Search

Measurement of the quenching rate constant (kQ) of singlet oxygen (1O2) by α-tocopherol was performed in ethanol solution including four kinds of alkali and alkaline earth metal salts (NaClO4, Mg(C...

(1,3-Dihalo-2-azulenyl)diphenylphosphines 2 [halogen = Cl (a), Br (b)] and homologous bis(1,3-dihalo-2-azulenyl)phenylphosphines 4 have been synthesized, and the effect of the nonalternant azulenyl...

Five kinds of (1:1) and (1:3) salts of 3-(4- and 3-alkyl-pyridinium)-1,5-diphenylverdazyl (alkyl = ethyl and methyl) radical cations with Ni(dmit)2 anion ([p-EtPyDV]+[Ni(dmit)2]− (1), [m-EtPyDV]+[Ni(dmit)2]− (2), [p-MePyDV]+[Ni(dmit)2]− (3), [m-MePyDV]+[Ni(dmit)2]− (4), and [ p - MePyDV ] + [ Ni ( dmit ) 2 ] 3 - ( 5 ) ) (dmit = 1,3-dithiol-2-thione-4,5-dithiolate) have been prepared, and the magnetic susceptibilities (χM’s) have been measured between 1.8 and 300 K. The χM of salt 1 can be well explained by a four-spin linear tetramer model ([p-EtPyDV]+–[Ni(dmit)2]−–[Ni(dmit)2]−–[p-EtPyDV]+) with an end exchange interaction 2J1/kB = −780 K and a central interaction 2J2/kB = −200 K. The formation of magnetic tetramer in salt 1 has been ascertained by the crystal structure analysis of 1. The χM of salt 2 was explained by the sum of the contributions from: (i) a dimer system (2J/kB = −320 K) due to Ni(dmit)2 anions and (ii) the one-dimensional (1D) Heisenberg ferromagnetic linear-chain system (2J kB = +2.5 K) due to verdazyl cations. The χM of salt 3 is similar to that of salt 1, suggesting a formation of magnetic tetramer in salt 3. The χM of salt 4 shows a broad maximum at Tmax = 100 ± 2 K, and can be explained by a 1D Heisenberg antiferromagnetic alternating-chain model with 2J1/kB = −165 K (alternation parameter α = J2/J1 = 0.6). The conductivity (σ) of salts 1, 2, 3 and 4 at 293 K was σ = 2.3 × 10−5, 1.1 × 10−3, 1.4 × 10−5 and 5.4 × 10−6 S cm−1 with an activation energy of EA = 0.28, 0.52, 0.21 and 0.33 eV, respectively. The (1:3) salt 5 (σ = 1.0 S cm−1, EA = 0.048 eV) showed three to five orders of magnitude higher conductivity than those of the (1:1) salts 1–4 at room temperature. All the (1:1) and (1:3) salts 1–5 are new molecular paramagnetic semiconductors.

A nonalternant organyl ligand derived from azulene, a 1,3-dichloro-2-azulenyl group, is introduced for the first time into the bismuth and antimony center. Conversion of the azulenylbismuthanes into the pentacoordinated difluorides by xenon difluoride promotes the π-polarization of the azulene nucleus, which is detected as a color change in solution as well as changes in the chemical shifts of the 13C NMR spectra. A similar tendency is observed in the antimony congeners. The X-ray crystallographic study of (1,3-dichloro-2-azulenyl)diphenylbismuth difluoride (20b) reveals that intermolecular π−π stacking takes place between the azulenyl groups through the interaction of the five-membered ring with the seven-membered ring. This may reflect the more polarized azulenyl group of the difluorides, which strengthens the stacking interaction.

Acid-catalysed hydrolysis kinetics were studied for 14 cobalt(III) carbonato complexes involving the title five at oxonium ion concentration of 0.01-1.0 M, ionic strength of 2.0 (NaClO 4 ) and 15-45°C (M=mol dm m 3 ). Preprotonation constant, about 1 M m 1 , was estimated from a non-linear acidity dependence of an experimental rate constant for the ring-opening of the didentate hydrogencarbonato intermediate. Acidity constant, 0.003-0.7 M, and basicity constant, 0.1-0.9 M m 1 , of the ring-opened aquahydrogencarbonato intermediate were estimated from an acidity dependence of an experimental rate constant for the decarboxylation. Concerning the widely ranging ring-opening rate constants (0.05-126 s m 1 at 25°C), we demonstrate labilizing effects of a reduced charge and of small tetrakis(amine) ligand, correlating with a high activation entropy, as well as of the trans five-membered chelate correlating with a low activation energy. The charge effect may be understood by the solvational change during the dis...

Four kinds of (1:1) and (1:2) salts of 3-(4- and 3-ethyl-pyridinium)-1,5-diphenylverdazyl radical cations with tetracyanoquinodimethanide (TCNQ) anion ([p-EtPyDV]+[TCNQ]− (1), [m-EtPyDV]+[TCNQ]− (2), [p-EtPyDV]+[TCNQ]2− (3), and [m-EtPyDV]+[TCNQ]2− (4)) have been prepared, and the magnetic susceptibilities (χM) measured between 1.8 and 300 K. The values of χMT at 300 K are 0.437, 0.383, 0.620, and 0.482 K emu mol−1 for the salts (1), (2), (3), and (4), respectively, and decrease by lowering the temperature. The χM of the salt (2) follows the Curie–Weiss law with a Curie constant of 0.374 K emu mol−1 and a negative Weiss constant of −2.4±0.2 K in the temperature region 1.8–300 K, indicating disappearance of a net magnetic moment due to the formation of strong spin pairs in TCNQ anion molecules. The χM of the salt (3) shows a broad maximum at T max = 118 ± 2 K and can be well explained by a singlet–triplet equilibrium model with 2 J / k B = - 190 K The χM of the salt (4) shows a broad maximum at T max = 9.3 ± 0.5 K The χM can be well reproduced by the sum of the contributions from: (i) a one-dimensional (1D) Heisenberg antiferromagnetic alternating-chain system with 2 J / k B = - 15.2 K (alternation parameter α=J2/J1=0.4); and (ii) the dimer system with 2 J / k B = - 741 K The magnetic property of (4) was discussed based on the results obtained by crystal structure analysis of (4). On the other hand, the susceptibility of the salt (1) showed anomalous magnetic behavior that cannot be explained by a simple model. The (1:1) salts (1) and (2) are insulators. On the other hand, the pressed pellet conductivity (σ) of the (1:2) salts (3) and (4) at 20°C was σ=6.9×10−2 and 1.5×10−3 S cm−1 with activation energy EA=0.072 and 0.25 eV, respectively, showing the property as semiconductor. The two (1:2) salts (3) and (4) are new, genuine organic magnetic semiconductors.

10-Phenoxyphenothiabismine 5,5-dioxide (2a) and related compounds 2b,c, the first example of an air-stable aryloxybismuthane whose bismuth−oxygen bond is not incorporated into a ring system, were synthesized and fully characterized. Substitution of the OAr group in 2 by phenols in solution revealed two substitution tendencies. The substitution with 2-methoxyphenol proceeded preferentially due to intramolecular coordination of the 2-methoxy oxygen atom with the bismuth atom in 10-(2-methoxyphenoxy)phenothiabismine 5,5-dioxide (2b). Furthermore, the substitution is more favorable with more acidic phenols, which is in accord with the apicophilicity observed at an apical position in hypervalent compounds. 10-(4-Methoxyphenoxy)phenothiabismine 5,5-dioxide (2c) was found to form 10-(4-methoxyphenoxy)phenothiabismine 5,5-dioxide·4-methoxyphenol 1:1 complex (3) through hydrogen bonding between the OH group of 4-methoxyphenol and the aryloxide oxygen atom of 2c. Such complex formation may be the initial step of th...

In the title compounds, [Co(C 2 O 4 )(CH 5 N)) 4 ]ClO 4 (1), and [Co(C 2 O 4 )(C 2 H 7 N) 4 ]ClO 4 .H 2 O, (2), the Co atom has a distorted octahedral coordination composed of four amine ligands and one oxalato ligand. The coordination and oxalato bond distances in (1) and (2) are similar to the corresponding distances in [Co(C 2 O 4 )(NH 3 ) 4 ] + . The Co-N-C angles are in the range 117.1 (4)-123.2 (2)°.

Copper(II) binuclear chromophores [{Cu(H 2 qpda)} 2 ] 4+ ( A ) and [{Cu(H 2 i qpda)} 2 ] 4+ ( B ) were isolated from an acidic aqueous solution of an equimolar H 2 L–CuSO 4 mixture, while H 2 iso-1-qpda gave no copper(II) binuclear complex [H 2 qpda=1,3-bis(quinoline-2-carboxamido)propane, H 2 i qpda=1,3-bis(isoquinoline-3-carboxamido)propane, H 2 iso-1-qpda=1,3-bis(isoquinoline-1-carboxamido)propane]. The crystal structures of A , B and the free ligand H 2 qpda were determined. The coordination structures in both A and B are trans -N 2 O 2 . The copper ions of both complexes are coaxially aligned and hence the heteroaromatic rings are highly stacked. ESR and optical absorption spectroscopies were employed to study their coordination and electronic structures. In the solution, A coexists with aquacopper(II) complex at any [H 2 qpda]/[Cu 2+ ] ratio, and with only a little [Cu(H 2 qpda) 2 ] 2+ mononuclear complex even at [H 2 qpda]/[Cu 2+ ]≥3.0. B coexists with [Cu(H 2 i qpda) 2 ] 2+ but without the aquacopper(II) complex at [H 2 i qpda]/[Cu 2+ ]>1.0. A and [Cu(H 2 O) 5 ] 2+ crystallize in an identical crystal isolated from the equimolar H 2 qpda–CuSO 4 aqueous solution. The trans -N 2 O 2 coordination structure also appears in [Cu(H 2 L) 2 ] 2+ chromophores. The instability of [Cu(H 2 qpda) 2 ] 2+ is ascribed to the trans -N 2 O 2 structure, having serious steric repulsion between the carbonyl oxygen and aromatic hydrogen atoms. Stable [Cu(H 2 i qpda) 2 ] 2+ is free from the steric repulsion. The existence of A possessing two such unstable trans -N 2 O 2 coordination units illustrates the important role of the π–π and hydrophobic interactions in forming the binuclear complex. The formation of B is always greater than that of the homologue [{Cu(H 2 ppda)} 2 ] 4+ [ C ; H 2 ppda=1,3-bis(pyridine - 2-carboxamido)propane]. Both Cu⋯Cu distance and interplanar separation between the stacking aromatic rings in B are significantly shorter than those in C . These results endorse the more effective π–π and hydrophobic interactions in B than C .

Using electron spin resonance (ESR) and visible spectroscopies, coaxially stacked binuclear copper(II) complexes of ω,ω′-bis(pyridine-2-carboxamido)alkanes in acidic aqueous solution (pH 3.8–5.0), H2peda (alkane = ethane), H2ppda (alkane = propane), and H2pbda (alkane = butane), were characterized. trans-1,2-Bis(pyridine-2-carboxamido)cyclohexane or trans-H2pcyhda (alkane = trans-1,2-cyclohexane) did not provide coaxially stacked binuclear complex, because of the lower conformational freedom at the HNCH-CHNH bond. The coaxially stacked structure causes π—π stacking between the pyridyl rings. The conformation of the propanediyl chain is gauche—gauche, while the ethanediyl and butanediyl chains contain an eclipsed conformation. The driving force for the formation of these binuclear complexes in acidic solution is intramolecular π—π stacking interaction between the pyridyl rings in concert with hydrophobic interaction. Although H2ppda gave crystals of a binuclear complex with many lattice water molecules, H2peda and H2pbda ligands provided crystals of copper(II) polymer complexes from the respective acidic solution. The trans-H2pcyhda ligand forms a copper(II) binuclear complex with open-chain structure in acidic solution. Crystal structures of the polymer complexes are also presented.

The crystal structure of the nitridochromium(V) complex [CrN(salophen)]·MeCN [H2salophen=N,N′-bis(salicylidene)-o-phenylenediamine] has been determined. The coordination geometry of this complex, similar to those of all the nitridochromium(V) complexes investigated so far, is square pyramidal with the nitride ion occupying the apex. The ESR parameters of the nitridochromium(V) complexes isolated so far were compared with one another to show an enormous expansion of the 3d electron cloud due to the strong CrN triple bonding. Moderate covalency in the in-plane bonds was also concluded. The nephelauxetic series of three types of the basal ligands is deduced to be salen≈salophen>bpb≈mebpb≈dmebpb>oep≈ttp (in nephlauxetic ratio) for the high-oxidation nitridochromium(V), H2salen=N,N′-bis(salicylidene)ethane-1,2-diamine, H2bpb=1,2-bis(pyridine-2-carboxamido)benzene, H2mebpb=1,2-bis(pyridine-2-carboxamido)-4-methylbenzene, H2dmbpb=1,2-bis(pyridine-2-carboxamido-4,5-dimethylbenzene, H2oep=2,3,7,8,12,13,17,18-octaethylporphyrin and H2ttp=5,10,15,20-tetra-p-tolylporphyrin.

A series of meta- and para-phenylene-bridged Bi(III)n and Bi(V)n compounds (n ≥ 2) have been synthesized. Reaction of Ph2BiX (X = Cl, OSO2CF3) with p-Li2C6H4, p-(BrMg)2C6H4, or p- and m-(Me2S·Cu)2C6H4 generated in situ from dibromobenzenes gave the corresponding para- and meta-phenylene-bridged Bin−bismuthanes, Ph2BiC6H4BiPh2 (2), Ph2BiC6H4Bi(Ph)C6H4BiPh2 (3), and Ph2BiC6H4Bi(Ph)C6H4Bi(Ph)C6H4BiPh2 (4), in 2−30% yields. Bin-bismuthanes 2−4 were oxidatively chlorinated by SO2Cl2 to yield the Bin-bismuth polychlorides 5−7, in which all pentavalent bismuth atoms bore three aryl groups and two chlorine atoms. Compounds 2−7 showed λmax at around 244−249 and 285−290 nm in the UV−vis spectra, suggesting that the phenylene bridges did not perturb significantly the σ- and π-transitions of the aromatic systems in these bismuth oligomers. Ortho-lithiation directed by the sulfonyl group was employed for the one-pot preparation of highly branched Bin-bismuthanes; successive treatment of Ar3Bi 9a with 3 equiv of t-BuLi...

(4-Chlorophenyl){(S)-2-[(R)-1-(dimethylamino)ethyl]ferrocenyl}iodobismuthane (3b), the first example of an optically pure bismuthane, was synthesized with exclusive stereoselectivity using Bi−N intramolecular coordination and the planar chirality of ferrocene. The variable-temperature 1H NMR spectra measured in the range from −50 to +50 °C in CDCl3 revealed that no epimerization takes place at the bismuth center. An X-ray crystallographic study demonstrated that the bismuth atom is diastereoselectively introduced into the substituted cyclopentadienyl ring and that the 4-chlorophenyl group occupies the exo position toward the iron atom. The absolute configuration around the bismuth atom was determined to be R. The longer intramolecular Bi−N distance of 3b [2.71(1) A] compared with those of chloro{2-[(R)-1-(dimethylamino)ethyl]phenyl}phenylbismuthane (1a,b) [2.55(2), 2.57(2) A, respectively] indicates a weaker Bi−N coordination in the ferrocene system. The specific rotation of 3b, [α]D23 −546 (c 1.0, CHCl3)...

The crystal structure of the nitridochromium(V) complex [CrN(salen)] (H2salen = N,N′-bis(salicylidene)ethylenediamine) has been determined. This complex crystallizes in the monoclinic system, space group P21/c, a = 9.575(1), b = 12.322(3), c = 12.999(2) A, β = 103.57(1)°, V = 1490.8(5) A 3 , Z = 4; final R2 = 0.059 (R = 0.054), wR2 = 0.082 (wR = 0.044) for 1935 observed reflections (I⩾1.5σ(l)). The coordination geometry is square pyramidal with an N2O2 donor set (LN202) in the basal plane and the nitride ion at the apex. The UV-Vis spectra of the complex have been re-measured in several solvents and exhibited a d-d band maximum around 540 nm (ϵ ≈200 M−1cm−1). This is the first example of an observed d-d band among the nitridochromium(V) complexes isolated so far. The ESR spectra have been also re-measured in more detail. The ESR parameters have been compared with those of the [CrN(LN4)] complexes and a remarkable nephelauxetic effect of the 3d sub-shell in comparison with the 3s sub-shell is indicated for the nitridochromium(V) complexes.

ESR and optical absorption measurements were performed for six-coordinate Fe(III)TPP-butyl peroxide complexes formed in the reaction system composed of Fe(III)TPPCl, NaOCH 3 and t- or n-butyl hydroperoxide. The presence of four paramagnetic iron complexes was detected in the reaction system. Based on the spectroscopic parameters, the spin state and the axial ligand of these species were deduced as follows: Fe(III)TPP-(HOCH 3 )( − OCH 3 ) ( A ), -( − OCH 3 ) 2 ( B ), ( − OCH 3 )( − OO-butyl) ( C ), -( − OO-butyl) 2 ( D ) coordination reactions of t- and n-butyl hydroperoxide and complexes A and B were monitored on changing the molar ratio of [t- or n-butylperoxide]/ [Fe(III)TPPCl]. The observed spectral changes justified that complexes A and B were successively changed to complex D through complex C . The concentration of these four paramagnetic complexes was estimated by means of the duplicate integration of the observed ESR spectra at 4.2 K. The molar distribution of complexes A, B, C and D was simulated by taking into account the formation constants relating to the generation of the peroxide complexes C and D . By comparison of the formation constants, the possible mechanisms for Fe(III)TPP-peroxide complex formation were discussed.

The cation radical (CR) and charge transfer (CT) salts of 7,10-dithiafluoroanthene with various inorganic and organic acceptors were prepared either by electrocrystallization in the presence of tetraalkylammonium salts or recrystallization of the mixture of donor and acceptors. The structures of these CR and CT salts were determined by X-ray crystallographic analysis and the conductivities of those salts were measured by a four probe method using compaction pellets.

A new type of α-asymmetric bicyclic nitroxides were synthesized by three electron reduction of certain homoallylic nitroenones followed by the reaction with nitro-substituted benzoyl chlorides. Some nitroxides thus obtained turned out to exist as a conglomerate (racemic mixture), an equimolecular mixture of two crystalline enantiomers, and hence induced spontaneous optical resolution upon recrystallization. The relationship between the formation of conglomerates and their molecular and crystral structures is described, together with the preliminary results of their paramagnetic susceptibility mesurements.

The crystal structure of dichloro(5,10,15,20-tetraphenylporphinato)phosphorus(V) chloride dichloromethane solvate has been determined by X-ray diffraction at ambient temperature. A saddle shape of the meso-tetraphenylporphinate disc is attributed to marked S4 deviation from planarity. The mode of the torsion of four phenyl rings around the CC bonds connecting these rings to the respective meso carbon atoms are also of S4 character. The phosphorus atom lies just in the mean plane of the porphinate nitrogen atoms. The PN bond distances range from 1.804(3) to 1.821(3) A, which are shorter than those observed in [P(OH)2(tpp)]+ (1.870–1.916 A), while the axial PCl bond distances [2.149(1) and 2.153(1) A] are significantly longer than the distance expected for the normal covalent PCl bond (2.10 A). This phosphorus porphyrin reveals characteristic features peculiar to the structure of metalloporphyrins with the smallest-sized central cations.

An electron paramagnetic resonance (EPR) study has been carried out on a single crystal of trans-[VOCl2(H2O)2](18- crown-6)·2H2O or adduct of trans-diaquadichlorooxovanadium(IV) with 1,4,7,10,13,16-hexaoxacyclooctadecane (abbr. 18C6) at ambient temperature. This crystal belongs to a centric triclinic space group, and the chromophore and crown ether alternate to form a magnetically diluted vanadyl system. The EPR study has revealed the rhombic spin Hamiltonian parameters gz = 1.952(1), gx = 1.985(2), gy = 1.990(3), ∣Az∣ = 18.8(3), ∣Ax∣ = 7.6(3) and ∣Ay∣ > 5.5 mT, where the z, x and y principal axes are along the VO and nearly along the VOH2 and VCl bonds, respectively. Errors of these parameters are large, especially in Ay, owing to many broad hyperfine linewidths resulting in overlapping. A negative sign is suggested for all the principal A values. Three d-d* transitions, dxy→dyz (12.9 kcm−1), dxy→dyz (15.2) and dxy→dx2−y2 (17.0), and a charge-transfer transition, a1(related to dx2−y2)→a2(dxy) (27–28 kcm−1) from the acetone solution, were assigned. The trans-[VOCl2(H2O)2] species is not dissociated in acetone and 2-propanol solution, but the chloro ligands are substituted with aqua ligands when there is a lot of water in the solution.

The title complexes trans (O)-(Co(aeida)Cl(H 2 O)] ( A ) and mer (N)-[CoCl (i-dtma)(H 2 O)] ClO 4 ( B ) crystallize as a conglomerate (H 2 aeida = N-(2-aminoethyl)-N-(carboxymethyl)glycine, Hi-dtma = N,N-bis(2-aminoethyl)glycine). The X-ray crystallographic analysis shows that single crystals of A and B are chiral. Although the conglomerate formation of either A and B was not observed in the crystal morphology under a microscope, it was confirmed by the Weissenberg photography method. In A , the chirality originates from the δ or λ conformation of the ethylenediamine chelate ring. In B it originates from the fact that chiralities due to the δ and λ conformation of the two ethylenediamine chelate rings in the complex do not cancel out, owing to the asymmetry derived from the rotational configuration of the aqua ligand. These chiral molecular configurations are closely related with intermolecular hydrogen bonds in the crystal.

The crystal structures of molecular adducts of vanadyl complex of trans-[VOCl2(H2O)2] with 15-crown-5 (15C5), benzo-15-crown-5 (B15C5) have been studied by X-ray diffraction at ambient temperature. The adduct of the same complex with 18-crown-6 (18C6) recrystallized from a solvent different from that previously reported, has been also re-refined and the unresolved chloro position has been resolved into two disordered positions. The ClVCl bond angles in the 15C5 and B15C5 adduct are 143° and 145°, respectively, which are smaller than the OVO bond angles of 153° and 154°. There appear eclipsed type H2O-VCl2 conformations in all the adducts. These observations can be ascribed to the steric repulsion between the chloro ligands and aqua hydrogen atoms as well as to the coulombic repulsion between the chloro and oxido ligand. The crystals are composed of adduct polymers with 1 : 1 stoichiometry in which the chromophore and crown ether alternate along the polymer axis. The polymers are formed by hydrogen bonding between the aqua ligand and the oxygen atoms on the crown ring. The crown ethers adopt invariably all-gauche CC conformation. The OC bonds are of trans conformation except for a gauche OC bond in 15C5. ESR parameters of trans-[VOCl2(H2O)2] observed for the 15C5 adduct powder are also presented.

A series of five copper(II) complexes with four geometrically isomeric ligands of 1,4,7,10-tetrabenzyl-2,5,8,11-tetraethyl-1,4,7,10-tetraazacyclododecane and with (2R,5R,8R,11R)-2,5,8,11-tetraethyl-1,4,7,10-tetraazacyclododecane has been investigated by means of ESR, CD and MCD in solution. X-ray studies reported separately had shown that the [CuN4Cl] chromophores were distorted to varying extents from square pyramidal to trigonal bipyramidal geometry. The stability and rigidity of the molecular structure have enabled us to carry out a complementary study of the crystalline state and solution chemistry. The ground state Kramers doublets varied from 3dx2−y2 to 3dz2 type with increasing distortion around the copper ion. The orbital sequence of the 3d1 positive hole, dx2−y2

The crystal structures of [Co(hfac)(en) 2 ](ClO 4 ) 2 ( I ) and β-[Co(hfac) (trien)](ClO 4 ) 2 ( II ) have been determined by X-ray diffraction at ambient temperature, where Hfac = hexafluoro-2,4-pentanedione, en = ethylenediamine and trien = 1,8-diamino-3,6-diazaoctane. The relative configuration of the cation in II is rel -Δ- RR . Their molecular structures are compared with those previously reported for [Co(hfacOH)(en) 2 ] + , [Co(hfacOH 3 )(en) 2 ] + and β-[Co(hfacOCH 3 )(trien)] + , in which an OH − or OCH 3 − anion is covalently combined with one of the carbonyl carbon atoms on the hfac ligand. The quasiaromaticity of the coordinating hfac ligand in I and II was structurally characterized.

Oxidation of triphenylbismuthine 1 with ozone in toluene at –78°C gave, unexpectedly, a high yield of triphenylbismuth diformate 3, which was also obtainable as a minor product by a similar oxidation in ethyl acetate and acetone. An X-ray crystallographic study revealed that compound 3 has C2 symmetry, the geometry around the bismuth atom being best described as a distorted trigonal bipyramid as a result of strong intramolecular interaction between the bismuth and carbonyl oxygen atoms. Treatment of compound 3 with aqueous sodium acetate or halides readily converted it into the corresponding triphenylbismuth diacetate 5 or dihalides 7–9.

In the presence of the optimum amount of water, the ESR spectra of copper(II) complexes of 5-oxygen donors observed in BF3-etherate solution revealed a typical g-anisotropy ascribed to the 3dz2 type copper(II) complex. Based on the detection of superhyperfine splittings due to 17O isotope, the axial ligation of water molecule was confirmed, and the coordination geometry of the complex was assumed.

In the presence of the optimum amount of water, the copper(II) ion and 15-crown-5 (15C5) derivatives gave the dihydrated complex in boron trifluoride–diethyl ether (BF3–ether). Based on optical and ESR spectrometric titrations, we found that the crown ether captures the copper(II) ion in the equivalent metal/ligand molar ratio. The d–d band absorptions of the complexes were detected in the near-infrared region. The complexes revealed the characteristic ESR g-anisotropies (gz

Matrix isolation ESR study showed that the ligated HCCO− ion was decomposed into H+ and ·COO− radical anion through CTTM process at λ = 254 nm, by contrast, ·CH3 radical and CO2 were produced from CH3COO− ligand. In order to explain the photo- and related reactions in the liquid solution, a proposal is made for a cyclic scheme conjugated with the photo-decomposition of the complex. The cycle consists of three steps; photo-reduction of H+ by Eu2+, radical alternation from ·H to ·COO−, and oxidation of ·COO− by Eu3+.