Volume 38, Issue 1

The crystal structures of compounds A 2 X 2 (A=S, Se; X=Cl, Br) contain molecules X-A-A-X with dihedral angles between 83.9° and 87.4°. Three different types of molecular packing are realized: S 2 CI 2 , S 2 Br 2 (α-Se 2 Br 2 ) and β-Se 2 Br 2 (Se 2 Cl 2 ). Details of molecular geometries as well as crystal structures are discussed.

The preparation of the spirocyclic compounds cis-and trans-NP[(NPCl 2 ) 2 NCH 3 ](NSOPh) 2 from cis-and trans-NPCl 2 (NSOPh) 2 is described as well as the synthesis of the inter-mediates. The 31 P NMR data are discussed.

Au 2 (SeO 2 ) 2 O was prepared from gold and excess selenic acid in a sealed tube at 533 K. The crystal structure [Pba2, a = 659.2(2), b = 1183.7(3), c = 399.8(1) pm, Z = 2,R = 0.087] was determined; gold atoms are bridged by oxide ions (lying on twofold axes) and selenite ions. The extended structure consists of polymeric layers parallel to the xy-plane. The light atom positions are inaccurate because of the presence of a heavy atom in a polar space group.

Na 6 CoS 4 crystallizes in the hexagonal space group P 6 3 mc with a = 890.9(2) pm and c = 687.8(2) pm, Z = 2. The crystal structure was determined from four circle diffractometer data and refined to a conventional R-value of 0.020. Na 6 CoS 4 is isotypic with Na 6 ZnO 4 . The crystal structure can be derived from a h.c.p. arrangement of S atoms. Co atoms occupy tetrahedral voids, the resulting CoS 4 -tetrahedra being almost regular with an average Co-S distance of 235 pm. Na atoms occupy tetrahedral and octahedral voids in the ratio 1:1.

{[Cu 3 (3′-GMP) 2 (3′-GMPH) 2 (H 2 O) 5 ]·7H 2 O} n (1) was isolated from an aqueous solution of Cu(NO 3 ) 2 and guanosine 3′-monophosphate at a pH of 4.4. 1 is monoclinic space group C 2 with a = 29.140(7), b = 6.865(5), c = 16.980(7) Å, β = 90.31(3)°, Z = 2, D c = 1.81 g·cm -3 . The structure was refined to R - 0.065 with i?w = 0.060 for 2642 independent reflections. It is disordered about a crystallographic diad axis with one of the copper atoms Cu(2) sited on this axis. This and the other independent copper atom Cu(l) both display square pyramidal geometries. Cu(l) binds N(7) of a guanine base, two phosphate O atoms of nucleotide molecules not symmetry-related to one another and two water oxygens. The guanine base involved in this coordination adopts a syn-conformation relative to the ribose ring with χ CN = -118.5°. Cu(2) is coordinated by four phosphate O atoms of different nucleotide molecules and one water oxygen. The second guanine base, which is not involved in metal binding, displays the anti-conformation relative to the ribose ring.

The monomeric SeOCl 3 - ion, which can be prepared as the tetraphenylarsonium salt from SeOCl 2 and As(C 6 H 5 ) 4 Cl, was structurally characterized by a low-temperature single crystal X-ray diffraction analysis. [As(C 6 H 5 ) 4 ]SeOCl 3 is monoclinic, space group P2 1 /c, with a = 9,332(3), b = 13,761(4), c = 18,985(6) Å, β = 110,97(3)° (at -135 °C), Z = 4; it contains a novel type of ψ-trigonal bipyramidal oxotrichloroselenate(IV) anion which is not associated to dimers or polymer chains as in known structures. The equatorial positions are occupied by doubly bonded oxygen (Se-O 1,601(3) Å) and by one Cl(Se-Cl 2,234(1) Å), the axial Se-Cl bonds (2,430(1) and 2,475(1) Å) being significantly longer. [N(C 2 H 5 ) 4 ]SeOCl 3 , which was obtained as crystals by oxidation of trichloroselenate(II), is triclinic, space group P1̄, with a = 10,607(3), b = 8,950(2), c = 8,862(2) Å, α = 119,79(2)°, β = 101,07(2)°, γ = 96,28(2)°, Z = 2. The X-ray structure analysis shows the anions to be present as centrosymmetric dimers Se 2 O 2 Cl 6 2- like in the [P(C 6 H 5 ) 4 ] + salt, with two tetragonal SeOCl 4 pyramids linked through a Cl···Cl edge and the lone pairs trans to the axial Se-O bonds (1,589(4) Å). Se-Cl bond lengths are 2.270(1) and 2,351(2) Å (terminal); 2,698(1) and 2,920(1) Å (bridging). The results show that the nature of the reaction products of the Lewis acid SeOCl 2 with halogenides as bases changes very sensitively with small variations in cations and environment. The vibrational spectra are discussed.

Fe 2 (CO) 9 reacts with Cl 2 C(COOEt) 2 to give the paramagnetic complex Fe[ClC(COOEt) 2 ] 3 in high yield. The magnetic and spectroscopic properties of this complex are discussed.

Structure, Tris(trimethylsilyl)aluminium, Sodium-tetrakis(trimethylsilyl)aluminate The crystal and molecular structures of three trimethylsilylaluminium compounds -tris(trimethylsilyl)aluminium coordinated to a diethylether molecule (1), sodium-tetrakis-(trimethylsilyl)aluminate coordinated to two toluene molecules (2b) and unsolvated sodium-tetrakis(trimethylsilyl)aluminate (2a) -have been determined by X-ray structure analysis. In all three compounds the aluminium is tetrahedrally coordinated, the Al-Si-distances lying between 2.44 and 2.49 Å. (1) is monomeric and (2a) and (2b) form linear chains resulting from contact-ion pair interactions.

Chromium(VI) oxide reacts with excess of carboxylic acid anhydrides [(RCO) 2 O where R = CH 3 , C 2 H 5 , n-C 3 H 7 and CHCl 2 ] to give pure chromium(III) carboxylates. Their IR and 1 H NMR spectra suggest the presence of two different types of carboxylate groups. Magnetic susceptibility and absorption spectra favour an octahedral geometry around Cr.

The NMR parameters ( 1 H, 13 C, 31 P, 195 Pt) of compounds of the type cis- and trans- [M(C≡C-R)2(PR′ 3 ) 2 ] (M = Ni, Pd, Pt) are reported. The chemical shifts δ 13 C (M-C≡C; R) and δ 195 Pt (together with UV data) indicate the presence of π-backbonding from the metal into π* C≡C the orbitals. This also explains some unusual features of the coupling constants J(≡ 13 C 1 H), J( 13 C≡ 13 C) and J( 195 Pt 13 C≡). The NMR parameters reflect an increase in the amount of π-backbonding for Pt < Pd < Ni.

N-Methylpyridinium-diiodocuprate(I), C 6 H 8 NCuI 2 and dimethyl(3-dimethylamino-2-aza-2-propenyliden)ammonium-diiodocuprate(I), C 6 H 14 N 3 CuI 2 , are obtained by reacting Cu with C 6 H 8 NI 3 or C 6 H 14 N 3 I 3 in acetone. Both compounds are built up by the organic cations and chains of edge sharing tetrahedra 1 ∞ [Cul 4/2 -]. The iodocuprate(I) anions are in intimate contact with the cations via intermolecular I···C interactions. Though nearly the same average Cu-I distance of 267.2 or 268.2 pm was found for both iodocuprate(I) anions there are different Cu-Cu distances (301-354 pm).

Intensely yellow coloured, insoluble gold(I)-bis(diarylphosphino)amides, [(C 6 H 5 )P 2 NAu, 1, is obtained from lithiated bis(diphenylphosphino)amine and AuCl complexes of tertiary phosphines. 1 is assigned a dimeric eightmembered ring structure on the basis of its 197 Au-Mößbauer spectrum and of a direct analogy with the corresponding bis(phosphino)methanide complexes, whose structure has recently been confirmed by X-ray diffraction. A series of mono- and binuclear AuCl complexes of bis(diarylphosphino)methanes bearing bulky 2-tolyl or 2,6-dimethylphenyl substituents (3a, b) was synthesized from the diphosphines and (CO)AuCl in the molar ratios 1:2 or 1:1. The compounds have structures 4 a, b and oa, b, respectively. An ionic tetrafluoroborate derivative 6 b was obtained from the chloride 5 b on treatment with AgBF 4 . Lithiation of the diphosphinomethanes 3 a, b using LiCH 3 followed by reaction with CIAuPR 3 complexes yields the deep-yellow Au(I) bis(diarylphosphino)methanides 7 a, b. All compounds, including the new ligand 3b and its precursor (2,6-(CH 3 ) 2 C 6 H 3 )2PBr, 2, were characterized by analytical and spectroscopic data.

Dicarbonyl(η 5 -cyclopentadienyl)(η 1 -cyclopropylketenyl)(trimethylphosphane)tungsten reacts with carbon monoxide under reduction of the ketene moiety forming a (σ-bonded acetylene compound. Reaction conditions, spectroscopic data and the X-ray structure of the new compound are reported.

N-Silylated Ureas and Thioureas, Silicon Tetrachloride, Bis(dimethylamino)dimethylsilane N,N′-Diorganylureas react with silicon tetrachloride to give the 1,3,5-triaza-2-silacyclo-hexan-4,6-diones 1-4, in case of N,N′-dicyclohexylurea to give dicyclohexylcarbodiimide. By reacting bis(diethylamino)dimethylsilane with N,N′-diorganylureas and thioureas, resp., one obtains 1,3,5-triaza-2,4-disilacyclohexan-6-ones 6, 10, 13-15, 1-oxa-3,5-diaza-6-silacyclohexan-4-ones 5, 9, 1,3,5-triaza-2-silacyclohexan-4,6-diones 7, 11, 1,3-dioxa-5-aza-2,6-trisilacyclohexanes 8,12, 1,3,5-triaza-2,4-disilacyclohexan-6-thiones 16-25 or the organylamino-diethylamino-dimethylsilanes 26-28. The compounds were characterized analytically and spectroscopically.

The syntheses of two new, potentially hexadentate ligands with an N 3 O 3 donor set is reported: 1,4,7-triazacyclononane-N,N′,N″-tris-2-ethanesulfonate (TES) and 1,4,7-triazacyclononane- N,N′,N″-tris-ethylacetate (TEA). Complexes of the divalent transition metals Co(II), Ni(II), Cu(II) containing these ligands have been prepared. The kinetics of the reactions of [Con(TEA)H 2 O] 2+ and [Co II (TCTA)]-(TCTA= 1,4,7-triazacyclononane- N,N′N″-tris-acetate) with [Fe III (CN) 6 ] 3- , respectively, have been measured. A stable binuclear [Co(TEA)(CN) 6 Fe] - species has been characterized in solution whereas the reaction of [Co(TCTA)]- with [Fe(CN) 6 ] 3- yields [Co III TCTA] and [Fe(CN) 6 ] 4- via an outer-sphere electron transfer reaction (k = 5,9 × 10 3 1 mol -1 sec -1 ; 25 °C, I = 0,26 M). Na[Ni(TES)H 2 O]·5H 2 O crystallizes in the triclinic space group P1̄ (C i 1 -No 2) with cell constants a = 806,7(4), b = 1468,4(8), c = 2317,9(8) pm, α = 72,36(4)°, β = 83,48 (3)°, γ = 81,99(4)°, and Z = 4. The nickel(II) center is in a distorted octahedral environment of a pentadentate TES ligand (N 3 O 2 ) and a coordinated H 2 O. Na[Cu(TES)] 3H 2 O crystallizes in the triclinic space group P1̄ (C i 1 -No 2) with cell constants a = 747,3(3), b - 1082,6(5), c = 1459,3(9) pm, α = 81,13(5)°, β = 84,75(4)°, γ = 79,39(3)°, and Z = 2. The copper(II) center is in a distorted quadratic pyramidal environment of a pentadentate TES ligand. Each of the complex anions contains one uncomplexed CH 2 -CH 2 -SO 3 -group.

CU(C 2 H 6 N 4 O 2 )(C 2 H 5 N 4 O 2 )Cl (1) crystallizes in the monoclinic space group P2 1 /c, a = 8.191(4), b = 10.746(3), c = 13.340(7) Å, β = 104.94(4)°, V = 1134.5 A 3 , Z = 4, d c = 1.96 gem -3 , final Rw = 0.029 for 1785 reflections. In the monomeric complex molecules Cu is coordinated in the shape of a square pyramid with Cl at the apex. In the basal plane only one intramolecular H bridge exists. Cu(C 2 HeN 4 O 2 )Cl 2 (2), crystallizes in the monoclinic space group Pc, a = 7.708(7), b = 3.751(1), c= 13.377(12) Å, β = 105.97(4)°, V = 371.8 Å 3 , Z = 2, dc = 2.25 gcm -3 , final R w - 0.070 for 903 reflections. The stacking of the nearly planar complex units along b leads to a polymeric structure where Cu is additionally coordinated by a Cl atom, and shows a loose interaction with an oxime N atom of an adjacent monomer. The EPR signal intensity shows Curie-Weiss behaviour in the temperature range 110 K-420 K.

1 H NMR Spectra, 31 P NMR Spectra NMR spectra of dialkylthiophosphoryl bromides RR′P(S)Br are analyzed. Methods are demonstrated for C 2 H 5 (i-C 3 H 7 )P(S)Br. A correlation between δ 31ᴘ in the 31 P NMR spectra and the number of β-methyl groups is discussed.

Alkylamino-and cycloalkylaminotriphenylphosphonium halides react with elemental halogens or interhalogen compounds to afford alkylamino-or cycloalkylaminotriphenyl-phosphonium trihalides. The stability of these trihalides depends on the cation as well as the trihalide anion. The assignment of a trihalide structure to these compounds was based on elemental analysis and on IR-and Raman spectroscopic evidence. Most stable are the tribromide and [IX 2 ] ⊖ salts. During all reactions involving N-alkylamino-and N-cyclo-alkylaminotriphenylphosphonium halides and elemental halogens an N-halogenation of the cation was not observed.

Methods are described which allow the synthesis of several plant indole alkaloids and their metabolites at different scales. Compounds synthesized include gramine (1) (3-di-methylaminomethylindole) which is directly derived from indole, while its biosynthetic precursors 3-aminomethylindole (3) and 3-methylaminomethylindole (2) as well as indole-3-carboxylic acid (7) are synthesized via indole-3-aldehyde (6). Slight changes of the experimental conditions allow syntheses with high yields not only at the molar but also at the μmolar level. This is extremely useful when isotope labelled compounds of high specific radioactivity are required for studies of plant metabolism.

Contrary to earlier reports the reaction of sodium trimethylsilanolate with stannous chloride does not yield bis(trimethylsiloxy)tin(II) (1) but a polynuclear compound of the type Sn 2 O(OSiMe 3 ) 2 (2). 1 is obtained from the reaction of stannocene with trimethylsilanole. The compound is a dimer that gives rapid exchange reactions of terminal and bridging trimethylsiloxy groups in inert organic solvents.

β-Phenylethylphosphonium salts in RO-/ROH give styrene in amount depending on the steric requirements of the nucleophile and of the salt. The % of styrene formed increases from 22.9 with leaving group PPH 3 to 85.0 with leaving group P(<-BU)3 in t-BuOK/t-BuOH. Second order rate constants at 30 °C in t-BuOK/t-BuOH are 1.1 · 10 -2 lm -1 s -1 with leaving group P(n-Bu) 3 and 0.96- 10 -2 lm -1 s -1 with leaving group P (cyclohexyl) 3 . The data are consistent with a mechanism of β-elimination.

The C-13 NMR of hecubine and voaphylline are reported. The mass spectrum of hecubine has been studied by high resolution mass measurements, and the fragmentation patterns fol-lowed by a study of metastable ion transitions as determined by linked scan measurements.