Volume 60, Issue 5

Mixed sodium thio/oxo orthovanadates(V), dark red Na 3 [VS 3 O] and orange red Na 3 [VS 2 O 2 ], were synthesized via reactions in the melt starting from V, Na, Na 2 S, Na 2 O and sulfur. The structure of the low temperature phase of Na 3 [VS 3 O] (space group Pnma, a = 589.5(3), b = 962.8(5), c = 1186.6(6) pm, Z = 4, R1 = 0.0494) contains anions [VS 3 O] 3− almost identical to those known from the high temperature form, β -Na 3 [VS 3 O] (space group Cmc2 1 , a = 968.4(4), b = 1194.6(4), c = 590.5(2) pm, Z = 4, R1 = 0.0291). The second order phase transition between these two forms at 536 °C was studied by temperature dependent powder diffraction and explained on the basis of a comparison of the anion packing in the two related structures. The packing of the dithiodioxovanadate anions in Na 3 [VS 2 O 2 ] (space group Pbca, a = 1162.7(2), b = 592.71(12), c =1766.7(4) pm, Z = 8, R1 = 0.0312) is also closely related. The chemical bonding in the anions [VS 3 O] 3− and [VS 2 O 2 ] 3− of approximately ideal C 3v and C 2v symmetry is discussed on the basis of FP-LAPW band structure calculations and force constants obtained from Raman spectroscopy. The decrease of the calculated band gaps with increasing S content x in Na 3 [VS x O 4−x ] is in accordance with the optical properties showing a gradually deepening of the crystal and solution colour. Discernible trends in the chemical bonding in this series of mixed thio-oxo anions also include the amount of π bonding of the V-O and V-S bonds and the corresponding variation of force constants and V-O/V-S distances.

The technologically important S-phase precipitate MgCuAl 2 has been synthesized from the elements in a sealed tantalum tube in an induction furnace. The aluminide was investigated by powder and single crystal X-ray diffraction methods: Cmcm, a = 401.19(9), b = 926.5(2), c = 712.4(1) pm, wR2 = 0.0425, 234 F 2 values, and 16 variable parameters. The new crystallographic data fully confirm the original work by Perlitz and Westgren [Ark. Kemi, Mineral. Geol. 16, 1 (1943)], but the present structure refinement has led to a much higher precision. The crystal chemical peculiarities of MgCuAl 2 are briefly discussed.

The ternary ordered Laves phases CeNi 4 Cd and RECu 4 Cd (RE = Ho, Er, Tm, Yb) were synthesized by induction-melting of the elements in sealed tantalum tubes. The compounds were characterized by X-ray powder and single crystal diffraction: MgCu 4 Sn type, F 4̄3m, a = 706.9(2) pm for CeNi 4 Cd, a = 723.1(2) pm for HoCu 4 Cd, a = 717.7(3) pm for ErCu 4 Cd, a = 714.2(1) pm for TmCu 4 Cd, and a = 713.10(7) pm for YbCu 4 Cd. The nickel and copper atoms build up threedimensional networks of corner-sharing Ni 4/2 and Cu 4/2 tetrahedra. These networks leave voids of coordination number 16 that are filled with the rare earth (RE) and cadmium atoms.

A new rare earth carbide boride halide, La 3 Cl 3 BC, has been prepared by heating a mixture of stoichiometric quantities of LaCl 3 , La, B and C at 1050 °C for 10 days. La 3 Cl 3 BC (La 3 Br 3 BC type) crystallizes in the monoclinic system with space group P2 1 /m (No. 11), a = 8.2040(16), b = 3.8824(8), c=11.328(2)Å , β =100.82(3)°. In the structure, monocapped trigonal prisms containing B-C units are condensed into chains along the b direction, and the chains are further linked by Cl atoms in the a and c directions. The condensation results in a polymeric anion 1 ∞ [BC] with a spine of B atoms in a trigonal prismatic coordination by La, and the C atoms attached in a square pyramidal coordination. The B-B and B-C distances are 2.16 and 1.63 Å , respectively. La 3 Cl 3 BC is metallic. The EH calculation shows that the distribution of valence electrons can be formulated as (La 3+ ) 3 (Cl − ) 3 (BC) 5− · e − .

Cobalt(II) and zinc(II) complexes of ethyl carbazate (ECZ), [Co(ECZ) 3 ](NO 3 ) 2 and [Zn(ECZ) 3 ] (NO 3 ) 2 , were synthesized. Single crystals of these two compounds were grown from aqueous solutions using a slow evaporation method. Their structures have been determined by X-ray diffraction analysis. Both of them are monoclinic with space group P2 1 /n. The complexes are further characterized by element analysis and IR measurements. Their thermal stabilities are studied by using TG-DTG, DSC techniques. When heated to 350 °C, only metal oxide was left for both complexes.

1,4-Dimethyl-2,5-di(phosphinyl)benzene (1) was prepared in high yield in a four-step synthesis from 1,4-dibromo-2,5-dimethyl-benzene. The intermediates with (Et 2 N) 2 P and Cl 2 P groups (2, 3) with the corresponding substitution pattern have been isolated and structurally characterized. All three compounds (1 - 3) adopt a centrosymmetrical conformation with one of the P-X bonds of each X 2 P group located in the ring plane while the other reaches out from this plane in a roughly perpendicular orientation. Distortions of the ring and its substituents from a standard planar hexagonal geometry are readily explained by invoking steric and inductive effects. The crystal structure of 1,4-dibromo-2,5-dimethyl-benzene has also been determined for reference purposes. Compound 1 was employed as a substrate for auration by tri(gold)oxonium salts of the type {[(R 3 P)Au] 3 O}BF 4 . Hexanuclear complex salts of the type {[(R 3 P)Au] 3 P(C 6 H 2 Me 2 )P[Au(PR 3 )] 3 }(BF 4 ) 2 were obtained in almost quantitative yield with R 3 P = t Bu 3 P (4) and Ph 3 P (5). The former (4) has the higher thermal stability, it could be crystallized and its structure determined. It features a conformation in which the xylene plane bisects one of the Au-P-Au angles at both tetrahedrally coordinated central phosphorus atoms placing its methyl groups in sterically least hindered positions. Compound 5 is labile in solution and shows rapid ligand exchange on the NMR time scale. The limited stability has also been confirmed by mass spectrometry. Similar structural details and differences in stability were observed in the related trinuclear gold complexes based on 1-naphthyl-phosphine, which were prepared as reference materials using the same preparative procedure. Of the two compounds {(1-C 10 H 7 )- P[Au(PR 3 )] 3 }BF 4 , with R 3 P = t Bu 3 P (6) and Ph 3 P (7), the former is the more stable species. In the solid state the cation approaches mirror symmetry in a conformation comparable to that of 4. Compound 7 is thermally labile and shows a rapid ligand exchange in solution.

The μ-bis(tetradentate) ligand, [C 27 H 26 Cl 3 N 4 O 4 ], H 3 L′, 1,3-bis[N-(5-chloro-2-hydroxybenzylidene)- 2-aminoethyl]-2-(5-chloro-2-hydroxyphenyl)imidazolidine and its mononuclear iron(III) complex, [Fe(L)](ClO 4 ), L = N, N′-bis(5-chloro-2-hydroxybenzylidene)-triethylenetetramine have been synthesized and their crystal structures determined. Minimum energy conformations of the ligand were calculated (MOPAC, AM1) as a function of two torsion angles and the results compared with optimized crystal structure. The ligand (H 3 L′) reacts with Fe(ClO 4 ) 2 · 6H 2 O in aqueous methanol to form the mononuclear [Fe(L)](ClO 4 ) complex with the imidazolidine ring cleaved by hydrolysis. The complex has an N 4 O 2 donor atom set forming a distorted octahedral coordination geometry around the metal atom as established from a crystal structure determination. The terminal oxygen donor atoms occupy cis positions, and the remaining four nitrogen atoms (two cis amine and two trans imine) complete the coordination sphere.

Cyclopentadiene reacts with five equivalents of 4-methylbenzylalcohol (1:5,6 mole ratio) and sodium yielding penta(4-methylbenzyl)cyclopenta-2,4-diene (1), which upon treatment with butyl lithium affords the lithium salt [(4-MeC 6 H 4 CH 2 ) 5 C 5 ]Li (2). The reactions of 2 with FeCl 2 and SnCl 2 result in the formation of deca(4-methylbenzyl)ferrocene (3) and deca(4-methylbenzyl)stannocene (4), respectively. The 1 H and 13 C NMR, IR and mass spectra of the new compounds as well as the single crystal X-ray structure analysis of 1 are reported and discussed.

Lu(CH 2 SiMe 3 ) 3 (THF) 2 (2) decomposes slowly at room temperature with formation of Me 4 Si. In order to understand the mechanism of this elimination process, Lu(CH 2 SiMe 3 ) 3 ([D 8 ]-THF) 2 (1), Lu(CH 2 SiMe 3 ) 3 (THF)(DME) (3), and Lu(CH 2 SiMe 3 ) 3 (THF)(diglyme) (4) were prepared. The results of 1 H NMR spectroscopic studies of the decomposition in solution exclude an α- as well as a β -H elimination mechanism and point towards a γ -H elimination. The molecular structure of 4 has been determined by single crystal X-ray diffraction.

The crystals of two isostructural uranyl selenates, M[(UO 2 )(SeO 4 ) 2 (H 2 O)](H 2 O) 4 (M = Mg, Zn), have been prepared by water evaporation from aqueous solutions. The structures have been solved by direct methods (M = Mg: P2 1 /c, a = 8.4666(8), b = 11.6306(14), c = 13.1669(12) Å , β = 90.959(7)°, V = 1296.4(2) Å 3 , R 1 = 0.061; M = Zn: P2 1 /c, a = 8.4492(18), b = 11.5860(17), c = 13.240(3) Å , β = 92.382(18)°, V = 1294.9(4) Å 3 , R 1 = 0.074). The structures are based upon [(UO 2 )(SeO 4 ) 2 (H 2 O)] 2− chains running parallel to the b axis and consisting of corner-sharing [UO 6 (H 2 O)] 6− pentagonal bipyramids and [SeO 4 ] 2− tetrahedra. The equatorial planes of the uranyl pentagonal bipyramids are oriented approximately parallel to (001). The uranyl selenate chains are linked into sheets parallel to (010) by [M(H 2 O) 6 ] 2+ octahedra which share common H 2 O molecules with the [UO 6 (H 2 O)] 6− pentagonal bipyramids.

The [Cu(C 6 H 2 Br 2 ClO) 2 (NH 3 ) 2 ] complex was synthesized and characterized by XRD, UV/vis, FTIR, DSC, elemental analysis and magnetic susceptibility measurements. The structural analysis of the title complex indicated that it is a monomeric centrosymmetric compound which crystallizes in the monoclinic system, P2 1 /c, and has a trans-planar CuO 2 N 2 coordination [Cu-O 1.940(5) and Cu-N 1.978(7) Å ]. In the coordination sphere of the Cu atom, there are long range interactions with Br 2 and the centrosymetrically related Br2i (i: −x,−y,−z) atoms [Cu-Br2: 3.079(2) Å ], resulting in a tetragonally elongated octahedral structure for the CuO 2 N 2 Br 2 coordination. The molecules form one-dimensional chains along the x-axis of the unit cell held together by intermolecular hydrogen bonds.

The known nor-diterpene (16R)-ent-17-hydroxy-19-nor-kaur-4-en-3-one and the new norditerpene (16R)-ent-19-nor-kaur-4-en-3-oxo-17-oic acid were obtained as a crystalline mixture from roots of C. ghiesbregthiana. Their structures were deduced by spectroscopic means and confirmed by a X-ray diffraction study of the crystalline mixture. Additionally, ursolic and betulinic acids, skimmin, and sucrose were isolated. This is the first chemical study of a member of the Coutaportla genus.

A new depside, erodiol, was isolated and identified from the aerial parts of Erodium cicutarium (Geraniaceae), together with essential compounds such as: geraniin, didehydrogeraniin, corilagin, (-) 3-O-galloylshikimic acid, methyl gallate 3-O-β -D-glucopyranoside, rutin, hyperin, quercetin 3- O-(6”-O-galloyl)-β -D-galactopyranoside, isoquercitrin and simple phenolic acids. Their chemical structures were elucidated by means of spectroscopic (ESI MS, HRESI MS, 1D and 2D NMR) evidence.

The twigs of Rhadinothamnus rudis ssp. amblycarpus (Phebalium rude ssp. amblycarpum) yielded three new 3-substituted coumarins: rudicoumarin A-C (1- 3). Their structures were established on the basis of their NMR and mass spectral data. In addition, ten other known compounds were also isolated, including phebaclavin I, schinicoumarin, seselin, and seven linear furocoumarins.

A new nitrogenous metabolite with p-terphenyl core, sarcodonin δ (1), together with two known p-terphenyl metabolites (7, 8), was isolated from the fruiting bodies of the basidiomycete Sarcodon scabrosus. The structures of these compounds were elucidated by spectral and chemical methods.

Selenourea reacts with dialkyl acetylenedicarboxylates under solvent-free conditions to form 1:1 adducts, which undergo a cyclization reaction to produce alkyl Z-2-(2-amino-4-oxo-1,3-selenazol- 5(4H)-ylidene)acetates, in good yields. The stereochemistry of the ethyl Z-2-(2-amino-4-oxo-1,3- selenazol-5(4H)-ylidene)acetate was established by X-ray single crystal structure analysis. The reaction is completely stereoselective.

Diaryl disulfides undergo regioselective ring-opening of 1,2-epoxides in the presence of zinc powder and 3-4 mol-% of bismuth(III) trifluoroacetate or 1 mol-% of bismuth(III) triflate in molten tetrabutylphosphonium bromide (TBPB) to afford the corresponding β -hydroxy thioethers in good to excellent yields.

The root bark of Hippocratea excelsa afforded a new derivative of β -amyrin, which was identified as its ferulate, together with components new in this species. They were identified as the rare 29-hydroxytaraxerol, 29-hydroxyglutinol, 29-hydroxyfriedelin and the sterol 6β -hydroxystigmast-4- en-3-one. The known triterpene quinone methides pristimerin and tingenone characteristics of this genus, β -sitosterol, trans-polyisoprene, squalene, β -amyrin, and the alditol galacticol characteristic of the Celastraceae were also isolated. The structures were established on the basis of spectral analysis, including homo- and heteronuclear correlation NMR experiments (COSY, DEPT, HMQC and HMBC) and by comparison with data reported in the literature. The structure of 29-hydroxytaraxerol was confirmed by X-ray diffraction. The antimicrobial and antifungal activities of the compounds were studied, but no significant activity was found.

In addition to the known furanones 1 and 2, the aerial parts of the shrub Mutisia friesiana afforded a new prenylated furanone, Mutisifuranone A (3), together with the known triterpenoids oleanic (4) and ursolic (5) acids and some sesquiterpenoids and n-alkanes. Their structures were elucidated by spectroscopic methods.

The 1,1-ethylboration of dichloro(hexyn-1-yl)silane, Cl 2 Si(H)-C≡C-Bu, affords selectively an alkene which is the first example with dialkylboryl and dichlorosilyl groups in cis-positions at the C=C bond. The analogous reaction of dichloro( trimethylsilylethynyl)silane, Cl 2 (H)Si-C≡C-Si Me 3 , leads to a 4:1 mixture of alkenes, in one of which the boryl and dichlorosilyl groups are in trans-positions. The alkenes were characterized by a consistent set of NMR data.