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Grzegorz Mloston

Publications and source records attributed to Grzegorz Mloston.

10 recordsLinked to original sources
PubMed2006

Study on platinum(II) induced formation of dithiiranes.

The reaction of a series of stable alpha-chlorinated oligosulfanes 2 and 3 with [Pt(eta(2)-C(2)H(4))(Ph(3)P)2] 1 have been investigated. Starting with the alpha-chlorodisulfanes 2 a,b, the platinum dichloride complex 5 and the side-on bonded thioketone platinum complexes 6 a,b were formed. Complex 1 was treated with corresponding trisulfanes 3 a,b to give 5, 6 a,b and the dithiolatocomplexes 7 a,b. We assume that the {Pt(0)(Ph(3)P)2}-complex fragment inserted along the S--S bond to form the unstable intermediate G, which decomposed to form the products described above. We could prove that the sterically crowded 1,2,4-trithiolane 8 was not involved in the reaction pathway by treatment of 1 with 8 under the same conditions; after 24 h, 8 was found to be unreacted. X-ray structure analyses were performed on complexes 6 a, 7 a and 7 b.

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PubMed2004

Bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)pentasulfane: an occupancy modulated structure.

The title compound crystallizes in the space group P2(1)/n and may be described by a partial ordering of a 1:1 disordered P2(1)/a parent structure with the c axis halved. The pentasulfane chain completes a full turn of a helix, which gives molecules containing left- or right-handed helices similar spatial requirements and allows them to be interchanged. The structure can be redescribed as containing 0.732 (1) of an ordered P2(1)/n structure and 0.268 (1) of a 1:1 disordered P2(1)/a structure, implying that 0.134 (1) of the molecule sites contain molecules of the opposite hand to that predicted by an ordered P2(1)/n structure. It is found that the average molecular position in the asymmetric unit is not the same for each component and that these structural differences must be recognized to obtain a satisfactory refinement.

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PubMed2003

1,3-dithiolanes from cycloadditions of alicyclic and aliphatic thiocarbonyl ylides with thiones: regioselectivity.

The regiochemistry of 1,3-dithiolanes obtained from thiocarbonyl ylides 9 and thiones 10 shows a striking dependence on substituents. Previously and newly performed experiments indicate that sterically hindered cycloalkanethione S-methylides and dialkylthioketone S-methylides react with alicyclic and aliphatic thiones to give the 2,2,4,4-tetrasubstituted 1,3-dithiolanes 11 exclusively. Aryl groups in one or both reactants lead to a preference for, or even complete formation of, 4,4,5,5-tetrasubstituted 1,3-dithiolanes 12. Several mechanisms appear to be involved, but the paucity of experimental criteria is troubling. Quantum-chemical calculations (see preceding paper) on the cycloaddition between thioacetone S-methylide and thioacetone furnish lower activation energies for the concerted process than for the two-step pathways via C,S- or C,C-biradicals; the favoring of the 2,4-substituted 1,3-dithiolanes over the 4,5-substituted type would be expected to increase with growing bulk of substituents. Aryl groups stabilize intermediate biradicals. Experimental criteria for the differentiation of regioisomeric dithiolanes are discussed. Thiocarbonyl ylides 9 are prepared by 1,3-cycloadditions between diazomethane and thioketones and subsequent N(2) elimination from the usually isolable 2,5-dihydro-1,3,4-thiadiazoles 17; different ratios of the two rate constants lead to divergent product formation scenarios.

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PubMed2002

Highly sulfurated heterocycles via dithiiranes and trithietanes as key intermediates.

2,2,4,4-Tetramethyl-3-thioxocyclobutanone (8b) easily reacts with gaseous chlorine to yield the stable alpha-chloro sulfenyl chloride 10. The same product was obtained when 8b was treated either with phosphorus pentachloride (PCl(5)) or sulfuryl chloride (SO(2)Cl(2)) in CCl(4) solution. Sulfur dichloride (SCl(2)) reacts with 8b to give the alpha-chloro thiosulfenyl chloride 12 along with an almost equimolar amount of the trisulfide 13b. The less reactive disulfur dichloride (S(2)Cl(2)) was shown to react slowly with 8b and the symmetrical tetrasulfide 15 was found as the exclusive product. The pure thiosulfenyl chloride 12 added to adamantanethione (8c) yielded the unsymmetrical trisulfide 13c. When 12 was treated with thioacetic acid, the acetylated trisulfide 17 was formed in high yield. "Unzipping" reactions with the acetylated disulfide 16 and trisulfide 17 with morpholine in THF at -40 degrees C led to the formation of mixtures of two sulfur-rich heterocycles identified as the pentathiepane 6b and the hexathiepane 7b. A mixture of analogous products was obtained when alpha-chloro sulfenyl chloride 10 was treated with sodium sulfide in anhydrous THF at -40 degrees C. The formation of 6b and 7b is believed to occur via the intermediate dithiirane 1b and/or the isomeric thiosulfine 2b. In the case of 17 the reaction starts probably with the formation of a nonisolable tetrathiane 18b as presented in Scheme 5.

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PubMed2002

Four bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)oligosulfanes.

The four oligosulfanes, bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)disulfane, C(16)H(24)Cl(2)O(2)S(2), (III), 1,3-bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)trisulfane, C(16)H(24)Cl(2)O(2)S(3), (V), 1,4-bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)tetrasulfane, C(16)H(24)Cl(2)O(2)S(4), (VII), and 1,6-bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)hexasulfane, C(16)H(24)Cl(2)O(2)S(6), (VIII), all have similar geometric parameters, with the C-C bond lengths involving the chloro-substituted cyclobutanyl C atom being elongated to about 1.59 A. There are two molecules in the asymmetric units of the tri- and tetrasulfanes, and the molecules in the latter compound have local C(2) symmetry. The molecule of the hexasulfane has crystallographic C(2) symmetry. Most of the cyclobutanyl rings are not perfectly planar and have slight but varying degrees of distortion towards a flattened tetrahedron. The polysulfane chain in each structure has a helical conformation, with each additional S atom in the chain adding approximately one quarter of a turn to the helix.

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PubMed2002

Relative reactivities of carbonyl and thiocarbonyl groups toward dimethoxycarbene: two new dimethoxythiiranes.

Reaction of dimethoxycarbene (DMC), generated by thermolysis of a 2,5-dihydro-1,3,4-oxadiazole, with 2,2,4,4-tetramethyl-3-thioxocyclobutanone afforded primarily 2,2-dimethoxy-3,3,5,5-tetramethyl-4-thioxocyclopentanone from ring expansion by overall insertion into the C-CO bond. 4,4-Dimethoxy-2,2,5,5-tetramethyl-3-thioxocyclopentanone, from overall insertion into a C-CS bond, was a minor product. Thus the carbene had reacted preferentially at the carbonyl group, rather than the thiocarbonyl group of the four-membered ring. However, the minor product reacted with DMC at the thiocarbonyl group to afford a dimethoxythiirane. A product from a corresponding reaction at the carbonyl group could not be found. A rationale for the apparent reversal of relative reactivities of the carbonyl and thiocarbonyl groups is offered, with supporting evidence.

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PubMed2002

The dimer, trimer and 1,2,4-trithiolane of adamantanethione.

The molecules of dispiro[1,3-dithietane-2,2':4,2"-diadamantane], C(20)H(28)S(2), have crystallographic C(i) symmetry, as well as local D(2h) symmetry, and a planar 1,3-dithietane ring. The molecules of trispiro[1,3,5-trithiane-2,2':4,2":6,2"'-triadamantane], C(30)H(42)S(3), have approximate C(2) symmetry and the 1,3,5-trithiane ring has a twist-boat conformation. The C-S-C bond angles within the ring are about 8 degrees larger than observed in most related 1,3,5-trithiane structures. In dispiro[1,2,4-trithiolane-3,2':5,2"-diadamantane], C(20)H(28)S(3), the molecules have local C(2) symmetry and the 1,2,4-trithiolane ring has a half-chair conformation.

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PubMed1996

1,3-Dipolar Activity in Cycloadditions of an Aliphatic Sulfine(,)(1).

2,2,4,4-Tetramethyl-3-thioxocyclobutanone S-oxide (4) combines with diaryl thioketones at room temperature furnishing spiro-1,2,4-oxadithiolanes 6 in equilibrium reactions. Compound 6a was oxidized to the cis-S,S-dioxide 9, the structure of which was established by X-ray analysis. These are the first unequivocal 1,3-cycloadditions of thione S-oxides (sulfines) which possess an allyl anion type MO; cycloadditions to the C=S bond of sulfines as dipolarophile and dienophile had been described before.

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