Antoni Konitz

Contributions to the chemistry of silicon–sulfur compounds. Part 75. Cobalt(II) tri-tert-butoxysilanethiolates. Synthesis, properties, crystal and molecular structures of [Co{SSi(OtBu)3}2(L)] and [Co{SSi(OtBu)3}2(L)2] type complexes with monodentate nitrogen ligands

Abstract The title heteroleptic neutral cobalt(II) tri-tert-butoxysilanethiolate complexes with monodentate nitrogen bases (L) as additional ligands have been prepared by the reactions of [Co{μ-SSi(OtBu)3}{SSi(OtBu)3}(NH3)]2 (1) with respective bases. For pyridine both types have been prepared — with two (2) or one (3) nitrogen ligand bonded to cobalt(II). [Co{SSi(OtBu)3}2(L)] complexes have been obtained also with 2-picoline (5), 2,4-lutidine (6), 3,5-lutidine (7), and [Co{SSi(OtBu)3}2(L)2] also with N-methylimidazole (8) and morpholine (9). Molecular and crystal structures of the six compounds have been determined by single-crystal X-ray structural analysis. In 3, 5 and 7 three-coordinated cobalt(II) seems to interact very weakly with two oxygen atoms from two Si(OtBu)3 moieties approaching highly distorted trigonal bipyramidal geometry. Compounds 2, 8 and 9 have distorted tetrahedral structures. Both types of complexes gave characteristic electronic spectra, similar within each type.

Cobalt(II) and Cobalt(III) Tri-tert-butoxysilanethiolates. Synthesis, Properties, Crystal and Molecular Structures of [Co{μ-SSi(OBut)3}{SSi(OBut)3}(NH3)]2 and [Co{SSi(OBut)3}2(NH3)4][SSi(OBut)3] Complexes

The heteroleptic neutral tri-tert-butoxysilanethiolate of cobalt(II) incorporating ammonia as additional ligand (1) has been prepared by the reaction of a cobalt(II) ammine complex with tri-tert-butoxysilanethiol in water. Complex 1, dissolved in hexane, undergoes oxidation in an ammonia saturated atmosphere to the ionic cobalt(III) compound 2. Molecular and crystal structures of 1 and 2 have been determined by single crystal X-ray structural analysis. 1 forms a dimeric molecule [Co{μ-SSi(OBut)3}{SSi(OBut)3}(NH3)]2 with a folded central Co2S2 ring and distorted tetrahedral ligand arrangement at both CoII atoms (CoNS3 core). The product 2 is composed of the octahedral CoIII complex cation [Co{SSi(OBut)3}2(NH3)4]+ and the tri-tert-butoxysilanethiolate anion. Within the crystal two pairs of ions interact by hydrogen bonds forming well separated entities. 1 and 2 are the first structurally characterized cobalt thiolates where metal is also bonded to ammonia and 2 is the first cobalt(III) silanethiolate. Beitrage zur Chemie der Silicium-Schwefel Verbindungen. 74. Cobalt(II) und Cobalt(III) Tri-tert-butoxysilanthiolate. Darstellung, Eigenschaften, Kristall- und Molekulstrukturen von [Co{μ-SSi(OBut)3}{SSi(OBut)3}(NH3)]2 und [Co{SSi(OBut)3}2(NH3)4][SSi(OBut)3] Das heteroleptische, neutrale, als zusatzlichen Liganden Ammoniak enthaltende Cobalt(II)-tri-tert-butoxysilanthiolat (1) wurde bei der Umsetzung von Tri-tert-butoxysilanthiol mit einem Cobalt–Ammin-Komplex in wasseriger Losung erhalten. Verbindung 1, aufgelost in Hexan, oxidiert sich in einer mit Ammoniak gesattigen Atmosphare zum ionischen Cobalt(III)-Komplex 2. Die Molekul- und Kristallstrukturen von 1 und 2 wurden rontgenographisch bestimmt. 1 bildet ein dimeres Molekul [Co{μ-SSi(OBut)3}{SSi(OBut)3}(NH3)]2 mit einen gefaltenen Co2S2 Ring und einer fast tetraedrischen Anordnung der Liganden an beiden CoII-Atomen (CoNS3 Rumpf). 2 ist ionisch aufgebaut mit einem oktaedrischen CoIII-Kation [Co{SSi(OBut)3}2(NH3)4]+ und einem Tri-tert-butoxysilanthiolat-Anion. Im Kristall sind zwei Paare dieser Ionen durch Wasserstoffbrucken zu isolierten Einheiten gebunden. 1 und 2 sind die ersten strukturell charakterisierten Cobalt-Thiolate, in welchen Cobalt noch an Ammoniak gebunden ist. Verbindung 2 ist das erste Cobalt(III)-Silanthiolat.

Zinc(II) Tri-tert-butoxysilanethiolates. Synthesis, Properties, Crystal and Molecular Structures of [Zn{SSi(OBut)3}2(NH3)L] (L = 2-Picoline or 2,4-Lutidine) and [Zn{SSi(OBut)3}2(NH3)2] · MeCN Complexes

[Zn{SSi(OBut)3}2(NH3)]2 (1) reacts with 2-picoline or 2,4-lutidine (L) without elimination of ammonia giving stable monometallic complexes [Zn{SSi(OBut)3}2(NH3)L] (3 and 4), with two different nitrogen ligands bonded to the metal center. Reaction of (ButO)3SiSH with zinc di(acetylacetonate) in ammonia atmosphere leads to the complex with two ammine ligands [Zn{SSi(OBut)3}2(NH3)2] · MeCN (5). Molecular and crystal structures of 3, 4 and 5 have been determined by the single crystal X-ray structural analysis. All have distorted tetrahedral geometry. The presence of ammonia gives rise to hydrogen bonds, different in all three cases. 3, 4, and 5 are the first examples of structurally characterized ammine ligated zinc thiolates. Beitrage zur Chemie der Silicium–Schwefel Verbindungen. 76. Zink(II) Tri-tert-butoxysilanthiolate. Darstellung, Eigenschaften, Kristallund Molekulstrukturen von [Zn{SSi(OBut)3}2(NH3)L] (L = 2-Picolin oder 2,4-Lutidin) und [Zn{SSi(OBut)3}2(NH3)2] · MeCN [Zn{SSi(OBut)3}2(NH3)]2 (1) reagiert mit 2-Picolin oder 2,4-Lutidin (L) ohne Eliminierung von Ammoniak unter Bildung von stabilen monometallischen Komplexen [Zn{SSi(OBut)3}2(NH3)L] (3 und 4), mit zwei verschiedenen stickstoffhaltigen Liganden am Metall-Zentrum. Eine Umsetzung von (ButO)3SiSH mit Zink-Acetylacetonat in einer Atmosphare von Ammoniak ergab einen Komplex mit zwei Ammoniak-Liganden [Zn{SSi(OBut)3}2(NH3)2] · MeCN (5). Die Molekul- und Kristallstrukturen von 3, 4 und 5 wurden rontgenographisch bestimmt. Alle Verbindungen zeigen eine Abweichung von einer tetraedrischen Geometrie. Die Anwesenheit von Ammoniak fuhrt zu Wasserstoffbruckenbindungen die sich in alle drei Fallen unterscheiden. Verbindungen 3, 4 und 5 sind die ersten, strukturell charakterisierten Zink-Thiolate in welchen Zink noch an Ammoniak gebunden ist.

Zinc tri-tert-butoxysilanethiolates. Syntheses, properties and crystal and molecular structures of [Zn{μ-SSi(OBut)3}(acac)]2 and [{(ButO)3SiS}(H2O)2Zn{μ-SSi(OBut)3}Zn(acac){SSi(OBut)3}]

Abstract Heteroleptic, neutral tri-tert-butoxysilanethiolates of zinc, incorporating acetylacetonate (1) or acetylacetonate and water (2) as additional ligands, have been prepared by a reaction of zinc acetylacetonate with tri-tert-butoxysilanethiol in acetonitrile and characterized by IR, NMR and MS techniques. Crystal and molecular structures have been determined by single crystal X-ray structural analysis. Both are bimetallic with a distorted tetrahedral ligand arrangement at the zinc and ZnO2S2 core. Complexes 1 and 2 are the first structurally characterized thiolates where the metal is also bonded to acetylacetonate and 2 is the first neutral aqua-ligated zinc thiolate.

Synthesis, X-ray structure and high-resolution NMR spectroscopy of methyl 3-azido-2,3-dideoxy-α-d-arabino-hexopyranoside

The synthesis, crystal structure data and 1H and 13C NMR spectroscopy of methyl 3-azido-2,3-dideoxy-alpha-D-arabino-hexopyranoside (5b) is reported. This compound adopts the 4C1 conformation. Hydrogen-bonded molecules of 5b form helices around the crystallographic 4(1) axis.

Conformational properties and chiroptical spectra of lactams and thiolactams with 2-azabicyclo[2.2.1]heptane, 2- and 3-azabicyclo[3.2.1]octane skeletons

Abstract The CD spectra of several bicyclic lactams and thiolactams were measured in different solvents. The concentration dependence of the spectra observed in hydrocarbon solvents was attributed to shifts in the equilibrium between monomer and hydrogen-bonded dimer forms. The CD of some compounds is characterized by unusually strong Cotton effects resulting from non-planarity of the amide bonds due to internal strain of the bicyclic skeletons. The X-ray crystallographic structures of 2a , c , 3b , d and 4a , b showed different degrees of distortion of the amide or thioamide moieties from planarity, which causes inherent chirality of the chromophores and profoundly affects the Cotton effect sign and magnitude. This distortion also restricts application of the sector rules for prediction of the n–π * CD sign, since they can be used only for compounds with planar chromophores.

X-ray diffraction and high-resolution NMR spectroscopy of methyl 3-azido-2,3-dideoxy-α-d-lyxo-hexopyranoside

The single-crystal X-ray diffraction and high-resolution 1H and 13C NMR spectral data for the title compound are reported. The influence of the ring oxygen atom on the J(1,2e) and J(4,5) coupling constants for 2-deoxy-D-lyxo- and -D-xylo-hexopyranosides is discussed.

Crystal Structure and Lattice Energetics of 10-Methylacridinium Halides

The crystal structures of 10-methylacridinium chloride monohydrate, bromide monohydrate and iodide were determined by X-ray analysis. The compounds crystallize in the triclinic space group, P¯1, with 2 molecules in the unit cell. The molecular arrangement in the crystals revealed that hydrogen bonds (in hydrates) and van der Waals contacts play a significant part in intermolecular interactions. To discover their nature, contributions to the crystal lattice energy arising from electrostatic (the most important since the compounds form ionic crystals), dispersive and repulsive interactions were calculated. Enthalpies of formation of the salts, their stability and susceptibility to decomposition could be predicted from a combination of crystal lattice energies with values of other thermochemical characteristics obtained theoretically or taken from the literature. The role of water in the stabilization of the crystal lattice of the hydrates is also explained. The information gathered has given an insight into the features and behaviour of compounds which can be regarded as models of a large group of aromatic quaternary nitrogen salts.

Synthesis, the crystal structure, and high-resolution NMR spectroscopy of methyl 4-O-acetyl-3-azido-2,3,6-trideoxy-6-iodo-α-d-arabino-hexopyranoside

Selective tosylation followed by acetylation of methyl 3-azido-2,3-dideoxy-alpha-D-arabino-hexopyranoside (1) in pyridine at room temperature affords a mixture of methyl 4-O-acetyl-3-azido-2,3-dideoxy-6-di-O-p-tolylsulfonyl-alpha-D-arabino-hexopyranoside (4) and methyl 3-azido-2,3-dideoxy-4,6-di-O-p-tolylsulfonyl-alpha-D-arabino-hexopyranoside (3). Compound 4 undergoes nucleophilic displacement with sodium iodide in acetic anhydride to give methyl 4-O-acetyl-3-azido-2,3,6-trideoxy-6-iodo-alpha-D-arabino-hexopyranoside (7), whose crystal structure and (1H) and (13)C NMR data are reported. This compound adopts the 4C(1) conformation.

X-Ray diffraction and high resolution NMR analysis of methyl d-glucopyranuronate derivatives

X-Ray diffraction and high resolution 1H and 13C NMR spectral data for methyl 2,3,4,-tri-O-acetyl-alpha-D-glucopyranuronate and methyl (allyl 2,3,4-tri-O-acetyl- beta-D-glucopyranosid)uronate are presented. Both compounds adopt the 4C1 conformation.