Synthese und Eigenschaften der Di‐tert‐butylphosphide [M(PtBu2)2]2 (M = Zn,Hg) und [Cu(PtBu2)]4

Syntheses and Properties of Di‐tert‐butylphosphides [M(PtBu₂)₂]₂ (M = Zn, Hg) and [Cu(PtBu₂)]₄ The phosphides [M(PtBu₂)₂]₂ (M = Zn, Hg) and [Cu(PtBu₂)]₄ are accessible from reaction of LiPtBu₂ with ZnI₂, HgCl₂ and CuCl, respectively. [M(PtBu₂)₂]₂ (M = Zn, Hg) are dimers in the solid state. X‐ray structural analyses of these phosphides reveal that [M(PtBu₂)₂]₂ (M = Zn, Hg) contain four‐membered M₂P₂‐rings whereas [Cu(PtBu₂)]₄ features a planar eight‐membered Cu₄P₄‐ring. Degradation reaction of LiPtBu₂(BH₃) in the presence of HgCl₂ results in the dimeric phosphanylborane BH₃ adduct [tBu₂PBH₂(BH₃)]₂. X‐ray quality crystals of [tBu₂PBH₂(BH₃)]₂ (monoclinic, P2₁/n) are obtained from a pentane solution at 6 °C. According to the result of the X‐ray structural analysis, the O₂‐oxidation product of [Hg(PtBu₂)₂]₂, [Hg{OP(O)(tBu)OPtBu₂}(μ‐OPtBu)]₂, features in the solid state structure two five‐membered HgP₂O₂‐rings and a six‐membered Hg₂P₂O₂‐ring. Herein the spiro‐connected Hg atoms are member of one five‐membered and of the six‐membered ring.     

(PPh4)2[Cl2Re(N3S2)(μ‐NSN)(μ‐N≡ReCl3)]2 – ein Rhenium(VII)‐Komplex mit einer Nitrido‐, einer Dinitridosulfato(II)‐ und einer Rhena‐3,5‐dithia‐2,4,6‐triazino‐Funktion

(PPh₄)₂[Cl₂Re(N₃S₂)(μ‐NSN)(μ‐N≡ReCl₃)]₂ – a Rhenium(VII) Complex with a Nitrido, a Dinitridosulfato(II), and a Rhena‐3,5‐dithia‐2,4,6‐triazino Function The title compound has been prepared from PPh₄[Re^VIICl₄(NSCl)₂] with N(SiMe₃)₃ in dichloromethane solution to give red‐brown single crystals, which were suitable for a crystal structure determination. As a by‐product PPh₄[ReNCl₄] is formed. (PPh₄)₂[Cl₂Re^VII(N₃S₂)(μ‐NSN)(μ‐N≡Re^VIICl₃)]₂ ( 1 ): Space group P2₁/c, Z = 2, lattice dimensions at –80 °C: a = 1280.8(2), b = 1017.5(1), c = 2467.8(3) pm, β = 95.04(1)°, R = 0.049. The complex anion of 1 consists of a planar ReN₃S₂‐heterocycle which is connected with the second rhenium atom by a μ‐nitrido bridge as well as by a μ‐dinitridosulfato(II) ligand to form a planar Re₂(N)(NSN) six‐membered heterocycle. This [Cl₂Re(N₃S₂)(μ‐NSN)(μ‐N≡ReCl₃)]^– unit dimerizes via one of the N‐atoms of the (NSN)^4– ligand to give a centrosymmetric Re₂N₂ four‐membered ring.     

Bildung eines Amin‐stabilisierten sechsgliedrigen Co2S4‐Heterocyclus: Synthese und Struktur eines ungewöhnlichen zweifach μ‐η1 : η1‐Disulfid‐verbrückten binuklearen Übergangsmetallkomplexes

The Formation of an Amine Stabilized Co₂S₄ Heterocycle: Structure and Synthesis of a Rare Example of a Double μ‐η¹ : η¹ Disulfido Bridged Binuclear Metal Complex Treatment of Co(BPh₄)₂ · 6 MeCN and Co(ClO₄)₂ · 6 MeCN with S₂^2– or S₄^2– in the presence of the macrocyclic tetraaza ligand 1,4,8,12‐tetraazacyclopentadecane ([15]aneN₄) afforded the new binuclear cobalt sulfur compounds [Co(μ‐S₂)([15]aneN₄)]₂[BPh₄]₂ ( 1 ) and [Co(μ‐S₂)([15]aneN₄)]₂[ClO₄]₂ ( 2 ), respectively, in which two cobalt atoms are bridged by two μ‐η¹ : η¹ disulfido groups forming six‐membered Co₂S₄ heterocycles.     

Di‐μ‐sulfido‐bis[diaqua(18‐crown‐6)­barium(II)]–saccharin (1/2)

The mol­ecule of the title compound {systematic name: di‐μ‐sulfido‐bis[di­aqua(1,4,7,10,13,16‐hexaoxa­cyclo­octade­cane‐κ⁶O)barium(II)] bis­[1,2‐benzisothiazol‐3(2H)‐one 1,1‐dioxide]}, [Ba₂S₂(C₁₂H₂₄O₆)₂(H₂O)₄](C₇H₅NO₃S)₂, lies on an inversion centre. The Ba^II atom encapsulated by the 18‐crown‐6 ring is coordinated by the six O atoms of the crown, two water O atoms and two bridging S atoms. The four‐membered ring composed of the Ba^II atoms and the bridging S atoms makes a dihedral angle of 67.1 (1)° with the crown‐ether ring. The aromatic ring system of the saccharin moiety is essentially planar. The packing is built up from layers of the mol­ecules and is stabilized by three intermolecular O—H?O hydrogen bonds.     

The twinned crystal structure of μ‐2,2′‐bipyrimidine‐1κ2N1,N1′:2κ2N3,N3′‐bis­{tris­[4,4,4‐trifluoro‐1‐(2‐thienyl)butane‐1,3‐dionato‐κ2O,O′]terbium(III)} ethyl acetate solvate

The title compound, [Tb₂(C₂₄H₁₂F₉O₆S₃)₂(C₈H₆N₄)]·C₄H₈O₂, has two terbium(III) centers bridged by the polyazine ligand 2,2′‐bipyrimidine (bpm), which is distorted from planarity by 7.0 (2)°. The terminal ligand 4,4,4‐trifluoro‐1‐(2‐thienyl)­butane‐1,3‐dione (tta) is bidentate, coordinating through the two O atoms, while the bridging ligand is bis‐bidentate, coordinating through four equivalent N atoms. Both the complex and the ethyl acetate solvent mol­ecules are dis­ordered. The structure was refined as a non‐merohedral twin.     

Die Molekül‐ und Kristallstruktur des Rubidium(Dibenzo‐18‐Krone‐6)‐pentaiodids [Rb(C20H24O6)]I5

Molecular and Crystal Structure of Rubidium(dibenzo‐18‐crown‐6)pentaiodide [Rb(C₂₀H₂₄O₆)]I₅ [Rb(Dibenzo‐18‐crown‐6)]₂(I₅)₂ is obtained as dark brown columns by reacting dibenzo‐18‐crown‐6, rubidium iodide, and iodine in a molar ratio of 1 : 1 : 6 in ethanole / dichlormethane (1:1). [Rb(C₂₀H₂₄O₆)]₂(I₅)₂ crystallizes with four formula units per unit cell in the orthorhombic space group Pnma with a = 1725.15(2) pm, b = 1863.76(3) pm and c = 1885.19(3) pm. The crystal structure consists of pentaiodide units I₅^—, which are linked to one another by head‐to‐tail‐contacts. The I₂ units, which stick out of the chain, are twisted against each other, in a way that neither a cis or a trans configuration is formed. By secondary bonding, the iodine atoms form nets of 18‐member planar rings with an almost rectangular form. This net‐like structural element has not been described up to now.     

A novel three‐dimensional copper(II) coordination polymer with 1,4‐bis(1,2,4‐triazol‐1‐ylmeth­yl)benzene and thio­cyanate

In the title complex, poly[copper(II)‐di‐μ₂‐thio­cyanato‐μ₂‐1,4‐bis­(1,2,4‐triazol‐1‐ylmeth­yl)benzene], [Cu(NCS)₂(C₁₂H₁₂N₆)]_n, the Cu^II atom lies on an inversion centre in a tetra­gonally distorted octa­hedral environment. Four N atoms from thio­cyanate and 1,4‐bis­(1,2,4‐triazol‐1‐ylmeth­yl)benzene (bbtz) ligands fill the equatorial positions, and S atoms from symmetry‐related thio­cyanate ligands fill the axial positions. The benzene ring of the bbtz ligand lies about an inversion centre. Single thio­cyanate bridges link the Cu^II atoms into two‐dimensional sheets containing an unprecedented 16‐membered [Cu₄(μ‐NCS‐N:S)₄] ring. The bbtz ligands further link the two‐dimensional sheets into a three‐dimensional network.     

A novel three‐dimensional cadmium(II) coordination polymer incorporating 1,4‐bis­(1,2,4‐triazol‐1‐ylmethyl)­benzene and thio­cyanate

In the title complex, poly[cadmium(II)‐μ₂‐1,4‐bis­(1,2,4‐triazol‐1‐ylmeth­yl)benzene‐di‐μ₂‐thio­cyanato], [Cd(NCS)₂(C₁₂H₁₂N₆)]_n, the Cd^II atom lies on an inversion centre in a distorted octa­hedral environment. Four N atoms from the thio­cyanate and 1,4‐bis­(1,2,4‐triazol‐1‐ylmeth­yl)benzene (bbtz) ligands occupy the equatorial positions, and two S atoms from symmetry‐related thio­cyanate ligands occupy the axial positions. The benzene ring of the bbtz ligand lies about an inversion centre. Single thio­cyanate bridges link the Cd^II atoms into two‐dimensional sheets containing novel 16‐membered [Cd₄(μ‐NCS‐N:S)₄] rings. The bbtz ligands further link these two‐dimensional sheets into an unprecedented covalent three‐dimensional network for the cadmium–thio­cyanate system.     

Diphosphapodanden, [12]‐, [15]‐ und [18]Diphosphacoronanden,Diphosphacryptand‐8 und Alkalimetall‐Komplexe

Diphosphapodands, [12]‐, [15]‐, and [18]Diphosphacoronands, Diphosphacryptand‐8, and Alkali‐Metal Complexes The cyclizing bis‐phosphonium‐salt formation of the open‐chain bis‐phosphine 17a (1,1,7,7‐tetrabenzyl〈P.O.P‐podand‐7〉) with diethylene glycol derived dibromide 13a yields the 12‐membered cyclic bis‐phosphonium salt 20 (4,4,10,10‐tetrabenzyl‐12〈O.P.O.P‐coronand‐4〉‐4,10‐diium dibromide) in yields as high as 50–60%. The 1,1,10,10‐tetrabenzyl〈P.O₂.P‐podand‐10〉 17b forms with 13a the 15‐membered cyclic bis‐phosphonium salt 21 (7,7,13,13‐tetrabenzyl‐15〈O₂.P.O.P‐coronand‐5〉‐7,13‐diium dibromide) with the same high yield. By quaternization of the bis‐phosphine 17b with triethylene glycol derived dibromide 13b , the 18‐membered 7,7,16,16‐tetrabenzyl‐18〈O₂.P.O₂.P‐coronand‐6〉‐7,16‐diium dibromide 24 is obtained in 50% yield, too. The Wittig reaction of the cyclic phosphonium salts with benzaldehyde yields the 12‐, 15‐, and 18‐membered cyclic bis‐benzylphosphine dioxides 9, 10 , and 11 as cis‐ and trans‐isomers beside trans‐stilbene. The 7,13‐dioxido‐7,13‐dibenzyl‐15〈O₂.P.O₂.P‐coronand‐5〉 10 forms a crystalline 1 : 1 Na‐complex 23 , which exists as a dimer. The structure of 23 was established by an X‐ray analysis and spectroscopic data. The 7,16‐dibenzyl‐18〈O₂.P.O₂.P‐coronand‐6〉 28 that is available by reduction of 11 with CeCl₃/LiAlH₄ reacts with triethylene glycol derived dibromide 13b under Ruggly Ziegler‐dilution conditions to give the bicyclic bis‐phosphonium salt 29 (1,10‐dibenzyl〈P[O₂]₃.P‐cryptand‐8〉‐1,10‐diium dibromide) in 18% yield. Again, by the Wittig procedure with benzaldehyde, the 7,16‐dioxido〈P[O₂]₃P‐cryptand‐8〉 12 is obtained as the first diphosphacryptand. The FD‐MS (CH₂Cl₂) of the cyclic bis‐phosphine dioxides 10 – 12 show that they exist as [2M+Na]⁺ complexes. The complex formation constants K_a of 9 – 11 with alkali‐metal cations are studied and compared with the complex formation of corresponding crown ethers.     

NiII and ZnII complexes of the hexadentate macrocyclic ligand cis‐6,13‐di­methyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane‐6,13‐di­amine

The title pendent‐arm macrocyclic hexa­amine ligand binds stereospecifically in a hexadentate manner, and we report here its isomorphous Ni^II and Zn^II complexes (both as perchlorate salts), namely (cis‐6,13‐di­methyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane‐6,13‐di­amine‐κ⁶N)­nickel(II) di­per­chlorate, [Ni(C₁₂H₃₀N₆)]­­(ClO₄)₂, and (cis‐6,13‐di­methyl‐1,4,8,11‐tetraaza‐cyclo­tetra­decane‐6,13‐di­amine‐κ⁶N)­zinc(II) di­per­chlorate, [Zn(C₁₂H₃₀N₆)]­(ClO₄)₂. Distortion of the N—M—N valence angles from their ideal octahedral values becomes more pronounced with increasing metal‐ion size and the present results are compared with other structures of this ligand.     

Bis(5‐hydroxy‐2‐hydroxy­methyl‐4‐pyrone‐κ2O4,O5)bis(2‐hydroxy­methyl‐5‐oxido‐4‐pyrone‐κ2O4,O5)­calcium(II) tetrahydrate

In the title compound, [Ca(C₆H₅O₄)₂(C₆H₆O₄)₂]·4H₂O, which is a kojic acid–Ca²⁺ complex, the Ca atom is on a twofold axis and is octacoordinated by O atoms from four pyrone ligand mol­ecules. The hydroxyl and ketone O atoms of each ligand form a five‐membered chelate ring with the Ca atom. The crystal structure is stabilized by partial stacking and O—H?O hydrogen bonds.     

1,14‐Dioxa‐5,10‐di­aza‐2,3:12,13‐dibenzo­cyclo­octadeca‐2,12‐diene monohydrate

The title compound, C₂₂H₃₀N₂O₂·H₂O, is an 18‐membered di­aza‐crown ether ligand containing two ether O and two aza N atoms. In the macrocyclic ring, the mean N⋯O distance is 4.526 (4) Å. The macrocyclic inner‐hole size, estimated as twice the mean distance of the donor atoms from their centroid, is ∼2.29 Å.     

Polymorph of Dibenzo‐24‐Crown‐8 and its Mercury Complex

Dibenzo‐24‐crown‐8 is studied herein as a flexible ligand able to adopt different conformations, as well as for the complexation of mercury. The recrystallization of dibenzo‐24‐crown‐8 (DB24C8) from dry THF gives a new polymorphic structure of this ligand. This new structure is described and compared to the literature compound. Additionally, coordination of this ligand to mercury iodide HgI₂ is studied.     

Synthese und Kristallstrukturen der Nitrido‐Chloro‐Molybdate [Mg(THF)4{NMoCl4(THF)}2] · 4 CH2Cl2 und [Li(12‐Krone‐4)(NMoCl4)]2 · 2 CH2Cl2

Syntheses and Crystal Structures of the Nitrido‐chloro‐molybdates [Mg(THF)₄{NMoCl₄(THF)}₂] · 4 CH₂Cl₂ and [Li(12‐Crown‐4)(NMoCl₄)]₂ · 2 CH₂Cl₂ Both the title compounds as well as [Li(12‐crown‐4)₂]⁺MoNCl₄^– were made from MoNCl₃ and the chlorides MgCl₂ and LiCl, respectively, in dichloromethane suspensions in the presence of tetrahydrofuran and 12‐crown‐4, respectively. They form orange‐red moisture‐sensitive crystals, which were characterized by their IR spectra and partly by crystal structure analyses. [Mg(THF)₄{NMoCl₄(THF)}₂] · 4 CH₂Cl₂ ( 1 ): space group C2/m, Z = 2, lattice dimensions at –50 °C: a = 1736.6(1), b = 1194.8(1), c = 1293.5(2) pm; β = 90.87(1)°; R₁ = 0.037. In 1 the magnesium ion is coordinated octahedrally by the oxygen atoms of the four THF molecules and in trans‐position by the nitrogen atoms of the two [N≡MoCl₄(THF)]^– ions. [Li(12‐crown‐4)(NMoCl₄)]₂ · 2 CH₂Cl₂ ( 2 ): space group P 1, Z = 1, lattice dimensions at –70 °C: a = 930.4(1), b = 957.9(1), c = 1264.6(1) pm; α = 68.91(1)°, β = 81.38(1)°, γ = 63.84(1)°; R₁ = 0.0643. 2 forms a centrosymmetric ion ensemble in the dimeric cation of which, i. e. [Li(12‐crown‐4)]₂²⁺, the lithium ions on the one hand are connected to the four oxygen atoms each of the crown ether molecules in a way not yet known; and in addition, each of the lithium ions enters into a intermolecular Li–O bond with neighboring crown ether molecules under formation of a Li₂O₂ four‐membered ring. The two N≡MoCl₄^– counterions are loosely coordinated to one oxygen atom each of the crown ether molecules with Mo–O distances of 320.2 pm.     

Three one‐dimensional coordination polymers based on 1,1′‐bis(pyridin‐4‐ylmethyl)‐2,2′‐bi‐1H‐benzimidazole and HgX2 (X = Cl,Br and I)

A new 2,2′‐bi‐1H‐benzimidazole bridging organic ligand, namely 1,1′‐bis(pyridin‐4‐ylmethyl)‐2,2′‐bi‐1H‐benzimidazole, C₂₆H₂₀N₆, L or (I), has been synthesized and used to create three new one‐dimensional coordination polymers, viz.catena‐poly[[dichloridomercury(II)]‐μ‐1,1′‐bis(pyridin‐4‐ylmethyl)‐2,2′‐bi‐1H‐benzimidazole], [HgCl₂(C₂₆H₂₀N₆)]_n, (II), and the bromido, [HgBr₂(C₂₆H₂₀N₆)]_n, (III), and iodido, [HgI₂(C₂₆H₂₀N₆)]_n, (IV), analogues. Free ligand L crystallizes with two symmetry‐independent half‐molecules in the asymmetric unit and each L molecule resides on a crytallographic inversion centre. In structures (II)–(IV), the L ligand is also positioned on a crystallographic inversion centre, whereas the Hg centre resides on a crystallographic twofold axis. Compound (I) adopts an anti conformation in the solid state and forms a two‐dimensional network in the crystallographic bc plane viaπ–π and C—H...π interactions. The three Hg^II coordination complexes, (II)–(IV), have one‐dimensional zigzag chains composed of L and HgX₂ (X = Cl, Br and I), and the Hg^II centres are in a distorted tetrahedral [HgX₂N₂] coordination geometry. Complexes (III) and (IV) are isomorphous, whereas complex (II) displays an interesting conformational difference from the others, i.e. a twist in the flexible bridging ligand.     

The layered compound poly[μ2‐4,4′‐bipyridyl‐di‐μ2‐chlorido‐mercury(II)]

The title compound, [HgCl₂(C₁₀H₈N₂)]_n, features two‐dimensional [HgCl₂(4,4′‐bipy)]_n neutral networks (4,4′‐bipy is 4,4′‐bipyridine), based on an octahedral Hg atom coordinated by four μ₂‐Cl atoms and two μ₂‐4,4′‐bipy ligands in trans positions, yielding a HgCl₄N₂ octahedron. The structure has mmm symmetry about the Hg atoms, with most of the atoms on at least one mirror plane, but the unsubstituted C atoms of the 4,4′‐bipy rings are disordered across a mirror plane. Photoluminescent investigations reveal that the title compound displays a strong emission in the green region, which probably originates from a ligand‐to‐ligand charge‐transfer transition.     

Synthese und Struktur der Cobalt(III)-Komplexe 14gliedriger cis- und trans-N2S2-Dibenzomakrocyclen mit zwei koordinierenden Acetatogruppen

Synthesis and Structure of Cobalt(III) Complexes of 14-Membered cis- and trans-N₂S₂ Dibenzo Macrocycles with two Pendant Acetato Groups The isomeric fourteen membered macrocyclic ligands 6,7,9,15,16,18-hexahydrodibenzo[f,m][1,8]dithia[4,11]diazacyclotetradecine-8,17-diacetic acid-0.5-hydrate (H₂L³), C₂₂H₂₆N₂O₄S₂ · 0.5 H₂O and 6,7,13,15,16,18-hexahydrodibenzo-[e,m][1,4]dithia[8,11]diazacyclotetradecine-14,17-diacetic acid-1.5-hydrate (H₂L⁶), C₂₂H₂₆N₂O₄S₂ · 1.5 H₂O with cis- and trans-N₂S₂ donorsets and two pendant acetato groups form the stable complexes [Co(L³)]ClO₄ · 2 H₂O ( 1 ) and [Co(L⁶)]ClO₄ · H₂O ( 2 ). Co(III) is octahedrally coordinated herein to all six donor centers of the respective ligand. The macrocyclic rings are folded. The metal ions are located outside the macrocyclic cavity. The mean Co? N, Co? O and Co? S distances are 196, 190 and 224 pm, respectively. Crystal data: 1 , monoclinic, space group C2/c, a = 3 797.7(9), b = 763.8(3), c = 2 207.0(7) pm, β = 123.17(2), Z = 8, 3 445 reflections, R(R_w) = 0.072(0.070); 2 , monoclinic, space group C2/c, a = 3 197.1(6), b = 880.4(2), c = 1 890.6(4) pm, β = 112,19(3)°, Z = 8, 4 415 reflections, R(R_w) = 0.062(0.064).     

Pb(18‐crown‐6)Cl2 and Hg(18‐crown‐6)I2: Molecular Dihalides Trapped in a Crown Ether

Pb(18‐crown‐6)Cl₂ and Hg(18‐crown‐6)I₂ are obtained as transparent colourless crystals of needle and hexagonal shape, respectively, by isothermal evaporation of their dichloromethane solutions. Pb(18‐crown‐6)Cl₂ crystallizes with the trigonal crystal system [ , no. 148, a = b = 1176.3(2), c = 1191.8(3) pm, V = 1428.2(5) 10⁶·pm³, Z = 3] whereas Hg(18‐crown‐6)I₂ crystallizes with the orthorhombic crystal system (Pnma, no. 62, a = 1613.9(2) pm, b = 2822.2(5) pm, c = 841.3(1) pm, V = 3832(1)10⁶·pm³, Z = 8). Both compounds are characterized by linear MX₂ (HgI₂ or PbCl₂) molecular units which are encrypted by the crown ether. In both cases, the divalent metal ion resides in the middle of the crown ether resulting in a hexagonal bipyramidal coordination environment for the metal cations. The molecular symmetry comes close to D_3d. Hg(18‐crown‐6)I₂ and Pb(18‐crown‐6)Cl₂ differ in the way the single MX₂@18‐crown‐6 units are packed. Whereas the Hg(18‐crown‐6)I₂ molecules are arranged in a (distorted) cubic closest packing, the Pb(18‐crown‐6)Cl₂ molecules adopt a hexagonal closest packing.     

catena‐Poly[[[μ‐1,3‐bis(diphenylphosphanyl)propane‐κ2P:P′][O‐ethyl (4‐methoxyphenyl)phosphonodithioato‐κ2S,S′]silver(I)] chloroform monosolvate]

Reaction of a mixture of AgOAc, Lawesson's reagent [2,4‐bis(4‐methoxyphenyl)‐1,3‐dithiadiphosphetane‐2,4‐disulfide] and 1,3‐bis(diphenylphosphanyl)propane (dppp) under ultrasonic treatment gave the title compound, {[Ag(C₉H₁₂O₂PS₂)(C₂₇H₂₆P₂)]·CHCl₃}_n, a novel one‐dimensional chain based on the in situ‐generated bipodal ligand [ArP(OEt)S₂]⁻ (Ar = 4‐methoxyphenyl). The compound consists of bidentate bridging 1,3‐bis(diphenylphosphanyl)propane (dppp) and in situ‐generated bidentate chelating [ArP(OEt)S₂]⁻ ligands. The dppp ligand links the [Ag{ArP(OEt)S₂}] subunit to form an achiral one‐dimensional infinite chain. These achiral chains are packed into chiral crystals by virtue of van der Waals interactions. No π–π interactions are observed in the crystal structure.     

Preparation and structural analysis of (±)‐cis‐ethyl 2‐sulfanylidenedecahydro‐1,6‐naphthyridine‐6‐carboxylate and (±)‐trans‐ethyl 2‐oxooctahydro‐1H‐pyrrolo[3,2‐c]pyridine‐5‐carboxylate

Bicycle ring closure on a mixture of (4aS,8aR)‐ and (4aR,8aS)‐ethyl 2‐oxodecahydro‐1,6‐naphthyridine‐6‐carboxylate, followed by conversion of the separated cis and trans isomers to the corresponding thioamide derivatives, gave (4aSR,8aRS)‐ethyl 2‐sulfanylidenedecahydro‐1,6‐naphthyridine‐6‐carboxylate, C₁₁H₁₈N₂O₂S. Structural analysis of this thioamide revealed a structure with two crystallographically independent conformers per asymmetric unit (Z′ = 2). The reciprocal bicycle ring closure on (3aRS,7aRS)‐ethyl 2‐oxooctahydro‐1H‐pyrrolo[3,2‐c]pyridine‐5‐carboxylate, C₁₀H₁₆N₂O₃, was also accomplished in good overall yield. Here the five‐membered ring is disordered over two positions, so that both enantiomers are represented in the asymmetric unit. The compounds act as key intermediates towards the synthesis of potential new polycyclic medicinal chemical structures.