On the enhancement of stereoselection by cooperation between chiral auxiliaries. Asymmetric diels-alder reactions with fumaric acid bis ((S)-proline benzyl ester) amide

Abstract Fumaric acid bis ((S)-proline benzyl ester) amide reacts with cyclopentadiene in thermal and Lewis acid catalyzed Diels-Alder reactions to give the cycloadducts with high yields and diastereomeric ratios up to 100:1.

Über Phosphor‐haltige Heterocyclen, II: Molekül‐ und Kristallstruktur von 1,2,3,4,5‐Pentaphenyl‐1λ 5 ‐phosphol‐1‐on

Die Struktur der Titelsubstanz wurde rontgenographisch aus Diffraktometer-Einkristalldaten bestimmt und bis zu einem konventionellen R von 0.076 verfeinert. Der 5-ring besitzt „envelope”-Konformation. Fehlende Planaritat und Bindungslangenverteilung schliesen eine Elektronendelokalisation im λ5-Phospholsystem aus. Das Propellersystem der Phenylsubstituenten bildet eine Cs-symmetrische Doppelschneckenschraube. Die Struktur besteht aus 14-fach koordinierten Molekulen. On Heterocyclic Systems Containing Phosphorus, II: Molecular and Crystal Structure of 1,2,3,4,5-Pentaphenyl-1 λ5-phosphol-1-one The crystal structure of the title compound has been determined from single crystal X-ray data and r…

Über Tetraaryl-methan-analoga in der gruppe 14

The title compounds have been synthesized by Li and Grignard reactions. The crystal structure of Ph3Si-p-Tol has been determined. The substitution of only one phenyl by one p-tolyl group causes only a slight deviation from the ideal S4 symmetry of Ph4Si. Gradual replacement of phenyl by p-tolyl groups leads to increasing low field shifts for all 13C(ipso) atoms. The substitution of the first phenyl group by p-tolyl in Ph4Si and Ph4Sn results in a high field shift both for δ(29Si) (−0.3 ppm) and for δ(119Sn) (−1 ppm). Further replacement shows nearly linear dependencies (Δδ(29Si) = −0.1 ppm, Δδ(119Sn) = + 1.5 ppm per p-tolyl group).

Racemattrennung, Kristallstruktur und histaminartige Wirkung von 4-[1-(2-Aminoethylthio)ethyl]-5-methylimidazol

Es wird die Racemattrennung von 4-[1-(2-Aminoethylthio)ethyl]-5-methylimidazol (1) mittels optisch aktiver Di-O-(p-toluoyl)weinsaure sowie die histaminartige Wirksamkeit der Enantiomeren beschrieben. Von (+)-1 · 2HCl · H2O wurde die Kristallstruktur bestimmt und bis zu einem R-Wert von 0.0483 verfeinert. Danach ist (+)-1R-konfiguriert. Von den beiden Enantiomeren besitzt nur (S)-(−)-1 H1-agonistische Aktivitat. Resolution, Crystal Structure, and Histamine-like Activity of 4-[1-(2-Aminoethylthio)ethyl]-5-methylimidazole The resolution of racemic 4-[1-(2-aminoethylthio)ethyl]-5-methylimidazole (1) using optically active Di-O-(P-toluoyl)tartaric acid as well as the histamine-like activity of t…

Tetra-p-tolyl-verbindungen p-Tol4Si und p-Tol4Ge: Ein beitrag zur konfiguration der tetraaryl-methan-analoga Ar4M (M = C, Si, Ge, Sn, Pb)

Abstract p-Tol4Si and p-Tol4Ge have been obtained from the reaction of p-TolLi with SiCl4 and of p-TolMgBr with GeCl4, respectively. The crystal structures have been determined and compared with those of the homologous compounds p-Tol4Sn and p-Tol4Pb. The latter two molecules (space group I 4 ) exhibit a S4 axis running between the aromatic groups and are shortened along this axis: all four p-Tol groups are closer together than in an undistorted tetrahedron. In the cases of the silane and germane (space group Pc), the tetrahedron is lengthened along one of the bond axes CM: only three of the four p-Tol groups are closer together, and the set up of a special molecular symmetry is blocked. A…

Darstellung und struktur von (EtO)2P(O)CH2Si(Me)2CH2SnMe2Cl—ein sechsringchelat mit sesselkonformation und PO ⋯ Sn(Cl)Me2CH2-trigonaler bipyramide am Lewis-aciden Zinn

Abstract The title compound (EtO)2P(O)CH2Si(Me)2CH2SnMe2Cl (2) has been synthesized by reaction of the new functional Grignard reagent (EtO)2P(O)CH2CH2SiMe2CH2MgCl with Me3SnCl and subsequent treatment with Me2SnCl2. 2 crystallizes in the non-centrosymmetric orthorhombic space group P212121. The structure was refined to a final R-value of 0.0476. The tin atom is pentacoordinated and exhibits a nearly ideal trigonal-bipyramidal coordination (SnCl 2.518(3), Sn ⋯ O 2.371(5) A). This coordination results from a 6-membered chelate involving a chair conformation. The structure of 2 is compared with analogous compounds containing a PO ⋯ Sn- or CO ⋯ Sn-coordination in the first place and a noncy…

Dimeres und Trimers 1-Methyl-1-aza-5-stannabicyclo[3.3.01,5]-octan sulfid [MeN(CH2CH2CH2)2SnS]n, Röntgenstrukturanalyse des Dimeren und Gleichgewicht Dimer-Trimer gemäß 119Sn-NMR und FD-Massenspektrometrie

Abstract The crystal structure of the dimeric title compound has been determined and refined to R = 0.0266. The core of the nearly centrosymmetric dimer is formed by an almost perfect [SnS]2 rectangle (Sn-S 2.39 and 2.51 A). The two sulfur atoms of this rectangle establish the connecting edge of two distorted trigonal bipyramids around the two tin atoms (Sn … N 2.55 A). Solutions of the title compound contain in addition to the dimer (σ(119Sn) = −4.6 ppm) about 20% of the trimer (+ 10.3 ppm). By quick crystallization a mixture of both oligomers can be transferred into the solid state.

Über polygermane

Abstract The germylene Ph2Ge of Ph2GeHCl and Net3 inserts in excess Ph2GeHCl and forms polygermanes Cl(Ph2Ge)nH. This one-pot reaction and subsequent chlorination to Cl(Ph2Ge)nCl has been optimized. Increasing amounts of NEt3 step up the yields of higher polygermanes. The 13C NMR phenyl signals for C(ipso) shift to low field with increasing chain length. The crystal structures of Cl(Ph2Ge)3,4Cl (R = 0.072 and 0.087) have been determined. The position of Cl(Ph2Ge)4Cl is split off by disorder (main molecule 82%, side molecule 18%). Two crystallographically different molecules of the trigermane are present; the ClGe3Cl chain contains anti-gauche and gauche-gauche conformation respectively (d…

Über Chalkogenolate, LXVI. Untersuchungen an cis ‐1,2‐Dicyanäthylen‐1,2‐dithiolaten 4. Kristallstruktur von Bis(methylthio)maleonitril

Die Struktur des Bis(methylthio)maleonitrils (1) wurde rontgenographisch aus Diffraktometer-Einkristalldaten bestimmt und bis zu einem konventionellen R von 0.049 verfeinert. Der (NCCS)2-Teil unterscheidet sich in seinen Dimensionen nicht vom (NCCS)22 -Liganden in Ubergangsmetallkomplexen Die grosere Stabilitat von 1 gegenuber dem Fumarsaure-Isomeren wird diskutiert. Die Struktur besteht aus planaren 1-Schichten parallel zur Flache (101) mit optimaler Packungsdichte der 16-fach koordinierten Molekule. On Chalcogenolates, LXVI. Studies on cis-1,2-Dicyanoethylene-1,2-dithiolates The crystal structure of bis(methylthio)maleonitrile (1) has been determined from single crystal X-ray data and ref…

Kristallstruktur von S,S ′‐Diäthyldithiooxalat (COSC 2 H 5 ) 2

Die Struktur des S,S′-Diathyldithiooxalats wurde aus Rontgenbeugungsdaten, gewonnen mit MoKα-Strahlung bei −60 ± 5°C, berechnet. Die Verbindung kristallisiert monoklin in der Raumgruppe P21/c, Nr. 14, mit den Gitterkonstanten a = 4.760, b = 10.744, c = 10.063 A und β = 121.8°. Die Elementarzelle enthalt zwei Molekule (COSC2H5)2. Diese ordnen sich in Richtung der 21-Achsen symmetrisch zu den Symmetriezentren in 1/2,0,0 und in der Zellmitte. Die Verfeinerung fuhrte zu einem konventionellen R von 0.058. Crystal Structure of S,S′-Diethyl Dithiooxalate (COSC2H5)2 The structure of (COSC2H5)2 was calculated from a data set collected by X-ray diffraction with MoKα-radiation at a temperature of abou…

Über blei-haltige Heterocyclen

Abstract Crystal structures of alternating six-membered rings [Ph2PbS]3-P21/c and [Ph2SnS]3-P21/n have been determined by X-ray methods. Both heterocycles exhibit a C2-symmetric twisted boat conformation with tetrahedral coordination of the metal atoms [dPbS 2.491 A (dSnS 2.401 A, dPbC 2.19 A (dSnC 2.129 A)]. No additional intermolecular contacts have been found. A ring-segment exchange reaction in solution has been observed by NMR. In the resulting equilibrium new cyclic compounds containing both tin and lead atoms with coupling constants 2J(207PbS119Sn) 226 Hz have been detected. FD-mass spectra indicate formation of dimeric molecular units.

Die kristallstruktur von cycloalkanen

An X-ray structure analysis was performed on single crystals of the cycloalkane (CH2)36. The lattice belongs to the space group Aa and is arranged in layers. The unit cell has the dimensions α = 1,033 nm, b = 0,824 nm, c = 4,22 nm, β = 107, 1° and contains four molecules. The molecules consist of two stretched stems which are linked by sharp folds at each end. The folds have the conformation …t(g g t g g) t… lying parallel to the b-axis. Raman measurements suggest that the stems are slightly twisted. A comparison of the homologous series (CH2)n, n = 36, 48, 60, and 72 using X-ray powder methods showed that the (CH2)36-structure, including the fold conformation, is also representative for th…

Über gemischte Gruppe 14—Gruppe 14-Bindungen

Abstract p-Tol6PbSn has been synthesized by reaction of p-Tol3PbLi with p-Tol3SnI in THF/ether (1:2) at −78°C. The crystal structures of p-Tol4Pb (I 4 ) and of p-Tol6Sn2, p-Tol6PbSn and p-Tol6Pb2 have been determined. The three dinuclear compounds crystallize not strickly isomorphous. They exhibit the same space group (R 3 and rather similar unit cell dimensions. Yet according to the solvent of crystallization, two types with differing atomic position parameters can be distinguished (“homoeotypism with differences of parameters” in the definition of Laves). In both types, the individual molecules have a chiral C3-symmetric conformation and the non-chiral unit cell encloses both enantiomers.…

Kristallstruktur, thermische Ausdehnung und Farbwechsel von (Me3Ge)2Sb-Sb(GeMe3)2 und anderen Distibanen

Abstract Single crystals of the distibanes (Me3M)4Sb2 (1: M = Si, 2: M = Ge) are obtained by the oxidation in air of (Me3M)3Sb. The crystal structure of 2 is reported. 2 forms linear chains of distibane molecules in trans conformation with Sb ··· Sb contacts of 386 pm at −110°C and 390 pm at 22°C. The thermal expansion of crystals of 2 and (Me3Sn)4Sb2 (3) has been determined. UV-VIS spectra of 1–3, Me4Sb2 (4), Et4Sb2 (5), and Ph4Sb2 (6) in different phases have been recorded. The spectra of 1–5 are consistent with the visible colour changes.

Molekül- und kristallstruktur von hexamethylcyclo-tristannaselenan [(CH3)2SnSe]3

Hexamethylcyclotristannaselenane [(CH3)2SnSe]3 forms tetragonal crystals, space groups P41212, with a  986.5(2), c  1769.7(4) pm, Z  4. The complete X-ray structural analysis (two independent determinations) shows the six-membered ring to have a twist-boat conformation similar to [(CH3)2SnS]3. The SnSe2C2 tetrahedra are only slightly distorted, the mean bond distances being SnSe 253.1 (251.7⋯254.0(4)) pm, Sn C 2.13 (2.09⋯2.17(3)) pm. Conformational details are discussed.

Ring size control in diorganotin sulphides by intramolecular SnN coordination

Abstract The synthesis of intramolecularly coordinated organotin sulphides, [(Me2N CH2CH2CH2)2SnS]n (1) and [Me2NCH2CH2CH2Sn(Ph)S]n (2), is described. Compounds 1 and 2 are dimers in chloroform solution (n = 2). Compound 1 forms a centrosymmetric dimer with a planar rectangular Sn2S2 four-membered ring in its centre. The tin atoms show a distorted trans-cis-cis octahedral coordination by 2C, 2N and 2S. The tin-nitrogen distances are 2.810(3) and 3.158(5) A. Compound 1 can be regarded as a model substance for nucleophilic attack at penta-coordinate tin centres. Although the degree of intramolecular coordination of nitrogen to tin is temperature dependent, the four-membered Sn2Sn2 ring remain…

Über tetraaryl-methan-analoga in der gruppe 14

Abstract The title compounds have been synthesized by Grignard reactions or pyrolysis of diplumbanes respectively. The crystal structures of m -Tol 4 Pb and Ph 4 Pb (redetermination) have been determined. All eight compounds (Ph/Tol) 4 (Sn/Pb) are S 4 symmetric and contracted along this unique axis. The 13 C-NMR chemical shifts and the couplings 1 J ( 119 Sn/ 207 Pb 13 C) as well depend additively upon the methyl substituents. The ratios 1 K ( 207 Pb 13 C): 1 K ( 119 Sn 13 C) of the reduced coupling constants are all near to 1.61; a comparison with values from the literature for alkyl, alkenyl and alkinyl substituents is given. The ratio δ( 207 Pb):δ( 119 Sn) results in 2.28. IR (700 dow…

Darstellung, Kristallstruktur und Wirkung von 2-Methyl-3-(4-oxo-3-phenyl-thiazolidin-2-ylidenamino)-4-(3H)-chinazolinon

Quinazolinones. 1. Preparation, crystal structure and action of 2-methyl-3-(4-oxo-3-phenyl-thiazolidine-2-ylidenamino)-4-(3H)- quinazolinone.

On heterocyclic systems containing bismuth(III) 2. Eight-membered heterocycles Cl/Br/I-M(CH2CH2CH2)2X with lewis acidic group 15 atoms M  As, Sb, Bi and donor atoms X  NR, S: a contribution to the value of the electronegativity of bismuth(III)

Abstract Paths to the ligands (Cl/Br-CH2CH2CH2)2NR/O/S/Se, R  Me, Bz, iPr, iBu, to the diGrignard reagents (Cl/BrMg-CH2CH2CH2)2NR/O/S, R  Me, Bz, iPr, iBu and to the eight-membered group 15 heterocycles (Cl/Br/I-As/Sb/Bi(CH2CH2CH2)2NR/S, R  Me, Bz, iBu are given. 13C-NMR, IR and Raman spectra are discussed; for the compound ClSb(CH2CH2CH2)2NMe the crystal structure analysis is given : the antimony atom is clearly Lewis acidic with ψ-trigonal-bipyramidal coordination and a transannular Sb⋯N interaction of 2.385(2) A. For such a configuration the values of the 13C-NMR chemical shifts of the α-CH2-groups (e.g. Cl-As/Sb/Bi(αCH2CH2CH2)2NMe 34.6, 25.9, 46.6 ppm) display clearly a sequence N > …

Aminosäureester als chirale Hilfsgruppen in Lewis-Säure-katalysierten Umsetzungen elektronenreicher Siloxydiene mit Iminen

Strukturen von [Me4Sb]2[MeSbI4]MeSbI2, und [Me4Sb]I. Darstellung von Me3Sb · MeSbI2 und farbwechsel bei Me4Sb2 · Me2SbBr

Abstract The crystal structures of the complex [Me 4 Sb] 2 [MeSbI 4 ] ( 1 ) and its precursors MeSbI 2 ( 2 ) and [Me 4 Sb]I ( 3 ) are reported. In 1 there are tetrahedral cations and square pyramidal anions with Sb-I distances of 290–320 pm. The structure of 2 contains MeSbI 2 molecules. They associate via iodine bridges to form linear chains with alternating short and long Sb-I distances. The coordination around antimony is distorted tetragonal pyramidal. The tetrahedral coordination of the ions in 3 results in the formation of a wurtzite type structure with antimony-iodine distances of 406 and 435 pm. The novel adducts Me 3 Sb·Me 2 SbI 2 ( 4 ) and Me 2 SbSbMe 2 ·Me 2 SbBr ( 5 ) are formed…

Über polygermane

Abstract The optimum conditions for selectively cleaving off two phenyl groups in Ge2Ph6 by trichloroacetic acid have been determined. Neither trihaloacetic acids nor HCl/AlCl3 nor reactive tetrahalides MCl4 are suitable reagents for cleaving one phenyl group alone. The 13C NMR chemical shifts of functional phenyl-mono- and -digermanes are given. The crystal structure of 1,2-bis(trichloroacetate)tetraphenyldigermane has been determined and refined to R = 0.048. The digermane bond is bridged by both acetates (distances GeGe 239.3(2), GeO 207.3(3) and 231.4(3) pm). The Ge atoms have trigonal bipyramidal coordination.

Über polygermane

Summary Reaction of LiGePh2GePh3 with Cl2GePh2 at −65°C in ether yields n-Ge5Ph12 as the main product, in addition to shorter-chained polygermanes. The analysis of the resulting products and the isolation of the pentagermane was done by HPLC. The crystal structure was determined (R = 0.095). The conformation of the Ge5 chain is antiperiplanar-anticlinal (−179.3 and +114.4°) with mean Ge-Ge distances of 247.6 (central) and 244.3 pm (terminal).

Über polygermane

Abstract The synthesis of GePh4 and Ge2Ph6 by Grignard reaction in THF or ether/toluene leads to the by-products Ge3Ph8 (up to 11%) and Ge4Ph10 (up to 18%) which is dependant on using an excess of Mg. A quantitative analysis of the resulting products by HPLC and a semipreparative separation by column, flash, and HPL chromatography is described. The crystal structures of Ge3Ph8 (R = 0.075) and Ge4Ph10 · 2C6H6 (R = 0.054) have been determined. Ge4Ph10 has Ci symmetry and both chain conformations are well staggered (49–70° for Ge3Ph8, 53–66° for Ge4Ph10). The GeGe distances and GeGeGe angles are 244 pm and 121° (Ge3Ph8), and 246 pm and 118° (Ge4Ph10).

Über Zinn‐haltige Heterocyclen, I. Molekül‐ und Kristallstruktur von 2,2‐Dichlor‐1,3,6,2‐trithiastannaocan

Die Struktur der Titelsubstanz wurde rontgenographisch aus Diffraktometer-Einkristalldaten bestimmt und bis zu einem konventionellen R von 0.024 verfeinert. Der 8-Ring besitzt Wanne-Sessel-Konformation mit transannularer 1,5-Sn···S-Annaherung. Die Koordination am Sn-Atom ist trigonal-bipyramidal mit aquatorialen Abstanden SnS 2.386 und 2.388 A und SnCl 2.348 A und axialen Abstanden SnS 2.760 A und SnCI 2.392 A. Bekannte SnS-Abstande und Koordinationen werden diskutiert. Die Struktur besteht aus 12-fach koordinierten Molekulen. On Heterocyclic Systems Containing Tin, I. Molecular and Crystal Structure of 2,2-Dichloro-1,2,6,2-trithiastannaocane The crystal structure of the title compound has …

Über polygermane

Abstract The optimum conditions for the synthesis of the trigermanes Ge3Ph8 and Ge3Me2Ph6 according to R2GeCl2 + 2 Ph3GeAk (Ak = Li, K) in HMPT have been determined. The main difficulty is to repress a nucleophilic attack of Ph3Ge− at newly formed GeGe bonds. The mass spectrum of Ge3Me2Ph6 shows rearrangements of the GePh3 and Ph/Me groups. The 13C NMR phenyl signals of di-, tri- and tetra-germanes are nearly identical. Ge3Ph8 and Ge4Ph10 transform to the plastically-crystalline state before melting (ΔH 45.3 and 54.9 kJ mol−1). The crystal structure of Ge3Me2Ph6 has been determined. The molecule has C2 symmetry (GeGe 242.9(1) pm, GeGeGe 120.3(1)°).

Über gemischte bindungen in der IV. hauptgruppe

Abstract Reaction of Ph3SnLi with Ph2SiCl2 or Ph2GeCl2 at −78°C in THF yields (Ph3Sn)2SiPh2 (1) and (Ph3Sn)2GePh2 (2). The crystal structure of 1 (R = 0.075) exhibits SnSi distances of 257.2(4) and 257.9(5) pm, an SnSiSn angle of 118.5(2)°, and a central C3SnSiC2SnC3 molecular skeleton with symmetry close to C2. The geminal NMR coupling 2J(119Sn ⋯ 119Sn) in 1, and in a tri-, tetra- and pentastannane series shows a linear correlation to their respective non-bonded d(Sn ⋯ Sn) distances (I(t-Bu2Sn)4I: 20 Hz/496 pm; 1: 724 Hz/443 pm).

Über Germanium‐haltige Heterocyclen, II. Molekül‐ und Kristallstruktur von 2,2‐Dichlor‐1,3,6,2‐trithiagermocan

Die Struktur der Titelsubstanz wurde rontgenographisch aus Diffraktometer-Einkristalldaten bestimmt und bis zu einem koventionellen R von 0.052 verfeinert. Der 8-Ring besitzt Wanne-Sessel-Konformation mit transannularer 1,5-GeS-Annaherung. Die Koordination am Ge-Atom ist trigonal-bipyramidal mit aquatorialen Abstanden GeS 2.191(13) und Ge–Cl 2.149(3) A und axialen Abstanden Ge–S 3.005(3) und Ge–Cl 2.208(3) A. Bekannte Ge–S-Abstande werden diskutiert, und Abstandsbereiche fur Ge – S- und Sn – S-Bindungen verschiedenen Typs werden festgelegt. Die Struktur besteht aus 14-fach koordinierten Molekulen. On Heterocyclic containing Germanium, II. Molecular and Crystal Structure of 2,2-Dichloro-1,3,…

Tetraaryl-methane analogues in group 14—V. Distortion of tetrahedral geometryin terms of through-space π–π and π–σ interactions andNMR sagging in terms of π–σcharge transfer

Abstract 44 members of thecompound series Ph4−nMRn (M=Si, Ge, Sn, Pb; R=o-, m-, p-Tol; n=0–4) were synthesized (15 newcompounds). The crystal structures of Ph3Sn (o-Tol) and PhSn (o-Tol)3 were determined and compared to 16 known structures. Subject to the distanced (M–C), an interplay between through-space π–π repulsion and π–σ attraction leads to either elongated or compressed tetrahedral geometry. 29 Si-, 119 Sn- and 207 Pb-NMR chemical shifts were determined in solution and in the solid state.73 Ge chemical shifts were measured only in solution. Anupfield or downfield sagging of the chemical shifts along each series is rationalized in terms of a π–σcharge transfer which is constrained by…

Über polyplumbane

Abstract Diplumbanes Pb 2 R 3 R′ 3 (R,R′ = Ph, o -Tol, p -Tol) have been synthesized from R 3 PbLi and R′ 3 PbCl at −60°C in THF. Mass, 13 C and 207 Pb NMR spectra of the products exhibit migrations of R, R′ in the transition state (R 3 PbLi + ClPbR′ 3 ) leading to a complex distribution of the substituents (δ( 207 Pb) with respect to PbMe 4 −70 to −95 ppm). The PbPb stretching vibration (100 to 115 cm −1 ) couples with a lattice vibration giving rise to a single intensive Raman line. The crystal structure of Pb 2 Ph 3 ( p -Tol) 3 has been determined and refined to R = 0.155. Two independent molecules are disordered and have identical distribution of the substituents Ph( p -Tol) 2 PbPbPh …

Über polystannane

Abstract The compound I(t-Bu2Sn)4I has been synthesized by controlled cleavage of the related cyclotetrastannane (t-Bu2Sn)4 with iodine in toluene. Both compounds have been investigated by mass, NMR and vibrational spectra. I(t-Bu2Sn)4I: δ(119Snterminal) 67.7, δ(Sncentral) 17.4 ppm; 1J(SnSn) 2199 (terminal-central) and 1575 (central-central), 2J(SnSn) 20 (terminal-central), 3J (SnSn) 307 Hz (terminal-terminal); ν(SnSn) 119, ν(SnI) 167 cm−1. (t-Bu2Sn)4: δ(Sn) 87.4 ppm; ν(SnSn) 125 cm−1. The crystal structure of I(t-Bu2Sn)4I has been determined (R = 0.071): bond lengths SnSn 289.5(1) (terminal-central) and 292.4(1) (central-central), SnI 275.3(1) pm. The conformation of the chain ISn…

Über polygermane

Abstract The crystal structure of octaphenylcyclotetragermane, (Ph 2 Ge) 4 , has been determined and refined to an R value of 0.046. The symmetry of the molecule approximater D 2d . the Ge 4 ring is nearly planar and square (angle of pucker 3.9°, GeGe 246.5(5) pm). The 8 phenyl groups (GeC 196.2(10) pm) are arranged in two distinct sets (“parallel” touching and perpendicular to the Ge 4 ring) which exchange their positions in solution. The packing of the (Ph 2 Ge) 4 molecules in the crystal resembles a cubic body centred sphere packing. The homocyclic series (Ph 2 Ge) n with n  4, 5, 6 shows 13 C NMR signals in CDCl 3 solution monotonic dependent on the endocyclic GeGeGe angles.

Über Germanium‐haltige Heterocyclen, IV. 2,2,4,4,6,6‐Hexaphenyl‐1,3,5‐trioxa‐2,4,6‐trigermacyclohexan, (Ph 2 GeO) 3 , eine monoplanare Zwischenstufe im Pseudorotationskreislauf der Twist‐Wanne‐6‐Ring‐Konformation

Die Titelverbindung 1 wurde durch Hydrolyse von Ph2GeCl2 in acetonischer Losung gewonnen. Die Kristallstruktur wurde bestimmt und bis R = 0.049 verfeinert. Die Konformation des Ge3O3-6-Ringes ist monoplanar und bildet eine mogliche Zwischenstufe einerseits fur die Racemisierung von Twist-Wanne-Enantiomeren und andererseits bei der Sessel-Sessel-Inversion. Ein angeregter Zustand mit umlaufendem Null-Torsionswinkel wird als Alternative zur gangigen Lehrbuchdarstellung dieser Vorgange diskutiert. Die GeOAbstande und GeOGe-Winkel betragen 176–178 pm bzw. 128–130°. Die 1-Molekule sind im Kristall nach Art einer tetragonal-innenzentrierten Kugelpackung mit (10 + 4)-Koordination gepackt. On Hetero…

Über antimon-haltige heterocyclen

Abstract p -Nitrophenyl- and p -tolyl-oxadithia- and trithiastibocanes have been synthesized from the respective aryldichlorostibane and dithiole. The compounds have been characterised by means of 13 C NMR and vibrational spectra (ν(SBS 2 ) 350–320 cm −1 ). The crystal structure of p -nitrophenyltrithiastibocane has been determined ( R = 0.042). The eight-membered ring exhibits a boat-chair conformation. Single-bond distances of SbC and SbS (219, 244 and 245 pm), a 1,5-transannular Sb⋯S interaction (319 pm), and Sb⋯S and Sb⋯O (339 and 353 pm) intermolecular contacts, result in a six-coordinated Sb III (ψ-monocapped octahedral) species. The two additional Sb⋯S distances are in accordance w…

(Me3Sn)2SbSb(SnMe3)2, 1∞-verknüpfte SbSb-Hanteln in einem thermochromen Distiban mit Schweratomgerüst

Abstract Single crystals of the thermochromic distibane (Me 3 Sn) 4 Sb 2 ( 1 ) are obtained by irradiation of (Me 3 Sn) 3 Sb with sunlight. The crystal structure of 1 is reported as linear chains of distibane molecules in trans conformation with Sb ⋯ Sb contacts of 389 ppm. Diffuse reflexion spectra of 1 in the solid state and in solution demonstrate thermochromic effect. The Raman spectrum of solid 1 exhibits strong absorption at 162 cm −1 for ν(Sb 2 ).

Über polygermane

Abstract [(Cl 3 CCOO)Ph 2 Ge] 2 reacts with wet acetone to give Ph 8 Ge 4 O 2 , and with dry H 2 S to give Ph 8 Ge 4 S 2 . With Na 2 S or NaHSe, Ph 4 Ge 2 Cl 2 yields Ph 8 Ge 4 S 2 and Ph 8 Ge 4 Se 2 , respectively. Only Ph 6 Ge 3 S 2 or Ph 6 Ge 3 Se 2 , but no Ph 6 Ge 3 O 2 , can be obtained from a mixture of Ph 4 Ge 2 Cl 2 , Ph 2 GeCl 2 and Na 2 S or NaHSe. The mass spectra show a high stability of the cations Ph 6 Ge 3 S 2 + and Ph 6 Ge 3 Se 2 + . The 13 C NMR phenyl signals for C( ipso ) shift to high field in the series O, S, Se and 6-membered, 5-membered rings. The crystal structures of Ph 8 Ge 4 O 2 ( R = 0.031) and Ph 6 Ge 3 S 2 ( R = 0.036) have been determined. The 6-membered ring…

Amino Acid Esters as Chiral Auxiliary Groups in Lewis Acid Catalyzed Reactions of Electron-rich Siloxydienes with Imines

Über zinn-haltige heterocyclen

Abstract The crystal structure of 2,2,6-trimethyl-1,3-dithia-6-aza-2-stannocane has been determined and refined to R = 0.043. The transannular 1,5-distance Sn ⋯ N = 256.6(6) pm exceeds the respective single bond by 49 pm. A comparison with analogous eight-membered rings exhibits a clear-cut correlation of such differences with angle deformations in the transition tetrahedron to trigonal-bipyramid. The axial distance SnC is 2 pm longer than the equatorial one.

Über gemischte gruppe 14-gruppe 14-bindungen

Abstract The six title compounds have been synthesized from Li/KSi/GePh 3 and chloride precursors in THF, DME or diethyl ether at low temperature. The six compounds crystallize isomorphously in the space group Pbca with ordered arrangement for the four symmetrical cases (SiSi 2.394, SiGe 2.412, GeGe 2.440 A) and statistical alignment for the two asymmetrical chains; angle range 116.5–123.3°. Replacement of Si by Ge atoms leads to low field NMR chemical shifts for 13 C ipso atoms and for directly bonded 29 Si atoms. This is in accordance with an enhanced electronegativity of germanium in comparison with silicon. UV/Vis and IR/Raman data are given.

Über Germanium‐haltige Heterocyclen, I. Darstellung und Charakterisierung der 8‐Ring‐Verbindungen 2,2‐Dichlor‐1,3,6,2‐trithiagermocan und 5,5‐Dichlor‐1,4,6,5‐oxadithiagermocan

Die Darstellung der Titelverbindungen 3 und 4 wird beschrieben. 1H-NMR-, IR-, Raman- und Massenspektren werden zusammen mit den entsprechenden Spektren der analogen Zinnverbindungen 1 und 2 diskutiert. In Losungen der 8-Ringe 1 - 4 besteht ein Gleichgewicht zwischen zwei chiralen Wanne-Sessel-Konformeren uber eine achirale Sessel-Sessel-Konformation. Fur 1 wird ferner eine Berry-Pseudoration am trigonal-bipyramidal koordinierten Sn-Atom angenommen. Versuche zur Darstellung von analogen Si-Verbindungen werden erwahnt. On Heterocyclic Systems Containing Germanium, I. Synthesis and Investigation of the Eighy-membered Rings 2,2-Dichloro-1,3,6,2-trithiagermocane and 5,5-Dichloro-1,4,6,5-oxadithi…

Über Chalkogenocarbonate, XLVI. Darstellung und spektroskopische Eigenschaften einiger Dimethyl‐trichalkogenocarbonate

Methyljodid reagiert mit der wasrigen Losung eines leicht loslichen CSe32−-Salzes zu Dimethyltriselenocarbonat und mit der wasrigen Losung eines leicht loslichen CS2Se2−-Salzes zu einem Gemisch aus Dimethyltrithiocarbonat, S.Se-Dimethyl-dithiomonoselenocarbonat und Se.Se′-Dimethyl-monothiodiselenocarbonat. Alle vier Ester bilden in flussiger Phase ein Gemisch aus cis-cis- und cis-trans-Konformeren. On Chalcogenocarbonates, XLVI. Synthesis and Spectroscopic Data of Some Dimethyl Trichalcogenocarbonates By reaction of methyl iodide with an aqueous solution of a readily soluble salt CSe32− dimethyl triselenocarbonate is obtained and by reaction with an aqueous solution of a readily soluble sal…

Crystal and molecular structure of 10-(4′-N-pyridyl)-5,15,20-triphenylporphinato indium(III) chloride

A study of the metallation of meso 10-(4′-N-pyridyl)-5,15,20-triphenylporphyrin with indium is reported. The crystal structure of the title compound has been determined by single-crystal X-ray diffraction. The complex crystallizes in the space group P 2 1 / n with Z = 4 and a = 10.146(2), b = 16.096(4), c = 20.861(2) A, β = 90.33 (1)° and V = 3407 A 3 . The crystal structure was refined to a conventional r (F) = 0.059 for 6355 out of 8613 reflections having δ( I )/I < 0.5. The indium-chlorine distance is 2.374(2) A, whereas the indium atom lies 0.608 and 0.7214 A from the plane of the four porphyrin nitrogens and the 24-atom porphyrin plane, respectively. The four outer-sphere aromatic subs…

Über Zinn‐haltige Heterocyclen, IV 1) 5,5‐Diphenyl‐1,4,6,5‐oxadithiastannocan, Fixierung eines konformativen Übergangszustandes in der Kristallstruktur

Die Titelverbindung 1f wurde durch Reaktion von Ph2SnCl2 mit dem Dinatriumsalz des Bis(2-mercaptoethyl)ethers gewonnen. Die Kristallstruktur wurde bestimmt und bis R = 0.054 verfeinert. Die Konformation des 8-gliedrigen Heterocyclus liegt im Bereich des Sattelpunktes fur den Ubergang Sessel-Sessel = Wanne-Sessel Konformation. Die Konfiguration um das Sn-Atom liegt zwischen tetraedrischer 4- und trigonal-bipyramidaler 5-Koordination (transannularer Sn···O-Abstand 266.0 (7) pm). On Heterocyclic Systems Containing Tin, IV1) 5,5-Diphenyl-1,4,6,5-oxadithiastannocane, a Conformational Transition State Stabilized in a Crystal Structure The title compound 1f has been synthesized from Ph2SnCl2 and t…

As(III)/Sb(III)/Bi(III)–halide distances and stretching vibrations. An application of the Varshni relationship upon hypervalent group 15 compounds

Abstract A Varshni treatment between stretching frequencies and bond lengths is given for 16 heterocycles of the types Hal–M(SCH 2 CH 2 ) 2 X and Hal–M(CH 2 CH 2 CH 2 ) 2 X (M=As/Sb/Bi, Hal=Cl/Br/I, X=O, S, NR). The intensities of the Raman emissions for the M–Hal bonds increase in the following order: Cl≪Br −1/2 , decrease in the following order: Cl>Br≫I. Practically, the Varshni constants are used to estimate the complementary quantity, stretching frequency or bond length, in 35 cases.

Synthesen und Strukturen von Ethyl‐, Propyl‐, Butyl‐ und Mesitylantimon

Die Enthalogenierung von Alkylantimondibromiden RSbBr2 (R = Et, Pr, Bu) mit Mg in THF fuhrt zu gelben Losungen, die uberwiegend die Antimonfunfringe (RSb)5 neben den Vierringen (RSb)4 enthalten. Die Trimeren (RSb)3 konnen massenspektrometrisch nachgewiesen werden. Beim Entfernen des Losungsmittels bilden sich reversibel die Polymeren (RSb)x (x » 5) in Form schwarzer Festkorper. In den Ringen nehmen die Substituenten R maximale trans-Positionen ein. Die Kristallstruktur von (MesSb)4 · Benzol enthalt linear …Sb4…Sb4…-verknupfte Cyclotetrastiban-Aren-Komplexe mit guter η6-Haptizitat des Benzolmolekuls an eines der vier Sb-Atome (Ringmitte…Sb 3.81 A, Winkel zur Flachennormale 5°). Der Sb4-Ring …

Nucleophilic attack within Ge, Sn and Pb complexes containing Me2N(CH2)(3) - as a potential intramolecular donor ligand

Abstract Thirteen tin compounds LxPhySnClz and LPh2SnPhX (x=1–4, y=0–3, z=0–2, XPh, F, Cl, Br, I, OPh), six germanium compounds LxPhyGeClz and four lead compounds LPh2PbPhX (XPh, Cl, Br, I) containing the potential intramolecular donor LMe2N(CH2)3—have been synthesized by Grignard reactions, redistribution, halogenation, exchange of halide and phenylation. Evidence for 1,5-chelation in which the donor Me2N intramolecularly attacks the Lewis-acidic atoms Ge, Sn or Pb is provided by six crystal structure determinations: Me2N(CH2)3SnPh2Cl, 5; Me2N(CH2)3SnPh2Br, 5a; Me2N(CH2)3SnPh2I, 5b; Me2N(CH2)3SnPh2OPh, 5d; Me2N(CH2)3SnPh3·HCl·H2O. 1a; Me2N(CH2)3PbPh2I, 17b), and by solution 13C, 119Sn a…

Hypervalent tin-organic compounds: Vibrational spectroscopy in the solid as a tool for structure determination

Abstract A full set of IR- and Raman spectra down from 600 cm1 has been determined and assigned for 60 penta- or hexacoordinated tin-compounds in the groups RSn(CH2CH2CH2)3N (R = Cl, Br, I, Me), RR'Sn(MCH2CH2)2X (R,R′ = Cl, Br, I, Me, Ph, M = CH2 S; X = NMe, O, S), RPh2SnCH2CH2CH2NMe2 (R = Cl, Br, I) and RMe2Sn—CHD—COOMe (R = F, Cl, Br, I, Me). In these hypervalent compounds an approach of the donor atom X to the central atom tin outlines a ‘path’ of nucleophilic attack from a tetrahedron to a trigonal bipyramid. Along this ‘reaction path’ the bond lengths of the axial ligand increase continuously while the bond lengths of the equatorial ligands slightly decrease. The number of similar hype…

Über polygermane

Abstract A complete series of 5-membered heterocycles (Ph 2 Ge) 4 X with X = O, S, Se and Te has been prepared and investigated by mass spectra, 13 C NMR spectra and vibrational spectra. The 13 C signals of the phenyl groups in the compounds (Ph 2 Ge) 4 X were compared with the related values in the homocycle (Ph 2 Ge) 5 . Frequency values for the symmetrical and asymmetrical stretching vibrations of the units GeGeGe and GeXGe are given. The crystal structure of the compound (Ph 2 Ge) 4 S has been determined and refined to a R of 0.051. The 5-membered ring Ge 4 S exhibits envelope conformation.

New Insights into the Classic Chiral Grignard Reagent (1R,2S,5R)-Menthylmagnesium Chloride

Über Arsen‐haltige Heterocyclen, I. Molekül‐ und Kristallstruktur von 2‐Chlor‐1,3,6,2‐trithiarsaocan

Die Struktur der Titelsubstanz (2) wurde rontgenographisch aus Diffraktometer-Einkristalldaten bestimmt und bis zu einem konventionellen R von 0.037 verfeinert. Der 8-Ring hat eine deformierte Wannenform mit transannularer 1,5-AsS-Annaherung. 2 ist dissymmetrisch, der wechselseitige Ubergang zwischen den beiden Spiegelbildisomeren wird besprochen. Die Koordination am As-Atom ist ψ-trigonal-bipyramidal mit axialen Abstanden AsCl 2.36 A, AsS 2.72 A und aquatorialen Abstanden AsS 2.25 und 2.26 A. Bekannte AsS-Abstande und Koordinationen werden diskutiert und Standardwerte fur AsS- und SbS-Abstande verschiedenen Bindungstyps ermittelt. 2 bildet ein Modell fur die Blockierung von Enzym-Proteinen…

Über bismut-haltige heterocyclen

Abstract Methyl and phenyl oxadithia and trithiabismocanes have been synthesized from methyl or phenyl diethoxybismutane and the respective dithiol. The light-sensitive compounds have been investigated by mass, vibrational and 13C NMR spectra: ν(BiMe) 470–460, ν(BiS2) 300–240 cm−1; δ(13Me) −12 ppm. The crystal structure of 5-phenyl-1,4,6,5-oxadithiabismocane has been determined (R = 0.056). The eight-membered ring has the chair-chair conformation. Besides three direct bonds (BiPh 225(2), BiS 256.0(2) and 260.2(3) pm) there are one transannular (Bi⋯O 297(1) and two intermolecular contacts (Bi ⋯S 344.0(3) and 350.9(3) pm) to bismuth in resulting a ψ-monocapped octahedral sphere of coordina…

Über zinn-haltige heterocyclen

Abstract A complete series of diphenyl and mixed methyl/chlorine/bromine/iodinephenyl substituted oxadithia- and trithiastannocanes has been prepared by reactions between the respective disodium dithiolates and tin dihalides. The 13C NMR chemical shifts of these compounds and the coupling constants J(119Sn13C) are dependent upon the magnetic anisotropy of the substituents and the bond angles at the tin atom. The crystal structure of 2,2-diphenyl-1,3,6-trithia-2-stannocane has been determined and refined to R = 0.039. The environment of Sn is a monocapped tetrahedron (transannular distance Sn⋯S 324.6(1) pm). This type of coordination, intermediate between a tetrahedron and a trigonal bipyra…

Über polystannane

Abstract The three compounds Ph4Sn2(X3CCO2)2 were synthesized from Ph2SnH2 and X3CCOOH (X = H, Cl) or by cleavage of two phenyl groups in Ph6Sn2 with Stoichiometric amounts of X3CCOOH (X = Cl, F). The crystal structures (R = 0.041, 0.030, 0.058) show that the Ph4Sn2 units are bridged by two isobidentate acetates resulting in five-coordinated tin atoms. Five crystallographically independent centrosymmetric molecules form three distinct conformers. Bonding parameters (compared with Ph6Sn2): distances d(SnSn) 269, 271, 272, 277 pm; NMR couplings (CDCl3 solution) 1J(SnSn) 16870, 9443, 12915, 4480 Hz; stretching vibrations ν(SnSn) 152, 155, 157, 159 cm−. The ion pairs [Ph4Sn2]2+ [(X3CCO2)2]2−…

Synthesis and structural studies of 2-stannyl-substituted ferrocenylmethylamine and -phosphine derivatives 2-Me2RSnFcCH2Y (RMe, Cl; YNMe2, PPh2, P(O)Ph2; FcC10H8Fe)

Abstract 2-(Trimethylstannyl)ferrocenylmethyldiphenylphosphine, 2-Me3SnFcCH2PPh2 (2a), was synthesized from 2-Me3SnFcCH2NMe2 (1a) and Ph2PH. Compound 2a is oxidized with H2O2 to 2-Me3SnFcCH2P(O)Ph2 (3a). Halogenation of 1a and 2a with Me2SnCl2 and 3a with HCl-diethyl ether yields the organotin monochlorides 2-Me3(Cl)SnFcCH2Y ( 1b , Y = NMe 2 ; 2b , Y = PPh 2 3b , Y = P ( O ) Ph 2 ) . Both crystal structure determinations and multinuclear magnetic resonance studies in solution reveal for 1b–3b molecular structures in which the tin atom approaches a trigonal bipyramidal pentacoordination as a consequence of an intramolecular Y Sn interaction. The donor strength of Y increases in the order PPh2

Heterocyclic systems containing tin(IV)—XIII [1]. Possible ceasing or inversion of the structuraltrans influence during the course of a bimolecular nucleophilic attack of a donor group in a series of SnIV rings

Abstract In the series of the heterocycles X[(CH2)3]2SnR2 (16 newly synthesized compounds and two taken from the literature) and in the germanium analog BuiN[(CH2)3]2GeCl2, the donor group X (= NMe, NBz, NBui, NPri, O, S) intramolecularly attacks the Lewis acidic atoms Sn or Ge. Eight structure determinations (and, in addition, 2 taken from the literature) are compared. The nucleophilic attack at Sn is stronger for the ligands R2 =Cl2 than for the more electronegative R2 = (OSiPh3)2. Overall the familiartrans influence holds: simultaneous approach of X and weakening of the ligand R (trans). In three cases of subtly graded donor strength a slight inversion or ceasing is observed: shorter dis…

Über Phosphor‐haltige Heterocyclen I. Kristallstruktur von trans ‐1,6‐Diphenyl‐1λ 5 ,6λ 5 ‐diphosphacyclodecan‐1,6‐dion‐Dihydrat

Die Struktur der Titelsubstanz (2) wurde rontgenographisch bestimmt und bis zu einem konventionellen R von 0.039 verfeinert. 2 ist zentrosymmetrisch. Der 10-Ring besitzt die bei Cyclodecan-Derivaten (3) ubliche Konformation niedrigster Spannungsenergie. 2 und 3 haben vergleichbare Pitzer- und Baeyer-Spannung, die transannularen Wechselwirkungen sind jedoch in 2 verringert. Die geminalen Phenyl- und Oxo-Substituenten stehen beide extra-annular (Phenyl trans-pseudoaxial, Oxo trans-pseudoaquatorial). Mittlerer CP-Abstand 1.804(3) A, PO-Abstand 1.502(3) A. Die Struktur besteht aus uber PO…HOH…OP-Wasserstoffbrucken verbundenen 2-Molekulen. On Heterocyclic Systems Containing Phosphorus, I. Crysta…

Thermische Diels-Alder-Reaktionen mitN-(2-Alkenoyl)-(S)-prolinestern als chiralen Dienophilen in organischen und wäßrigen Reaktionsmedien

Thermal Diels-Alder Reactions with N-(2-Alkenoyl)-(S)-proline Esters as Chiral Dienophiles Cyclopentadiene reacts with N-acryloyl-(S)-proline benzyl and allyl ester in toluene at 0°C to give the bicycloheptene-carboxylic acid amides with a stereoselection of (2S):(2R) = 81:19. In the reactions with the N,N′-fumaroylbis(proline esters) the cycloadducts are formed in high yields and with isomer ratios of up to 97:3. The absolute configuration of N,N′-〈(1R,2R,3R,4S)-bicyclo[2.2.1]hept-5-ene-2,3-diyldicarbonyl〉bis-[(S)-proline benzyl ester] (6 a) has been determined by an X-ray analysis. In the reactions of the acrylamides with cyclopentadiene and of the fumaramides with cyclopentadiene, isopre…

Über gemischte gruppe 14-gruppe 14-bindungen

Abstract The lead-tin compounds o-Tol6PbSn, o-Tol3PbSnPh3 and Mes3PbSnPh3 have been synthesized from Li and halide precursors in THF/ether at low temperatures. The crystal structures of the S4 symmetric o-Tol4Pb and of the three isomorphous title compounds have been determined (d(SnSn) 2.883 (1), d (PbSn) 2.845 (2), d (PbPb) 2.895 (2), A). The long SnSn distance is in accordance with the Raman data for the pairs of p-Tol6/o-Tol6 substituents (ν(SnSn) 131/123, ν(PbSn) 114/114, ν(PbPb) 105/103 cm−1). The sequence of the 119Sn and 207Pb chemical shifts shows clearly a polarity Pbδ−Snδ+ for all lead-tin compounds investigated. The 1J (119Sn207Pb) and 1J(119Sn119Sn) couplings of identi…

Heterocyclic systems containing antimony (III) -VIII . Hypervalency by intramolecular 1,5-chelation Sb · · · N in rings RSb [ (CH2) 3] 2NR′ (NR′ = NMe, NBz, NBui) and comparison to analogous compounds of AsIII, BiIII, GeIV and SnIV

Abstract Eleven antimony compounds RSb [ (CH2) 3] 2 NR′ and eight germanium compounds R2Ge [ (CH2) 3] 2 NR′ (some combinations of R = Cl, I, NCS, OSiPh3, Ph, and NR′ = NMe, NBz, NBui) have been synthesized by diGrignard reactions and subsequent treatment with AgSCN, Ph3SiONa or PhLi. The compounds were compared to 14 Sn, 1 As, 5 Sb and 4 Bi analogues taken from the literature. Evidence is provided for 1,5-chelation Sb · · · N via crystal structure determinations (5+1 (lit) Sb compounds) , 13C- and 29Si-NMR chemical shifts, 12;Sb and 12;I Mossbauer data (11 and 3 Sb compounds, respectively) , cyclic voltammetry (9 Sb compounds) and semi-empirical MO calculations on the Extended Huckel level …