Volume 57, Issue 6

The title compounds have been synthesized via oxidation of the elemental pnicogenes (M = As, Bi) with the hyperoxides AO 2 (A = K, Rb, Cs) and their crystal structures were determined on the basis of single crystal X-ray data. In K 3 AsO 4 (orthorhombic, Cccm, a = 1060:1(1), b = 1135:2(1), c = 1694:0(2) pm, Z = 16) and Cs 3 AsO 4 (orthorhombic, Pnma, a = 1254:3(2), b = 902:9(2), c = 658:5(3) pm, Z = 4) isolated tetrahedra [AsO 4 ] 3- with distances As-O between 167.0 and 170.5 pm are present, which are arranged in a nearly cubic close packing. The structure of K 3 BiO 4 (triclinic, P1̄, a = 643:18(6), b = 657:27(6), c = 762:41(7) pm, α = 101:724(2)°, β = 96:472(2)°, γ = 105:465(2)°, Z = 2) contains centrosymmetric dimers [O 3 BiO 2 BiO 3 ] 6- , in which the Bi(V) atoms are surrounded by five O atoms in a distorted trigonal bipyramidal geometry with distances Bi-O in the range of 199.5 to 233.1 pm.

Keywords (Triphenylphosphine)gold(I) pivalate (1), and (triphenylphosphine)gold(I), [tri(p-tolyl)-phosphine]gold(I), [(4-dimethylaminophenyl)diphenylphosphine]gold(I), and (cyclohexylisocyanide) gold(I) pentafluoropropionate (2 -5) have been prepared from the corresponding gold(I) halide complexes and silver carboxylates in high yields. The products are stable to air and moisture and soluble in most common polar organic solvents. The structures of 1 and 3 have been determined. Owing to the bulk of the carboxylate substituents the molecules are monomers in the crystal. Compounds 1 - 4 undergo thermal decomposition in a narrow temperature range around 130°C, 5 is less stable and decomposes at 48° C.

Tetrabutylammonium carbonyltribromoplatinate(II) [(C 4 H 9 ) 4 N][PtBr 3 (CO)] crystallises in the monoclinic system in the space group P2 1 /n with a = 1487.84(13), b = 897.41(8), c = 1849.6(2) pm, β = 106.558(2)° and four formula units per unit cell. The [PtBr 3 (CO)] - anion is symmetrical (C 2v ) and almost planar with Pt-Br bond lengths of 242.40(12) pm (trans to CO), 243.25(10) pm and 242.99(9) pm (trans to Br), and a Pt-C bond length of 185.6(11) pm.

In the superacidic system HF/SbF 5 , the salt [Hg 2 (CO) 2 ][Sb 2 F 11 ] 2 reacts with traces of water to give the novel salt bis(aqua)dimercury(I) bis(hexafluoroantimonate)tetra(hydrogenfluoride) solvate [Hg 2 (OH 2 ) 2 ][SbF 6 ] 2 · 4HF. It crystallises in the triclinic system in the space group P1̄ with a = 661.47(6), b = 695.11(7), c = 922.29(9) pm, α = 83.428(5)°, β = 84.186(6)°, γ = 71.696(5)°, and one formula unit per unit cell. The four heavy atoms of the [Hg 2 (OH 2 ) 2 ] 2 + cation are linked symmetrically and almost linear (nearly C 2h ) with a Hg-Hg bond length of 249.17(11) pm, two terminal Hg-O bonds of 214.8(8) pm, and an O-Hg-Hg bond angle of 177.6(3)°. Final R indices [I > 2σ(I)] are R 1 = 0.0405 and wR 2 = 0.0714.

Tetraphenylphosphonium tetraazidoborate, [P(C 6 H 5 ) 4 ][B(N 3 ) 4 ], was obtained from B(N 3 ) 3 - in situ prepared from BH 3 · O(C 2 H 5 ) 2 and HN 3 - and [P(C 6 H 5 ) 4 ][N 3 ]. Recrystallization from an acetonitrile / hexane mixture yielded colorless crystals in 60% yield. The molecular structurewas determined by single crystal X-ray diffraction and the [B(N 3 ) 4 ] - anionwas shown to possess S 4 symmetry.

Two isostructural hydroxo bridged dinuclear lanthanide phen complexes of general composition [Ln 2 (phen) 4 (H 2 O) 4 (OH) 2 ](phen) 2 (NO 3 ) 4 with Ln = Tm (1), Yb (2) were prepared by reactions of the corresponding lanthanide nitrate and phenanthroline monohydrate in CH 3 OH/H 2 O at pH = 5.5. They crystallize in the triclinic space group P1̄ (no. 2) with the cell dimensions: a = 11.233(1), b = 11.456(1), c = 14.011(2) Å , α = 93.91(1)°, β = 98.20(1)°, γ = 108.21(1)°, V = 1683.0(3)Å 3 , Z = 1 for 1 and a = 11.236(1), b = 11.480(2), c = 13.986(2)Å , α = 93.91(1)°, β = 98.17(1)°, γ = 108.33(1)°, V = 1682.9(3) Å 3 , Z = 1 for 2. The crystal structures are composed of the hydroxo bridged dinuclear [Ln 2 (phen) 4 (H 2 O) 4 (OH) 4 ] 4+ complex cations, hydrogen bonded NO 3 - anions and π-π stacking (phen) 2 dimers. The lanthanide atoms are each surrounded by two phen ligands, two H 2 O molecules and two μ-OH groups to complete a tetragonal antiprismatic LnN 4 O 4 coordination. Via two common μ-OH groups, two neighboring tetragonal antiprisms are condensed to form a centrosymmetric dinuclear [Ln 2 (phen) 4 (H 2 O) 4 (OH) 4 ] 4+ complex cation. The complex cations and (phen) 2 dimers are assembled via π-π stacking interactions and hydrogen bondings into 2D layers parallel to (101̄), between which the hydrogen bonded NO 3 - anions are sandwiched. The Tm compound shows paramagnetic behavior with an experimental magnetic moment of 7.51 μ B at room temperature. No magnetic ordering is evident down to 5 K. Over the temperature range 70 - 300 K, the Yb compound obeys the Curie-Weiss law with an experimental magnetic moment of 4.32 μ B at room temperature and shows weak ferrimagnetic behavior at low temperature.

The reaction of 2,3-dihydro-1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (7, Im) and alkyl iodides has been investigated. With MeI, 7 forms a 1/1 mixture of [ImH]I (10) and [ImEt]I (11a) while from the reaction of 7 with EtI an 1/1/1 mixture of 10, 11a and [ImCH(Me)Et]I (11b) is obtained. The mechanism of the reactions is discussed, and the crystal structures of 10 and 11a are reported.

The hetero-Diels-Alder reaction of 1-(2-furyl)-3-(dimethylamino)-2-propene-1-thione (diene) with maleic and fumaric acids, and β-nitrostyrenes yielded 3,4-dihydro-2H-thiopyran derivatives. Treatment of some of those cycloadducts with acetic acid caused elimination of dimethylamine yielding stable 2H-thiopyrans. Reaction of the diene with maleic anhydride furnished a cycloadduct which underwent spontaneous rearrangement to form an N,N-dimethylamide derivative. Cycloadditions of the diene to maleimide, N-phenylmaleimide, diethyl maleate, fumarate and butenolide, carried out in the presence of acetic anhydride,were followed by elimination of dimethylamine, afforded stable 2H-thiopyran derivatives.

The preparation, crystal structure and optical absorption spectra of [CH 3 SC(NH 2 ) 2 ] 3 SnI 5 (1), [CH 3 SC(NH 2 ) 2 ][HSC(NH 2 ) 2 ]SnBr 4 (2), (CH 3 C 5 H 4 NCH 3 )PbBr 3 (3), and [C 6 H 5 CH 2 SC-(NH 2 ) 2 ] 4 Pb 3 I 10 (4) are reported. The compounds 1, 2, 3 consist of MX 6 -octahedra (M = Sn, Pb, X = I, Br) forming one-dimensional single chains (compounds 1, 3) or double chains (compound 2). The compound 4 forms a two-dimensional inorganic network via corner sharing of three face sharing octahedral units. Because of their low-dimensional character, a blue shift of the excitonic absorption bands, in comparison to those of higher dimensionality systems, is observed.

N-(5-Chlorosalicylidene)-2-hydroxy-5-chloroaniline was synthesized and its crystal structure determined. It crystallizes in the orthorhombic space group Pna2 1 with a = 14.668(4), b = 6.084(3), c = 27.980(4) Å , R = 0.051 for 4788 independent reflections). There are two independent nearly planar molecules in the asymmetric unit. The intramolecular hydrogen bonds occur between the pairs of atoms N1 and O1 [2.553(6) Å], N1 and O2 [2.585(5) Å], N2 and O3 [2.567(6) Å], N2 and O4 [2.620(5) Å], the hydrogen atoms essentially being bonded to the nitrogen atoms. The neighboring molecules are linked via an intermolecular O-H···O hydrogen bond [2.557(5) Å ]. Conformations of the title compound were investigated by semi-empirical quantum mechanical AM1 calculations. The optimized geometry of the molecular structure corresponding to the nearly planar conformation is the most stable conformation in the calculations. The results strongly indicate that the minimum energy conformation is primarily determined by non-bonded steric interactions.

The crystal structures of [M(nic) 2 (H2O) 4 ](sac) 2 (nic = nocotinamide; sac = saccharinate anion) with M = Co(II), Ni(II) and Zn(II), have been determined at 116 K by single-crystal X-ray diffractometry. The compounds crystallize in the triclinic space group P1̅ with Z = 1, and the M(II) cations present a slightly distorted MN 2 O 4 octahedral environment, with equatorially coordinated water molecules and axially pyridine N-bound nicotinamide ligands. The saccharinate anions act as counteranions, and are not part of the first coordination sphere. Some comparisons with related structures have been made and the most important features of their IR spectra discussed.

The solution enthalpies have been determined for the ternary phases RE 2 Se x O 3+2x existing on the pseudo-binary section RE 2 O 3 -SeO 2 and for RE 2 O 3 and SeO 2 in 4n HCl (RE =Nd, Sm, Y). From these date the enthalpies of formation of the ternary phases have been derived via suitable solution schemes on the basis of the known enthalpies of formation of RE 2 O 3 and SeO 2 .

α-Benzylamino-β-(5,5-dioxodibenzothiophen-2-carbonyl)propionic acid (1) has been synthesized by treating the corresponding β-aroylacrylic acid with benzylamine in dry benzene. On treatment with hydrazine hydrate the keto acid 1 furnishes the corresponding pyridazinone derivative 2. The behaviour of 2 towards carbon electrophiles, namely, ethyl chloroacetate, acrylonitrile, formaldehyde and secondary amines (under Mannich reaction conditions), aromatic aldehydes and carbon nucleophiles, namely, POCl 3 /PCl 3 and P 2 S 5 has been investigated. The 3-chloropyridazine derivative 13 reacts with hydrazine hydrate to give the 3-hydrazino derivative 14. On treatment with ethyl acetoacetate and/or acetylacetone the hydrazine 14 undergoes cyclization to afford pyrazolone derivative 16 and 3-(3,5-dimethylpyrazol- 1-yl)pyridazine derivative 17, respectively. On reaction with acetylhydrazine in boiling butanol and/or sodium azide in DMF the 3-chloropyridazine derivative 13 affords the triazolo[4,3-b]pyridazine 18 and the tetrazolo[1,5-b]pyridazine 19, respectively. The anti-microbial activity of the synthesized derivatives has been investigated.

The synthesis of several new nitronyl nitroxides with mesogenic groups is reported (6a, b, 11, 14a, b). Microscopic investigations revealed that in some cases (6b, 14b) highly ordered mesogenic phases are formed.

The new Schiff base ligand N-(2-fluoro-3-methoxy)-salicylaldimine (C 14 H 12 NO 2 F) (1) has been synthesised and studied by using, IR, 1 H NMR, 13 C NMR, UV-visible, GC-MS techniques, X-ray structure analysis and AM1 semi-empirical quantum mechanical methods. Compound 1 crystallises in the orthorhombic space group P2 1 2 1 2 1 with a =12.5461(1), b =18.0495(1), c =5.2615(1) Å . An intramolecular hydrogen bond connects O1 and N1 [2.575(2)Å], the hydrogen atom being bonded essentially to the oxygen atom. Minimum energy conformations were calculated as a function of two torsion angles θ 1 (C6-C7-C8-N1) and θ 2 (C7-C8-N1-C9), varied every 10 degrees. The optimized geometry of the crystal structure corresponding to the non-planar conformation is the most stable conformation in all calculations. The results strongly indicate that the minimum energy conformation is primarily determined by hydrogen-hydrogen repulsions between the ortho-hydrogen atoms on the aldehyde rings. Complementary IR, 1 H NMR and UV measurements in solution and in the solid state were carried out.

The regioselective addition of deprotonated alkynes (phenyl-1-propyne, propargyl ether or tetrahydropyran-protected 3-butyn-1-ol) to the imine group was identified as a competitive process to the nucleophilic addition to the keto group of (1S)-3-oxo-camphorsulfonylimine. The selectivity of the process depends on the characteristics of the nucleophile and the reaction conditions. In the case of propargyl ether it was possible to render the imine addition the main process. The structural characterization of compounds 1, 2, 6 by X-ray diffraction analysis show that the C2 - C3 bond becomes longer upon nucleophilic addition to the imine group of (1S)-3-oxo-camphorsulfonylimine. This trend is believed to favour the ring opening process that undergoes the formation of the spiro type compound 7.

1,4,7,8,9,10-Hexahydro-6H-[1]benzothieno[2’,3’:4,5]pyrimido[1,2-b][1,2,4,5]tetrazin-6-ones were prepared via reaction of 2,3,5,6,7,8-hexahydro-3-amino-2-thioxo[1]benzothieno[2,3-d]- pyrimidin-4(1H)-one or its 2-methylthio derivative with hydrazonoyl halides in ethanol in the presence of triethylamine. Some of the products were screened for their biological activity.

Starting from 2,3-dichloro-1,4-dioxane, the title compound was prepared by a five-step chemical procedure, instead of a eight-step procedure reported recently.

Pt(naph-en)Cl 2 with naph-en =N-(1-naphthyl)- ethylenediamine was synthesized and spectroscopically characterized. The complex shows a fluorescence at λ max = 405 nm, which originates from the appended naphthyl substituent present as an electronically isolated chromophore.