Volume 51, Issue 12

The reaction of (dimethylsulfide)gold(I) chloride and bromide with methyl(phenyl)phosphine in ṯetraẖydrof̱uran affords high yields of the colorless, crystalline, chiral complexes [Me(Ph)HP]AuCl/Br ( 1a, b). Treatment of la with potassium iodide in thf leads to a conversion into the corresponding iodide [Me(Ph)HP] Aul ( 1c). The compounds were characterized by their analytical and spectroscopic data, and the crystal structures of la, b have been determined. The two compounds are isomorphous. In the lattice the monomers form chain-like supramolecular aggregates through auriophilic Au-Au contacts. The chains contain both enantiomers following the sequence ..R S R S R S.., with the individual components related by crystal symmetry.

The title complex was obtained by reaction of guanidinium dioxodipicolinatovanadate(V) and N-methyl-N-phenylhydrazine. According to the single crystal structure analysis the dinuclear anion [(μ-PhNNH)(μ-OCH 3 ){(MePhNN(dipic)V)} 2 ] - with sevenfold coordinated metal centers contains two types of hydrazido ligands. The ligand [MePhNN] 2- is terminally bonded, and the VNN unit is linear with extensive electron delocalisation. The V-N and N-N bond lengths are 167.9(5) and 131.9(6) pm, respectively. The bonding of the bridging ligand is of the hitherto unknown μ-μ 2 :μ 2 type, with V-N and N-N bond lengths of 202.5(5) and 136.5(5) pm, respectively. The V(N 2 )V moiety is not planar. The compound was also characterized by 1 H and 51 V NMR spectroscopy.

Bis (3-chloro-4-dodecyloxyphenyl) malondialdehyde copper(II), as well as its nickel(II) homologue have been synthesised. The copper(II) complex shows a narrow (15 °C) nematic phase below its clearing temperature. The nickel(II) complex is polymeric in nature.

Synthetic methods to bifunctional ethynes have been examined. Direct ethynylation, the Stephens-Castro reaction, the Pd-catalysed Hagihara coupling, transmetalation reactions and nucleophilic additions have been evaluated in the preparation of substituted ferrocenylethynes with intended use of these materials in electrochemical and nonlinear optical investigations. Asymmetric ferrocenylethynes are promising candidates for applications in contemporary materials science. Synthetically, 1,4-bis(ferrocenylethynylene)benzene (1), 1,3,5-tris(ferrocenylethynylene) benzene (2), and 9 ,10-bis(ferrocenylethynylene)anthracene (3) are obtained in high yields, whereas 4-ferrocenylethynylene-2,3,5,6-tetrafluorostyrene (4) and potassium (ferrocenylethynylene) triphenyl borate (5) are accessible in only moderate yields. Further extension of this chemistry to additional heteronuclear bimetallic coordination compounds has been attempted, but without success due to severe difficulties in both preparation and characterization of these materials.

The acid strength of alkanepolysulfonic acids was measured using the correlation between the 29 Si NMR shift of the corresponding trimethylsilylester of an acid and the pK S1 -value of the acid. Alkanepolysulfonic trimethylsilylesters XHC(SO 3 -SiMe 3 ) 2 , X 2 C(SO 3 -SiMe 3 ) 2 , XC(SO 3 - SiMe 3 ) 3 and Me 3 Si-O 3 S-(CR 2 ) n -SO 3 -SiMe 3 with X = H, F, Cl, Br, I and R = H, F and n = 1 - 5 were investigated.

Crystals of [Cd(cnge) 2 F 2 ]·3H 2 O (1), Cd(cnge) 2 Br 2 (2) and Hg(cnge)Cl 2 (3) (cnge = cyanoguanidine) were obtained by crystallisation from solutions of CdF 2 , CdBr 2 or HgCl 2 and cyanoguanidine in water/ethanol or methanol. 1 crystallizes monoclinically, space group C2, Z = 2,a = 1629.2(4), b = 1056.6(4), c = 353.9( 1) pm, β = 101.05(2)°; 2 is monoclinic, space group P2 1 /n, Z = 2, a = 391.9(1), b = 850.7(2), c = 1722.1(4) pm, β = 94.06(2)°, 3 is triclinic, space group P1, Z = 1, a = 686.7( 1), b = 693.0(5), c = 387.2(4) pm, α = 94.45(5)°, β = 95.05(4)°, γ = 78.58(5)°. In 1 and 2 each Cd atom is bonded to four halogen atoms to form polymeric (CdF 2 ) n and (CdBr 2 ) n chains, resp., and to two cyanoguanidine molecules. In 3 each Hg atom is bonded to four chlorine atoms also forming (HgCl 2 ) n chains, which are connected via cyanoguanidine molecules acting as a bidentate bridging ligands to form a network.

Borane in tetrahydrofuran (THF-BH 3 /THF; 1) reacts with 1,1,3,3-tetramethyldisilazane (2a) and the cyclic disilazanes (2b), 3 (2c), 4 (2d)] first by formation of amine-borane adducts (3a - d), and then to give /μ-aminodiboranes(6) by H 2 elimination (4a -,d) or cleavage of N-Si bonds (5a-d ), depending on the reaction conditions, in agreement with the results obtained for the reaction of 1 with hexamethyldisilazane. Further transformations proceed via the N,N-disilylaminoboranes 6a - d. In the case of the reaction between 1 and 2b, it proved possible to convert 4b and/or 5b quantitatively into the mixed diaminoborane 7b which served for the synthesis of N,N′,N″-tris[(2′-dimethylsilylethyl)dimethylsilyl]borazine (8b). The Si-H functions in 5b, 7b and 8b react with Co 2 (CO) 8 to afford the respective Si-Co(CO) 4 derivatives 11b - 13b. All compounds were characterized by their 1 H , 11 B, 13 C, 14/15 N and 29 Si NMR spectra.

A series of polynuclear heterometallic complexes containing chromium and zinc or cadmium were prepared by the reaction of cis-[CrCl 2 (en) 2 ]Cl and a zinc or cadmium salt in water and the molecular and crystal structures of 1 to 5 determined by X-ray structure analyses. The products contain chelating or bridging cis-[Cr(OH) 2 (en) 2 ] + groups. For the zinc complexes a tetrahedral coordination is observed, and the [Cr(OH) 2 (en) 2 ] + units are found to act as bridges. [[ZnCl 2 (μ-OH)Cr(en) 2 (μ-OH)]ClO 4 ] n (1) has a chain polymeric structure. [{ZnCl 2 (μ-OH)Cr(en) 2 (μ-OH)} 2 ]Cl 2 (2) has a cyclic structure. In the case of the cadmium complexes the [Cr(OH) 2 (en) 2 ] + units act as chelating ligands. For the three cadmium complexes [Cd 3 (μ-Cl) 4 Cl 4 {Cr(μ3-OH)(μ-OH)(en) 2 } 2 ]·4H20 (3), [[Cd(μ-Cl)(H 2 O) 2 {Cr(μ-OH) 2 (en) 2 }](ClO 4 )(NO 3 )·2H 2 O] n ; (4), and [Cd 2 (μ-Cl)2Cl 3 (H 2 O) 3 { Cr(μ-OH) 2 (en) 2 }] n ; (5) an octahedral coordination sphere is observed. The cadmium atoms in 3 to 5 are connected by at least one chloro bridge. In the centrosymmetrical pentanuclear complex 3 bridging occurs by face-sharing, and in the chain polymeric complexes 4 and 5 by edge-sharing of the coordination octahedra. In the crystal structures of all complexes a network of hydrogen bonds is observed, which contributes substantially to the stability of the conformation of the chain structures.

Preparation and properties of a coordination compound are described, in which a carbonyl group in bis[(dicarbonyl)(μ 5 -cyclopentadienyl)iron] is substituted by hitherto unknown octa- N-methyl-2λ 3 ,4λ 5 -[1,2,4]-oxadiphosphinine-2,4,4,6-tetramine (2). The 1 H , 31 P, and 13 C NMR spectra are recorded and discussed in detail. The molecular structure of the iron complex 4 is described and interpreted.

[(NH 2 ) 3 PNP(NH 2 ) 3 ]Cl has been prepared by a three step synthesis. The last step is the ammonolysis of [Cl 3 PNPCl 3 ]Cl. Single crystals of 1,1,1,3,3,3-hexaamino-1λ 5 , 3λ 5 -diphosphazenium chloride were obtained from an acetonitrile solution in a temperature gradient between 60 °C and room temperature. Between room temperature and -100 °C [(NH 2 ) 3 PNP(NH 2 ) 3 ]Cl is subject to a phase transition. Therefore, the crystal structure was determined by single crystal X-ray methods at room temperature (P1̄, a = 584.7(1) pm, b = 732.1(1) pm, c = 1092.0(2) pm. q = 71.05(3)°, β = 76.36(3)°, γ = 89.83(3)°, Z = 2, R = 4.75 %, wR = 2.47 %). The cation [(NH 2 ) 3 PNP(NH 2 ) 3 ] + is built up by two corner sharing PN 4 tetrahedra. Remarkably short P-N bonding distances have been observed and both PN 4 tetrahedra exhibit a significant distortion resulting in two large and four small N-P-N bond angles.

N-Iodo-triphenylphosphaneimine, Ph 3 PNI, has been prepared by thermolysis of the donor acceptor complex [Me 3 SiNPPh 3· ICl] in boiling acetonitrile in the presence of potassium fluoride. Both compounds have been characterized by IR spectroscopy and by crystal structure determinations. [Me 3 SiNPPh 3 · ICl]: Space group P1̄, Z = 2, a = 888.3(1), b = 1070.7( 1), c = 1310.2( 1) pm, α = 95.15( 1)°, β = 108.67( 1)°, γ = 97.78( 1)° at 20°C. The complex has a molecular structure in which the N atom of the phosphaneimine is connected with the iodine atom of the ICI molecule in a linear arrangement N-I-Cl with bond lengths N-I = 232.7 pm, I-Cl = 255.37 pm. \ Ph 3 PNI: Space group P2 1 /n, Z = 4, a = 952.8(1), b = 1800.8(2), c = 1003.6(1) pm, β = 110.25(1)° at -50°C. The compound forms monomeric molecules with bond lengths PN = 159.1 pm, I-N = 205.6 pm and an INP bond angle of 113.3°.

The generation of silaethenes Me 2 Si=CH(SiMe 3 ) (1), Me 2 Si=CH(SitBu 3 ) (2), tBuMeSi=CH(SitBu 3 ) (3), and tBu 2 Si=CH 2 (4) from metal organyls >SiX-CM< (X = Br, F; M = Na, Li) by elimination of MX is investigated. The metal organyls are prepared from >SiX-CBr< and RM (R = tBu 3 Si, nBu, Ph) by Br/M exchange (for preparation of >SiX-CBr< cf. Scheme 1). Only the sterically overcrowded silaethenes 2 and 3. generated from Me 2 SiF-CHNa(SitBu 3 ) and tBuMeSiF-CHNa(SitBu 3 ), have been identified by trapping with isobutene and dimethylbutadiene under formation of ene and Diels-Alder adducts. Analogous products are not found from Me 2 SiBr-CHNa(SiMe 3 ) and tBu 2 -SiBr-CH 2 -Li. In the absence of trapping agents, compounds 1, 2, and 3 form cyclodimers. A reaction intermediate of the formation of 1 × 1 has been isolated and the structures of 2 × 2 and 3 × 3 have been solved by X-ray analysis. No dimer is observed for 4. In this case compounds are formed which may be interpreted as insertion products of 4 into the CLi bond of the precursor.

The bis(triphenylphosphonio)propenide cation 1 provides two reactive CH sites in 1,3- position and can be condensed with the bis(dichlorophosphanyl)methylene triphenylphosphorane 2 or the bis(dichlorophosphanyl)aniline 3 to form cationic six-membered rings: A tetrahydro-1,3-diphosphinine (4) with three phosphonio or phosphoranediyl substituents in 2,4,6-position and a tetrahydro-1,2,6-azadiphosphinine (5) carrying two such substituents in 3,5-position. The bromide of the latter was used for an X-ray structure analysis. The P III ring members of the cations 4 and 5 can be oxidized in two steps by elemental sulfur to give the monothioxo and dithioxo derivatives 6. 7 and 8, 9. respectively. A crystal of the mixed chloride/bromide of 8 was used for another X-ray structure analysis.

Two new epimers of ajmaline (1) and isoajmaline (2) were synthesized by means of tosylation followed by hydrolysis with NaOH/CH 3 OH. Displacement of tosyl with hydroxyl group yielded C 21 epimers of these alkaloids. The structures were identified by various spectroscopic techniques.

The crystal and molecular structure of aminoguanidine monohydrochloride, CN 4 H 7 + .CL - in which aminonoguanidine exists in the monocation form, was determined by single-crystal X-ray diffraction. The structure of the monocation is largely similar to that of aminoguanidine dication as present in previously studied divalent salts. The monocation was found to exist in the form of the tautom er that allows strong resonance in the guanyl group. As compared to the dication, the terminal hydrazine nitrogen atom bears one hydrogen atom less. The monocation is planar, the only atoms deviating from the plane being the hydrogens attached to the terminal hydrazine nitrogen. Quantum chemical calculations on the endiamine tautomer of aminoguanidine free base as well as on aminoguanidine monocation and dication were also perform ed by using the HF and MP2 ab initio methods and also the B3- LYP and B-LYP methods based on density functional theory. On the basis of the calculations, a predicted structure of the endiamine tautom er of aminoguanidine free base is presented

Harmine ( 1) upon refluxing with selenium dioxide in acetic acid for 15 hours yielded bisharmine selenide (4) via the intermediates 2 and 3.

A regioselective synthesis of 3-iodo-3-deoxy sugars is described by trans-diaxial cleavage of the oxirane ring of 2.3-anhydropyranosides with halogenated titanium isopropoxide reagents and samarium iodide.

3-Hydroximino-isoindolines and 3-hydroxylamino-1 H-isoindoles with substituents at the five membered ring have been prepared by condensation of substituted 3-alkoxy-1 H-isoindoles with hydroxylamine and O-/N -substituted hydroxylamines. Constitution and configuration of semi-cyclic amidoximes were derived from spectroscopic investigations and deduced on the basis of orientating chemical transformations. These results have been established by a crystal structure determination of a representative 3-hydroximino-isoindoline.

The molecular structure of tri(2-thienyl)borane (1) was determined [monoclinic, space group P2 1 / c; a = 12.216(2), b = 7.765(2), c = 12.605(2) Å, β = 93.13(2)°]; two of the three thienyl groups are disordered, as is also indicated by the solid-state 13 C CP/MAS NMR spectrum of 1. The 13 C NMR spectra of 1 were measured at variable tem perature in solution and the barrier to rotation about the B-C bonds was found to be <35 kJ/mol. Thus, CB(pp)π interactions must be regarded as rather weak, in spite of suggestive δ 11 B. δ 13 C data and structural parameters.

Hydrazone dehydrogenation with silver(I) oxide in the presence of sodium hydroxide was found an efficient approach to the title compounds, whereas application of the Bamford-Stevens reaction proved unsatisfactory.