Volume 47, Issue 6

The 1 H NMR spectrum of the spirophosphorane 3 at room temperature indicates dynamic behaviour of the cation. The low-temperature 1 H NMR spectra of 3 exhibit two sets of doublets for the protons of the diastereotopic N(CH 3 ) 2 groups. The free enthalpy of activation for the dynamic process was determined (58.6 KJ/mole). In the reaction of 3 with sodium tetraphenylborate the crystalline compound, 4, involving the non-coordinating anion, [B(C 6 H 5 ) 4 ]-, was obtained. The X-ray crystal structure analysis of 4 reveals the presence of a five-membered ring, formally as a result of intramolecular donor-acceptor interaction between the nitrogen atom of the N(CH 3 ) 2 group and phosphorus. The geometry at phosphorus deviates somewhat from ideal trigonal bipyramidal.

In the reaction of phenylisocyanate, 1, with 1,3-dimethylurea, 2, and 1,3-diphenylurea, 4, 1,3-dimethyl-5-phenyl biuret, 3, and 1,3,5-triphenylbiuret, 5, respectively, were obtained. The reaction of 3, 5 and of 1,3,5-trimethylbiuret 6 with a range of P(III) chloro compounds has furnished the new 4,6-dioxo-1,3,5,2 λ 3 -triazaphosphinanes, 7-16. The characterization of 7-16 rests, especially, on their 1 H, 13 C and 31 P NMR, and mass spectra.

A very easy and safe way for the production of Ni-doped magnesium hydride is reported. Another process, which is not requiring transition metals (e. g. nickel) has also been found as a means to ameliorate the kinetics of hydrogen uptake. MgH 2 itself exerts a catalytic effect on the formation of magnesium hydride from the elements, i. e. by autocatalysis.

Trifluoromethylation of C1 2 BN(CH 2 ) 6 , Cl 2 B(tmp), tmp = 2,2,6,6-tetramethylpiperidino, and Cl 2 BN(t-Bu)(Bz) with three equivalents of CF 3 Br/P(NEt2) 3 yields the amine complexes (CF 3 ) 3 B · NH(CH 2 ) 6 (1), (CF 3 ) 3 B ·NH 2 CMe 2 (CH 2 ) 2 CHCMe 2 (2) and (CF 3 ) 3 B · NH 2 (Bz) (3). The preparation of 3 was accompanied by formation of three unexpected trifluoromethylboron derivatives X(CF 3 ) 2 BCH(Ph)NH(t-Bu)(Bz) (D), X = Br (4), Cl (5), and (Ph)(CF 3 ) 2 BCHN(t-Bu)(Bz) (6), the latter being formed from 4 by HBr elimination and rearrangement. Reaction of 4 with H 2 O, EtOH, HCONMe 2 and Me 3 SnH yielded D, X = OH (7), EtO (8), HCOO (9), and (Ph)(CF 3 ) 2 BCH 2 NH(t-Bu)(Bz) (10), respectively. The structures of 1, 6 and 7 have been determined by X-ray diffraction analysis.

The crystal structures of AMnF 4 compounds (A = K, Rb, Cs) were determined by X-ray diffraction on twinned single crystals: The K and Rb compound are isostructural: space group P21/a, Z = 4; KMnF 4 : lattice constants a = 769.9(2), b = 764.4(2), c = 576.9(1) pm, β = 90.54(3)°; R/wR = 0.029/0.025 for 481 reflections; pseudomerohedral (100) twin. RbMnF 4 : lattice constants a = 782.2(5), b = 777.7(3), c = 605.0(2) pm, β = 90.83(4)°; R/wR = 0.0665/0.0513 for 471 reflections. The structure of CsMnF 4 has been refined anew in the space group P4/n (Z = 4) as a merohedral (110) twin (lattice constants a = 794.40(6), c = 633.76(9) pm; R/wR = 0.051/0.044 for 820 reflections). All three structures derive from the T1A1F 4 type and show puckered [MnF 4 ] - layers with an antiferrodistortive order of strongly Jahn-Teller distorted [MnF 6 ] octahedra. The elongated axes (Mn-F for KMnF 4 : 215.8, RbMnF 4 215.2, CsMnF 4 216.8 pm) alternate with shorter ones (188.1,188.3,185.4 pm) within the layer planes. The terminal Mn-F bonds are very short (180.3, 180.6,181.7 pm). The Mn-F-Mn bridging angles are 140.6° and 146.4° for the K, 148.3° and 152.1° for the Rb, and 161.9° for the Cs compound. The magnetostructural relations and the three puckering types are discussed for all the AMnF 4 layered structures.

Single crystals of enH 2 MnF 5 (en = ethylenediamine) have been prepared from aqueous HF solution and the crystal structure was determined by X-ray diffraction: space group Cccm, Z = 16, a = 1710.5(4), b = 1799.2(4), c = 847.8(2) pm, R/wR = 0.040/0.028 for 977 reflections. The structure consists of kinked [MnF 5]2- - chains built by MnF 6 octahedra sharing trans vertices (angles Mn-F-Mn 161.2 and 157.8°). The bridging Mn-F ax bonds are strongly elongated by the Jahn-Teller effect (mean Mn-F ax 215.4, Mn-F 183.8 pm). Each of the enH 2 2+ cations is connected to four anionic chains by hydrogen bonds forming a 3 D network. Thermal decomposition occurs between 200 and 380 °C in two steps giving finally MnF 2 . The IR spectra of enH 2 MnF 5 and its decomposition products are reported.

The silene 2 is formed by reacting 2-chloro-1,3-bis(trimethylsilyl)-2-vinyl-1,3-diaza-2-silacyclopentane (5) with LiBu t in n-pentane in the temperature range from -10 to +10°C. The reaction primarily leads to the corresponding a-lithio adduct 6 by addition of the Li-organyl to the vinyl group of 5; subsequent 1,2-LiCl elimination yields 2 as an intermediate. 2 can be trapped by polar reagents Me 3 SiX (X = OMe, OSO 2 CF 3 ) as well as by organic dienes which add across the Si=C bond; in the absence of trapping agents, trisilacyclohexane 7 is isolated. The cycloaddition behaviour of 2 is best described by the two mesomeric formulae (a) and (β), with competitive [4+2] and [2+2] addition routes: While with butadienes and norborna-2,5-diene the [2+2] products are formed mainly in a multiple step reaction via zwitterionic intermediates (1,4 dipoles), the ratio of the [4+2]/[2+2] derivatives from 2 and cyclohexa-1,3-diene becomes nearly equivalent. 2 is thus quite comparable in its reactivity to dichloroneopentylsilene, Cl 2 Si = CHCH 2 Bu t .

The reaction of 2-chloro-1,3-bis(trimethylsilyl)-2-(1′-trimethylsilyl-ethenyl)-1,3-diaza-2-silacyclopentane (5) and LiBu leads to the α-lithio adduct 8 which can be trapped by Me 3 Sitriflate to give 13b, and is a useful silene precursor. Subsequent 1,2-LiCl elimination yields 2 as an intermediate, which does not cyclodimerise giving a 1,3-disilacyclobutane, but can be trapped by Me 3 SiOMe and suitable dienes which add across the Si=C bond. In contrast to silene 1, which favours the [2+2] addition, 2 exclusively forms the Diels-Alder isomers with 2-methyl-1,3-butadiene and 2,3-dimethyl-1,3-butadiene (6 and 7), and the ene products 11 and 12 with norborna-2,5-diene and cyclohexa-1,3-diene, respectively. This quite different cycloaddition behaviour results from the substitution pattern at the Si=C framework, with a changing polarity. 2 thus appears to be a rather electron deficient silene having a polarity more comparable to that of diorganosilenes rather than to 1, which may be compared in its reactivity with Cl 2 Si = CHCH 2 Bu.

Reaction of VC1 4 with (Me 3 Si) 2 S in CH 2 C1 2 yields an insoluble product with the approximate composition VSC1 2 . Its reaction with PPh 4 Cl in CH 2 Cl 2 affords (PPh 4 ) 3 [V 2 Cl 9 ] · 7 CH 2 Cl 2 , whereas PPh 4 [VOCl 4 ] is formed in the presence of oxygen. According to an X-ray crystal structure analysis, (PPh 4 ) 3 [V 2 Cl 9 ] · 7 CH 2 Cl 2 contains [V 2 C1 9 ] 3- ions having two face-sharing coordination octahedra but no significant metal-metal bonding (V-V distance 327.5 pm). Crystal data: a = 1386.4(7), b = 1405.6(7), c = 2710(2) pm, α = 95.800(5), β = 95.370(5), γ = 118.11(3)°, triclinic, Ρ 1̄, Ζ = 2; R = 0.066 for 8779 observed reflexions. PPh 4 [VOCl 4 ] is isotypic with AsPh 4 [VOCl 4 ] and contains tetragonal-pyramidal [VOCl 4 ] - ions; tetragonal, P4/n, Z = 2, a = 1264.5(2), c = 772.0(2) pm; R = 0.050 for 654 observed reflexions.

NaNEt 4 S 4 was obtained from an equimolar solution of Na 2 S 4 and NEt 4 Cl in ethanol. Its crystal structure was determined by X-ray diffraction with 4175 observed unique reflexions, R = 0.044. Crystal data: a = 713.4(4), b = 1744.5(9), c = 1204.0(5) pm, β = 105.8(3)°, space group P2 1 /n, Ζ = 4. In the structure, chains consisting of Na + and S 4 2− ions run in the a direction, every Na + being coordinated by four terminal S atoms of S 4 2− ions (two terminal, one chelating). The chains are separated by the NEt 4 + ions.

(o-Bromobenzyl)diphenylphosphine, 1, and 1,3-Bis(diphenylphosphinomethyl)benzene, 2, have conformations in the solid state with the phosphino groups being displaced noticeably from the plane of the central aromatic rings. The molecular structures allow conclusions about the chelating complexation capability of the ligands (o-diphenylphosphinomethyl)phenyl(-1) and 2,6-bis(diphenylphosphinomethyl)phenyl(-1) derived from 1 and 2 by metallation.

The isolation of 3,6,9,12-tetraazatetradecane-1,14-diamine (linear isomer of pentaethylenehexamine, linpen) from a technical polyamine mixture is described. In methanol, linpen acts as a hexadentate ligand towards cadmium(II). The solid compounds [Cd(linpen)](BPh 4 ) 2 (1), [Cd(linpen)](BPh 4 ) 2 •2 DMSO (2) and [Cd(linpen)](BF 4 ) 2 (3) have been isolated and characterized by elemental analysis, spectroscopy and X-ray powder diffraction. The 113 Cd NMR resonance of 1 is at 351 ppm (0.30 M in DMSO-d 6 , standard: 0.10 M Cd(ClO 4 ) 2 in D 2 O). 2 and 3 have been structurally characterized by single-crystal X-ray diffraction. 2: C 2/c; a = 19.337(1)Å, b = 17.937(1)Å, c = 18.584(1)Å, β = 111.54(1)°; Z = 4, R = 0.034, R w = 0.033.3: P2 1 /n; a = 8.607(1)Å, b = 14.851(2)Å, c = 15.703(2)Å, ß = 91.21(2)°; Z = 4,R = 0.083, R w = 0.072. Both compounds contain discrete [Cd(linpen)] 2+ complexes. The hexamine wraps around the metal ion in a helical manner. This results in a strong distortion of the coordination polyhedron. The mean Cd-N bond lengths are 2.38Å and 2.37Å for 2 and 3, respectively. Models for MN 6 centers in metal-polyethyleneimine (PEI) complexes are derived from the structure of [Cd(linpen)] 2+ . For example, loops at the MN 6 site in molecules of linear PEI are proposed.

The crystal structure of the title compound was determined in order to obtain structural information on a tetrapyrrole bearing meso-oxo-functions. C 36 H 42 N 4 O2T1C1 · CH 3 OH, P1̄, a = 10.358(2), b = 12.344(3), c = 15.490(3) Å, a = 84.36(2)°, β = 78.53(2)°, γ = 82.26(2)°, V = 1918.2(7) Å 3 , Z = 2, 130 K, R = 0.04 for 6749 reflections with I > 4σ(Ι). The structure consists of the penta-coordinated thallium ligated by the four nitrogens of the porphodimethene ligand and a chloride in the axial position. The central macrocycle shows some degree of ruffling with the carbonyl groups pointing slightly above and below the mean plane of the molecule.

The isolation and spectroscopic characterization of (-)-allo-proto-lichesterinic acid from Cetraria komarovii is described. Proto-lichesterinic and allo-proto-lichesterinic acids are transformed into numerous nitrogen-containing derivatives and the isomerization of the dihydro acids is investigated.

Bis(silylamino)difluorosilanes (1,2) are prepared in the reaction of lithiated di-tert-butylmethyl- and tert-butyl-dimethylsilylamine with tetrafluorosilane. The dilithium derivative of 1 reacts with SiF 4 to give the tetrafluoro-substituted four-membered (Si-N) ring system [(CMe 3 ) 2 MeSiN-SiF2] 2 (3). Two four-membered rings [(RN-SiF 2 ) 2 (4), (RN-SiFNRSiF 3 ) 2 (5), R=CMe 3 SiMe2] are obtained in the reaction of dilithiated 2 with SiF 4 . The dilithiated silylamines and SiF 4 also react with formation of 3 and 4. However, besides 4 the six-membered ring (CMe 3 SiMe 2 N-SiF 2 ) 3 (6) is obtained. Crystal structures of 3,5, and 6 were determined. A transannular Si ··· Si ring distance of 237,5 pm is found in 3.

Acetylation reaction’s product(s) of 3-[L-threo-2,3,4-trihydroxy-1-(2-naphthylhydrazono)-butyl]quinoxalin-2(1H)-one (2b) were found to be dependent on the reaction condition. While the tri-O-acetyl (3b) was isolated in high yield from 2b under the action of acetic anhydride/pyridine mixture, compounds 4b and 5b as well as trace of 3b were obtained when 2b was heated in acetic anhydride. On the other hand, 3-[1-(2-naphthylhydrazono)-glyoxal-1-yl]quinoxalin-2(1H)-one (7) underwent ring closure and afforded the condensed tricyclic compound 8 under the action of acetic anhydride/pyridine mixture.

That lithiated aromatic amines with more than one nitrogen atom can favor polymeric aggregates in the solid state is demonstrated by the single crystal X-ray diffraction structure of [N-lithio-benzimidazole(DMSO) 2 ] ∞ 4; ab initio calculations on model compounds and simple electrostatic models indicate that the preference of the polymeric structure over dimeric alternatives is due to resonance stabilization and to Coulomb attraction between alternating benzimidazole anions and lithium cations.

β-Cyclodextrin was derivatized with 1-bromoalkanes of different chain lengths. The yield as well as the purity of the resulting cyclodextrin derivatives were improved by using solvent mixtures instead of pure solvents. The heptakis(2,6-di-O-alkyl)- and heptakis(2,3,6-tri-O-alkyl)-β-cyclodextrins were studied by means of NMR spectroscopy employing one-dimensional as well as two-dimensional NMR techniques. Analysis of the NMR data showed that only in completely derivatized β-cyclodextrins the cyclodextrin torus undergoes a conformational change. Best separation factors were found for the cyclodextrin derivative with the highest internal mobility as determined from the corresponding NT 1 -values, the validity of which was confirmed by NOE determinations. Therefore, 13 C relaxation times could be used as a measure of the efficiency and usefulness of a given cyclodextrin derivative as an enantioselective stationary phase.

The preparation of four 2-(4-toluenesulphonyl)-3-aryloxaziridines by oxidation of the corresponding imines by peracids is described. The relative oxidation rates of trimethyl phosphite by these oxaziridines are determined.

A short synthesis of 17α-pregna-2,4-dien-[2,3-d]isoxazol-17β-ol (1) is described using mild reaction conditions and with a high overall yield. The equilibrium between keto-enolic forms has been studied by 1 H NMR methods. Complete assignments of all the resonances in the 1 H and 13 C NMR spectra of Danazol have been made using a variety of one and two-dimensional correlation methods. 13 C NMR spectra of all the intermediate and related model compounds were also assigned.

Starting from 3-chloro-2-oxo-1,4-dithiane the title compound was prepared and characterized analytically and spectroscopically. It was used then for the preparation of some new tetrachalcogenafulvalenes (π-donor molecules).

The mixed valence compound Ga 0,5 V 2 Se 4 has been prepared and characterized by X-ray powder methods and infrared spectroscopy. The compound crystallizes in a spinel structure with 1:1 ordering on the tetrahedral sites. The lattice parameter of the cubic cell is a = 1013.8 pm.

The functional mono- and di(t-butyl)boron compounds t BuB(OMe) 2 and t Bu 2 Bu 2 BOMe are easily prepared in good yield by a one-pot synthesis from excess B(OMe) 3 and t-butyllithium in ether at -60 °C.