxy-α,α-dicyano-1,4-quinomethane in solution and in the solid state. The latter rearranges into isomeric 3,6-di-tert-butyl-5-dicyanomethylenecyclohex-3-ene-1,2-dione. Reverse conversion occurs under the action of amines. Semiquinone complexes of dicyanomethylquinone were studied in solutions by ESR.

Stable molecular complexes of bis[tris(trifluoromethyl)germyl]mercury(II) Hg[(CF3)3Ge]2 (1) witho-quinones (3,6-di-tert-butylbenzoquinone-1,2 (2), 3,6-di-tert-butyl-4,5-dimethoxybenzoquinone-1,2 (3), and 1,4,5,7-tetra-tert-butyldibenzo[1,4]dioxin-2,3-dione (4)) have been synthesized and characterized by elemental analysis and IR and electronic absorption spectroscopies. Depending on the ratio between the starting reactants, the reactions ofo-quinones with1 gave complexes of the composition R2Hg · Q (5,7,9) or R2Hg · Q2 (6,8,10), where Q=2 (5,6),3 (7,8),4 (9,10); R=Ge(CF3)3. According to the spectral data, the molecule ofo-quinone in R2Hg · Q acts as a neutral ligand, whereas the second molecule ofo-quinone in R2Hg · Q2 is not coordinated to1. It has been found by ESR that thermolysis of polycrystalline samples of complexes6 and10 involves intermediate formation of radical pairs and finally yields paramagnetico-semiquinone complexes, SQGe(CF3)3, which are typical products of one-electron oxidation of Organometallic compounds byo-quinones.

3,6-Di- tert -butyl- o -benzosemiquinone is very convenient for the investigation of the interaction between organometallic R 2 M and carbonyl compounds. The reaction of organometallic compounds R 2 M with o-quinone, where R = Ph, Me, Et, Pr, 1 Pr or t Bu and M ≡ Zn, Cd, and Al, proceeds in two ways: (1) the single-electron oxidation of the organometallic compound by o -quinone, resulting in derivatives of alkyl(phenyl)oxyphenols; (2) the polar 1,2 and 1,4 addition of organometallic molecules to o -quinone as to conjugated ketone, which produces hydroxycyclohexadienones after hydrolysis. The relationship between these two is defined by the nature of the organometallic compound. The products of polar addition are rearranged easily in different ways, finally resulting in new o-quinones: 3-(R)-6- tert -butyl- o -benzoquinones and 3,6-di- tert -butyl-4-(R)- o -benzoquinones where R ≡ alkyl.

New fluorine- containing 3,6-di-tert-butyl-o-benzoquinones have been synthesized. In the EPR spectra the19F hyper fine coupling constant of the corresponding semiquinones was shown to be highly dependent on the metal, its surrounding ligand, and the solvent.

2-(Triphenylstannyloxy)-3,6-di-tert-butyl-1,4-benzoquinone (1) was obtained from the potassium salt of 3,6-di-tert-butyl-2-hydroxy-1,4-benzoquinone and triphenyltin bromide in methanol and characterized by x-ray diffraction analysis, electronic, IR, and NMR spectroscopy. According to x-ray diffraction data, the single crystal of1 has the structure of a chain metal polymer with bridging hydroxy-para-quinone ligands; the coordination number of tin is six. Complex1 is reduced by cobaltocene to the corresponding radical anion. In solutions,1 reacts with metal-centered radicals\(\dot SnPh_3 , \dot PbPh_3 \), and\(\dot Mn(CO)_5 \) with formation of paramagnetic binuclearortho-semiquinone complexes.

Reactions of 3,6-di-tert-butyl-1,2-benzoquinone with PhC≡CLi and ButC≡CLi are multistage processes. In the first stage, nucleophilic 1,2-addition of the organometallic compound too-benzoquinone occurs to form the corresponding hydroxycyclohexadienone derivative. In polar solvents, the latter undergoes rearrangement through insertion of the oxygen atom into the ring to form a new allenic organolithium compound. The reaction of the newly formed organometallic compound with the initialo-quinone occurs either as a one-electron transfer to yield lithium semiquinolate and a dimerization product,viz., 4,4′-bi(2,5-di-tert-butyl-9,9-dimethyldeca-2,5-dien-7-yn-1,6-olide), or as the 1,4-addition to yield 2,5-di-tert-butyl-8-(3,6-di-tert-butyl-1,2-benzoquinon-4-yl)-8-phenylocta-2,4,6,7-tetraen-1,6-olide. The structure of the latter compound was established by X-ray diffraction analysis and by NMR and IR spectroscopy.

2-(Triphenylstannyloxy)-3,6-di-tert-butyl-1,4-benzoquinone (1) was obtained from the potassium salt of 3,6-di-tert-butyl-2-hydroxy-1,4-benzoquinone and triphenyltin bromide in methanol and characterized by x-ray diffraction analysis, electronic, IR, and NMR spectroscopy. According to x-ray diffraction data, the single crystal of1 has the structure of a chain metal polymer with bridging hydroxy-para-quinone ligands; the coordination number of tin is six. Complex1 is reduced by cobaltocene to the corresponding radical anion. In solutions,1 reacts with metal-centered radicals\(\dot SnPh_3 , \dot PbPh_3 \), and\(\dot Mn(CO)_5 \) with formation of paramagnetic binuclearortho-semiquinone complexes.

New sterically hindered functionalized o-quinones were synthesized by the 1,4-nucleophilic addition of secondary cyclic amines to 3,6-di(tert-butyl)-o-benzoquinone. The ability of these o-quinones to form o-semiquinone complexes with transition and main-group metals was studied by ESR spectroscopy in solution.

The interaction of 9,10‐phenanthrenquinone with primary amines has been studied. Use of sterically hindered anilines gave the phenanthren‐o‐iminoquinones in good yields. These compounds are structural analogues of o‐benzoquinones. Using single‐electron reduction, o‐iminoquinones may synthesize metal's free‐radical complexes.

The reaction of 3,6-di-tert-butyl-o-benzoquinone with dimedone in the presence of a catalytic amount of Et3N occurs as repeated 1,4-nucleophilic addition-oxidation and isomerization of a tricyclic quinone into quinomethane. The intermediate products were isolated and characterized. Semiquinone complexes of quinones were studied by ESR in solution.

Thermodecomposition of 3,5- and 3,6-di-tert-butyl-o-benzoquinone complexes of Cu, Fe, Co, Cr, Mo, and W has been investigated in the solid phase by the thermogravimetric method. The relative stability of a series of complexes has been determined from the temperatures at which their decomposition begins. Detachment of a neutral electron-donor ligand takes place in the first stage. Detachment of ano-quinone ligand and decomposition of theo-benzoquinone formed occur in the next stage. Thermodecomposition of Fe, Co, Cr, Mo, and W complexes gives oxides or carbides, while copper complexes decompose to pure metal.

New fluorine- containing 3,6-di-tert-butyl-o-benzoquinones have been synthesized. In the EPR spectra the19F hyper fine coupling constant of the corresponding semiquinones was shown to be highly dependent on the metal, its surrounding ligand, and the solvent.

It was established that photodecarbonylation of o-benzoquinones occurs by irradiation not only by UV-light, but visible light (λ>520 nm) too. Study of the series of 4,5-di-substituted 3,6-di-tert-butyl-o-benzoquinones detected that the only product of photoreaction is the corresponding 3,4-di-substituted 2,5-di-tert-butyl-cyclopentadienone, which is formed in a yield close to quantitative. NMR monitoring of reaction of photodecarbonylation of o-benzoquinones detected that this is a two-stage process. In the first stage the photoexcited molecule of quinone rearranges into bicyclo compound (bicyclo[1.3.0]hexa-3-en-2,6-dione) containing five- and three- membered cycles, which spontaneously decomposes during the following dark stage into cyclopentadienone and a molecule of CO.

1. New stable paramagnetic o-semiquinolates of palladium and platinum with arylazoaryl ligands have been synthesized. 2. The reactions of the o-semiquinolato complexes of palladium and platinum with triphenylphosphine proceed differently and result, in the case of palladium, in the cleavage of the Pd ← N coordinate bond and the preservation of the o-semiquinolate structure of the original complex, and, in the case of platinum, displacement of the azo ligand and the formation of a pyrocatecholate derivative of platinum are observed.

1. A new method was proposed for obtaining the o-semiquinolate complexes of the transition metals, which consists of reacting the salts of the acids of the metals, or of their halides, with substituted pyrocatechols in the presence of a base and atmospheric oxygen. 2. It was shown that oxidation-reduction transitions can take place between the pyrocatechol and o-semiquinolate complexes.

The reaction between salts of transition metal sandwich cations and β-diketones (HCh) has been investigated using allyl, cyclopentadienyl and arene derivatives of Fe, Pd, Cr, Ti as sandwich components, and with acetylacetone (HA), dibenzoylmethane (HD), thenoyltrifluoroacetone (HT), ferrocenoyltrifluoroacetone (Ho) as chelating components. The sequence of bond stabilities in bis-aromatic iron complexes has been established as Ch-Fe > Cp-Fe > Arene-Fe whilst in allyl complexes the corresponding sequence has been shown to be Ch-Fe > All-Fe > CO-Fe. Disproportionation products of mixed sandwich chelate complexes containing one hydrocarbon ligand have been isolated. The corresponding influence of hydrocarbon ligands and of the chelate in mixed complexes as indicated by IR and electronic spectra are discussed as are the possible changes in bond character which occur in these complexes.

1. Perchloro-2,3-oxanthrenequinone was synthesized for the first time. 2. The advantages of using perchloro-2,3-oxanthrenequinone as a model acceptor when studying the structure of chelate complexes by the EPR method were shown.

1. A study of the chlorination of 3,6-di-tert-butylpyrocatechol and its corresponding quinone and 4-chloro-3,6-di-tert-butyl-o-benzoquinone by sulfuryl chloride showed that this method may serve as a preparative method for obtaining 4-chloro-3,6-di-tert-butyl-o-benzoquinone and 4,5-dichloro-3,6-di-tert-butyl-o-benzoquinone. 2. A mechanism was established for the reaction of 4-X-3,6-di-tert-butyl-o-benzoquinone (X=H, Cl) with SO2Cl2 involving the protonation of SO2Cl2.

A preparation is reported for o-benzoquinones and catechols containing tertiary alkyl substituents in the ortho position.

Mixed paramagnetic cobalt dinitrosyl o-semiquinone complexes were obtained for the first time in solution. IR and EPR spectroscopy showed that these complexes have distorted tetrahedral structure, while their ground electronic state is [Co(NO)2]10 with the unpaired electron on the o-semiquinone ligand.

1. We synthesized a number of p-substituted 1-aryl-3-tert-butyl-3-hydroxytriazenes. Their oxidation with lead peroxide leads to cleavage, with the formation of aryl radicals, nitrogen and 2-nitroso-2-methylpropane. 2. The EPR spectrum of p-nitrophenyl-tert-butyl nitroxide was obtained, which differs from that described previously in the literature. An interpretation of the spectrum is given.

Bei der Behandlung von 3,6-Di-tert.-butyl-brenzcatechin (I) mit Sulfurylchlorid entsteht uber die Stufe des bereits fruher beschriebenen o-Benzochinons (II) das Dichlorcyclohexendion (III).