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Bronislaw Marciniak - One of the best experts on this subject based on the ideXlab platform.
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Electron paramagnetic resonance (EPR) study of γ-radiation-induced radicals in 1,3,5-Trithiane and its derivatives
Research on Chemical Intermediates, 2009Co-Authors: Grazyna Strzelczak, Bronislaw Marciniak, Edyta Janeba-bartoszewicz, Ian Carmichael, Krzysztof BobrowskiAbstract:Radicals formed in γ-irradiated 1,3,5-Trithiane (TT) and its three derivatives, α- and β-2,4,6-trimethyl-1,3,5-Trithiane (α-TMT and β-TMT), and 2,4,6-trimethyl-2,4,6-triphenyl-1,3,5-Trithiane (TMTPT), were studied by the electron paramagnetic resonance (EPR) method in the solid state. The sulfur radical cations (>S^+•) were identified in all compounds at 77 K. In TT and its two derivatives, α-TMT and β-TMT, the >S^+• decay via deprotonation-forming C-centered radicals. Further increase of temperature up to 293 K results in the appearance of thiyl-type radicals (RS^•). In TMTPT, the >S^+• are stable up to 250 K. They formed the intermolecularly three-electron-bonded dimeric radical cations (S∴S)^+ while RS^• radicals were not observed. Some of the radical assignments and their EPR parameters ( g and a hyperfine splittings) obtained support from the DFT calculations.
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Photoinduced ultrafast ring-opening reaction in Trithianes in solution
Chemical Physics Letters, 2008Co-Authors: Gotard Burdzinski, Bronislaw MarciniakAbstract:Abstract The ring-opening reaction of Trithianes possessing aromatic substituents has been studied using femtosecond broadband UV–Vis transient absorption spectroscopy. Photocleavage of the C S bond occurs during the short-lived (1.5 ps) singlet excited state of Trithiane. The products are formed with excess of vibrational energy and cooling of the hot molecules occurs with a 12.1 ps time constant in acetonitrile.
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Evidence for Heterolytic Cleavage of C-S Bonds in the Photolysis of 1,3,5-Trithianes
Polish Journal of Chemistry, 2008Co-Authors: Gordon L. Hug, Edyta Janeba-bartoszewicz, Piotr Filipiak, Tomasz Pedzinski, Halina Kozubek, Bronislaw MarciniakAbstract:The homolytic/heterolytic nature of photolytic C-S bond cleavage was studied in 1,3,5-Trithianes. The mechanism of photolysis was refined from previous studies. First, evidence was presented for the existence of a precursor of the biradical-like transient (I) which itself was identified in previous studies. Second, the nature of I was further clarified through methanol-scavenging experiments where the results could be interpreted as lending credibility to the notion that / has significant bipolar character. Kinetic and spectral analyses of transient absorptions, following laser excitation of the Trithianes, showed that I was reacting with methanol. Complementary steady-state photolytic quantum yields supported this finding, and additional, but unidentified, stable products from irradiations in methanol were seen in the HPLC. The formation of these products was interpreted as likely arising from a nucleophilic attack of methanol at the carbocationic end of the bipolar structure of I.
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Photochemistry of 1,3,5-Trithianes in solution: Steady-state and laser flash photolysis studies
Journal of Photochemistry and Photobiology A: Chemistry, 2006Co-Authors: Edyta Janeba-bartoszewicz, Ewa Andrzejewska, Gordon L. Hug, Bronislaw MarciniakAbstract:Abstract In this work, we characterized the direct photochemistry of a set of five structurally-related 1,3,5-Trithianes. The compounds were 1,3,5-Trithiane, the α- and β-isomers of the 2,4,6-trimethyl derivatives, and the α- and β-isomers of the 2,4,6-triphenyl derivatives. Under steady-state, 254-nm irradiation of acetonitrile solutions of all five Trithianes, dithioesters of the form RC( = S)SCH(R)SCH 2 R were identified and shown to be primary photoproducts (R = H, CH 3 , or C 6 H 5 ). Shorter dithioesters, RC( = S)SCH 2 R, were also identified and shown to be secondary products. The presence of the dithioesters could be monitored by their strong absorption bands in the region of 310 nm. This same band was evident following the laser flash photolysis of the five Trithianes. The laser-induced transient spectra showed another absorbing species ( I ) in all five Trithianes. This species was not stable and showed a complementary decay that matched the growth of the stable photoproducts at 310 nm. This suggested that the intermediates ( I ) are the precursors of the corresponding dithioesters, RC( = S)SCH(R)SCH 2 R. These correlated processes were related to monophotonic events. However, in the laser flash photolysis experiments in the triphenyl derivatives, there was an additional pathway for the formation of the dithioesters, and this was biphotonic. When the biphotonic formation of products was compensated for, RC( = S)SCH(R)SCH 2 R formation quantum yields from steady-state and laser flash photolysis matched within experimental error. The absorption band of ( I ) varied systematically with substituents, 320 nm in 1,3,5-Trithiane, 340 nm in the 2,4,6-trimethyl derivatives, and 420 nm in the 2,4,6-triphenyl derivatives. The nature of these intermediates ( I ) were discussed as resulting from C S bond cleavage, probably heterolytic.
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Trithianes as coinitiators in benzophenone-induced photopolymerizations
Macromolecules, 1999Co-Authors: Ewa Andrzejewska, Gordon L. Hug, Maciej Andrzejewski, Bronislaw MarciniakAbstract:A series of 1,3,5-Trithiane derivatives, including α- and β-isomers of the methyl and phenyl derivatives, was investigated for use as coinitiators in benzophenone-induced photopolymerizations. To s...
U M Dzhemilev - One of the best experts on this subject based on the ideXlab platform.
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Effective synthesis of N-substituted 1,3,5-dithiazinanes by reactions of N-methyl-1,3,5-dithiazinane and 1,3,5-Trithiane with aromatic amines
Russian Journal of Organic Chemistry, 2011Co-Authors: E B Rakhimova, A G Ibragimov, I. V. Vasil’eva, L. M. Khalilov, U M DzhemilevAbstract:A novel procedure has been developed for selective synthesis of N -aryl-1,3,5-dithiazinanes, 1,2,6,7-tetrahydro-3,5,1,7-benzodithiadiazonine, and 6,7-dihydro-1,3,5,7-benzotrithiazonine by reactions of aniline derivatives with N -methyl-1,3,5-dithiazinane or 1,3,5-Trithiane in the presence of transition and rare earth metal salts and complexes.
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a new method for the synthesis of n substituted 1 3 5 dithiazinanes via the catalytic recyclization of 1 3 5 Trithiane with aryl benzyl hydrazines and aryl amines
Tetrahedron Letters, 2011Co-Authors: Nataliya N Murzakova, E B Rakhimova, Inna V Vasilyeva, Kirill I Prokofyev, A G Ibragimov, U M DzhemilevAbstract:An efficient method for the synthesis of N-substituted 1,3,5-dithiazinanes based on the amination reaction of 1,3,5-Trithiane with aryl(benzyl) hydrazines and N-aryl amines in the presence of Ti and Fe catalysts has been developed.
Chansa Cha - One of the best experts on this subject based on the ideXlab platform.
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Computational study of the conformational interconversion of 5,5‐dimethyl‐1,2,3‐trithiacyclohexane (5,5‐dimethyl‐1,2,3‐Trithiane)
International Journal of Quantum Chemistry, 2004Co-Authors: Fillmore Freeman, Chansa ChaAbstract:Ab initio molecular orbital theory and density functional theory (DFT) with the 6-31G(d), 6-31G(d,p), 6-31+G(d,p), and 6-311+G(d,p) basis sets have been used to study the mechanism of conformational interconversion of 5,5-dimethyl-1,2,3-trithiacyclohexane (5,5-dimethyl-1,2,3-Trithiane). The relative energies, enthalpies, entropies, free energies, and structural parameters of the chair, 1,4-twist, and 2,5-twist conformers, the 1,4-boat transition state, and the 2,5-boat transition state were calculated. B3LYP/6-31+G(d,p) calculated the chair conformer of 5,5-dimethyl-1,2,3-Trithiane to be 8.38 and 8.72 kcal/mol, respectively, lower in energy than the 1,4-twist and 2,5-twist conformers. The energy differences (ΔE) between the chair conformer of 5,5-dimethyl-1,2,3-Trithiane and the 1,4-boat transition state and the 2,5-boat transition state were 8.95 and 11.46 kcal/mol, respectively. Intrinsic reaction coordinate [IRC, minimum energy path (MEP)] calculations were used to connect the transition state between the chair conformer and 2,5-twist conformer. B3LYP/6-31+G(d,p) calculated energy differences (ΔE) between the chair conformer and the transition state [TS-1]‡ connecting the chair and 2,5-twist conformers to be 14.23 kcal/mol. In the chair, 1,4-twist, and 2,5-twist conformers, the C4Heq bond is slightly longer than the C4Hax bond. The C5C8eq bond is longer than the C5C7ax bond in the chair and 1,4-twist conformers. In the 1,4-twist conformer, the S1S2 bond is longer than the S3S3 bond and the S1C6 bond is longer than the S3C4 bond. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
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computational study of the conformational interconversion of 5 5 dimethyl 1 2 3 trithiacyclohexane 5 5 dimethyl 1 2 3 Trithiane
International Journal of Quantum Chemistry, 2004Co-Authors: Fillmore Freeman, Chansa ChaAbstract:Ab initio molecular orbital theory and density functional theory (DFT) with the 6-31G(d), 6-31G(d,p), 6-31+G(d,p), and 6-311+G(d,p) basis sets have been used to study the mechanism of conformational interconversion of 5,5-dimethyl-1,2,3-trithiacyclohexane (5,5-dimethyl-1,2,3-Trithiane). The relative energies, enthalpies, entropies, free energies, and structural parameters of the chair, 1,4-twist, and 2,5-twist conformers, the 1,4-boat transition state, and the 2,5-boat transition state were calculated. B3LYP/6-31+G(d,p) calculated the chair conformer of 5,5-dimethyl-1,2,3-Trithiane to be 8.38 and 8.72 kcal/mol, respectively, lower in energy than the 1,4-twist and 2,5-twist conformers. The energy differences (ΔE) between the chair conformer of 5,5-dimethyl-1,2,3-Trithiane and the 1,4-boat transition state and the 2,5-boat transition state were 8.95 and 11.46 kcal/mol, respectively. Intrinsic reaction coordinate [IRC, minimum energy path (MEP)] calculations were used to connect the transition state between the chair conformer and 2,5-twist conformer. B3LYP/6-31+G(d,p) calculated energy differences (ΔE) between the chair conformer and the transition state [TS-1]‡ connecting the chair and 2,5-twist conformers to be 14.23 kcal/mol. In the chair, 1,4-twist, and 2,5-twist conformers, the C4Heq bond is slightly longer than the C4Hax bond. The C5C8eq bond is longer than the C5C7ax bond in the chair and 1,4-twist conformers. In the 1,4-twist conformer, the S1S2 bond is longer than the S3S3 bond and the S1C6 bond is longer than the S3C4 bond. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
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Computational study of the chair–chair interconversion and stereoelectronic interactions in 1,2,3‐trithiacyclo‐hexane (1,2,3‐Trithiane)
Journal of Physical Organic Chemistry, 2004Co-Authors: Fillmore Freeman, Chansa ChaAbstract:Ab initio theory, density functional theory (DFT) and Moller–Plesset perturbation theory (MP2) with the 6–31G(d), 6–31++G(d), 6–31G(d,p), 6–31+G(d,p), 6–31++G(d,p), 6–311G(d,p) and 6–311+G(d,p) basis sets were used to study stereoelectronic hyperconjugative interactions and the mechanism of the chair–chair conformational interconversion in 1,2,3-trithiacyclohexane (1,2,3-Trithiane). The relative energies, enthalpies, entropies, free energies and structural parameters of the chair, 1,4-twist and 2,5-twist conformers, a distorted 1,4-boat transition state and a 2,5-boat transition state were calculated. The HF calculated energy difference (ΔE) between the chair conformer of 1,2,3-Trithiane and the distorted 1,4-boat transition state was 10.59 kcal mol−1 (1 kcal=4.184 kJ). The 1,4-twist conformer and the 2,5-boat transition state are close in energy, as are the 2,5-twist conformer and the distorted 1,4-boat transition state. B3LYP/6–311+G(d,p) calculated the chair conformer of 1,2,3-Trithiane to be 5.83, 10.09, and 5.96 kcal mol−1, respectively, lower in energy than the 1,4-twist conformer, 2,5-twist conformer and 2,5-boat transition state. Intrinsic reaction coordinate (IRC) calculations were used to connect the transition state between the chair conformer and the 1,4-twist conformer. B3LYP/6–31+G(d,p) and B3LYP/6–311+G(d,p) calculated this transition state to be 14.25 kcal mol−1 higher in energy than the chair conformer. In the chair conformer, the respective C4—H and C6—H bond lengths are equal, but the C5—Heq bond is longer than the C5—Hax bond. In the 1,4-twist conformer, the C4—Hiso bond lengths are equal, the C5—Hψeq bond is longer than the C5—Hψax bond and the C6—H bond lengths are equal. In the 2,5-twist conformer, equal C—H bond lengths are found at C4 and at C5, but the C6—Hψeq bond is longer than the C6—Hψax bond. Copyright © 2003 John Wiley & Sons, Ltd. Additional material for this paper is available in Wiley Intersciene
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computational study of the chair chair interconversion and stereoelectronic interactions in 1 2 3 trithiacyclo hexane 1 2 3 Trithiane
Journal of Physical Organic Chemistry, 2004Co-Authors: Fillmore Freeman, Chansa ChaAbstract:Ab initio theory, density functional theory (DFT) and Moller–Plesset perturbation theory (MP2) with the 6–31G(d), 6–31++G(d), 6–31G(d,p), 6–31+G(d,p), 6–31++G(d,p), 6–311G(d,p) and 6–311+G(d,p) basis sets were used to study stereoelectronic hyperconjugative interactions and the mechanism of the chair–chair conformational interconversion in 1,2,3-trithiacyclohexane (1,2,3-Trithiane). The relative energies, enthalpies, entropies, free energies and structural parameters of the chair, 1,4-twist and 2,5-twist conformers, a distorted 1,4-boat transition state and a 2,5-boat transition state were calculated. The HF calculated energy difference (ΔE) between the chair conformer of 1,2,3-Trithiane and the distorted 1,4-boat transition state was 10.59 kcal mol−1 (1 kcal=4.184 kJ). The 1,4-twist conformer and the 2,5-boat transition state are close in energy, as are the 2,5-twist conformer and the distorted 1,4-boat transition state. B3LYP/6–311+G(d,p) calculated the chair conformer of 1,2,3-Trithiane to be 5.83, 10.09, and 5.96 kcal mol−1, respectively, lower in energy than the 1,4-twist conformer, 2,5-twist conformer and 2,5-boat transition state. Intrinsic reaction coordinate (IRC) calculations were used to connect the transition state between the chair conformer and the 1,4-twist conformer. B3LYP/6–31+G(d,p) and B3LYP/6–311+G(d,p) calculated this transition state to be 14.25 kcal mol−1 higher in energy than the chair conformer. In the chair conformer, the respective C4—H and C6—H bond lengths are equal, but the C5—Heq bond is longer than the C5—Hax bond. In the 1,4-twist conformer, the C4—Hiso bond lengths are equal, the C5—Hψeq bond is longer than the C5—Hψax bond and the C6—H bond lengths are equal. In the 2,5-twist conformer, equal C—H bond lengths are found at C4 and at C5, but the C6—Hψeq bond is longer than the C6—Hψax bond. Copyright © 2003 John Wiley & Sons, Ltd. Additional material for this paper is available in Wiley Intersciene
Georg Süss-fink - One of the best experts on this subject based on the ideXlab platform.
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Face versus vertex co-ordination of tridentate crown thioethers to trinuclear cobalt clusters
J. Chem. Soc. Dalton Trans., 1996Co-Authors: Corinne Renouard, Georg Süss-fink, Gerd Rheinwald, Helen Stoeckli-evans, Dario Braga, Fabrizia GrepioniAbstract:The co-ordination of the six-membered crown thioethers 1,3,5-Trithiane, 2-methyl-, 2,4-dimethyl-, 2,4,6-trimethyl-, 2-benzyl- and 2,4,6-tribenzyl-1,3,5-Trithiane and the nine-membered crown thioether 1,4,7-trithiacyclononane to the cobalt skeleton of various Co3C clusters was studied. With Trithiane and its derivatives complexes of the type [Co3(CO)6(µ3-SCHR1SCHR2SCHR3)](R = Cl, Me or Ph; R1– R3= H, Me or CH2Ph) were obtained, whereas the nine-membered crown thioether gave compounds of the type [Co3(CO)5(µ-CO)(µ3-CR){(SCH2CH2)3}]. The molecular and crystal structures of several representatives have been investigated by single-crystal X-ray diffraction. It has been shown that the Trithiane ligand invariably occupies the axial co-ordination sites on the three cobalt atoms, while the trithiacyclononane chelates on one cobalt atom. The intermolecular networks of hydrogen-bonding interactions of the C–H ⋯ O type between the thioether hydrogens and the CO ligands have been investigated and compared with those present in other crystalline clusters carrying thioether ligands.
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Intramolecular site exchange of carbonyl ligands in the cluster compounds nonacarbonyl {μ3-[η3-(1,3,5-Trithiane)]}triruthenium ([Ru3(CO)9{μ3-(η3-C3H6S3)}]) and (tert-butyl isocyanide)octacarbonyl-{μ3-[η3-(1,3,5-Trithiane)]}triruthenium ([Ru3(t-BuNC)(
Helvetica Chimica Acta, 1993Co-Authors: Gábor Laurenczy, A. Merbach, Bertrand Moullet, Raymond Roulet, Lisa Hoferkamp, Georg Süss-finkAbstract:Variable-temperature and -pressure 13C-NMR studies of the 1,3,5-Trithiane-capped triruthenium clusters [Ru3(CO)9{μ3-(η3-1,3,5-Trithiane)}] (1) and [Ru3(t-BuNC)(CO)8{μ3-(η3-1,3,5-Trithiane)}] (2) revealed that CO site exchanges occur via an intramolecular merry-go-round process, involving a transition state mostly dissociative in character.
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Fixation of 1,3,5‐Trithiane to a Trinuclear Ruthenium Framework: Synthesis, structure, and fluxionality of [Ru3(CO)6(μ2‐CO)3{μ3‐(η3‐C3S3H6)}]
Helvetica Chimica Acta, 1992Co-Authors: Lisa Hoferkamp, Gerd Rheinwald, Helen Stoeckli-evans, Georg Süss-finkAbstract:The reaction of dodecacarbonyltriruthenium with 1,3,5-trithiacyclohexane (1,3,5-Trithiane) in refluxing THF yields [Ru3(CO)6(μ2-CO)3{μ3-(η3-C3S3H6)}] (1) in which the three S-atoms of the cyclic ligand coordinate to the three Ru-atoms of the metal core. X-Ray diffraction reveals a nearly perfect C3v symmetry for the molecule. The variable-temperature 13C-NMR spectra show the carbonyl ligands to be fluxional in solution.
Lisa Hoferkamp - One of the best experts on this subject based on the ideXlab platform.
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Intramolecular site exchange of carbonyl ligands in the cluster compounds nonacarbonyl {μ3-[η3-(1,3,5-Trithiane)]}triruthenium ([Ru3(CO)9{μ3-(η3-C3H6S3)}]) and (tert-butyl isocyanide)octacarbonyl-{μ3-[η3-(1,3,5-Trithiane)]}triruthenium ([Ru3(t-BuNC)(
Helvetica Chimica Acta, 1993Co-Authors: Gábor Laurenczy, A. Merbach, Bertrand Moullet, Raymond Roulet, Lisa Hoferkamp, Georg Süss-finkAbstract:Variable-temperature and -pressure 13C-NMR studies of the 1,3,5-Trithiane-capped triruthenium clusters [Ru3(CO)9{μ3-(η3-1,3,5-Trithiane)}] (1) and [Ru3(t-BuNC)(CO)8{μ3-(η3-1,3,5-Trithiane)}] (2) revealed that CO site exchanges occur via an intramolecular merry-go-round process, involving a transition state mostly dissociative in character.
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intramolecular site exchange of carbonyl ligands in the cluster compounds nonacarbonyl μ3 η3 1 3 5 Trithiane triruthenium ru3 co 9 μ3 η3 c3h6s3 and tert butyl isocyanide octacarbonyl μ3 η3 1 3 5 Trithiane triruthenium ru3 t bunc co 8 μ3 η3 c3h6s3
Helvetica Chimica Acta, 1993Co-Authors: Gábor Laurenczy, A. Merbach, Bertrand Moullet, Raymond Roulet, Lisa Hoferkamp, Georg SussfinkAbstract:Variable-temperature and -pressure 13C-NMR studies of the 1,3,5-Trithiane-capped triruthenium clusters [Ru3(CO)9{μ3-(η3-1,3,5-Trithiane)}] (1) and [Ru3(t-BuNC)(CO)8{μ3-(η3-1,3,5-Trithiane)}] (2) revealed that CO site exchanges occur via an intramolecular merry-go-round process, involving a transition state mostly dissociative in character.
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Fixation of 1,3,5‐Trithiane to a Trinuclear Ruthenium Framework: Synthesis, structure, and fluxionality of [Ru3(CO)6(μ2‐CO)3{μ3‐(η3‐C3S3H6)}]
Helvetica Chimica Acta, 1992Co-Authors: Lisa Hoferkamp, Gerd Rheinwald, Helen Stoeckli-evans, Georg Süss-finkAbstract:The reaction of dodecacarbonyltriruthenium with 1,3,5-trithiacyclohexane (1,3,5-Trithiane) in refluxing THF yields [Ru3(CO)6(μ2-CO)3{μ3-(η3-C3S3H6)}] (1) in which the three S-atoms of the cyclic ligand coordinate to the three Ru-atoms of the metal core. X-Ray diffraction reveals a nearly perfect C3v symmetry for the molecule. The variable-temperature 13C-NMR spectra show the carbonyl ligands to be fluxional in solution.
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fixation of 1 3 5 Trithiane to a trinuclear ruthenium framework synthesis structure and fluxionality of ru3 co 6 μ2 co 3 μ3 η3 c3s3h6
Helvetica Chimica Acta, 1992Co-Authors: Lisa Hoferkamp, Gerd Rheinwald, Helen Stoecklievans, Georg SussfinkAbstract:The reaction of dodecacarbonyltriruthenium with 1,3,5-trithiacyclohexane (1,3,5-Trithiane) in refluxing THF yields [Ru3(CO)6(μ2-CO)3{μ3-(η3-C3S3H6)}] (1) in which the three S-atoms of the cyclic ligand coordinate to the three Ru-atoms of the metal core. X-Ray diffraction reveals a nearly perfect C3v symmetry for the molecule. The variable-temperature 13C-NMR spectra show the carbonyl ligands to be fluxional in solution.
