Volume 45, Issue 5

Using 293 K diffractometer intensity data, the crystal structure of [(CH 3 ) 2 HN(C 6 H 4 )NH(CH 3 )2]TeCl 6 has been determined by single crystal X-ray technique and refined to a final R w of 0.022. The yellow crystals are orthorhombic, space group Pna 2 1 , with a = 17.565(2), b = 8.4496(6), c = 12.572(1) Å and Z = 4. The TeCl 6 2- anions show a strong statical distortion with Te—Cl distances from min. 2.39 to max. 2.78 A. The symmetry rules for the stereochemistry of the lone pair electrons in AX 6 E-systems are confirmed. The influence of hydrogen bonding on the type of distortion is also discussed.

The reaction of CpFe(CO) 2 Me with (+)-Glyphos and (–)-Diop yields the monosubstitution products 1 and 2, which consist of pairs of diastereomers, differing only in the Fe configuration. With (–)-Diop, additionally dinuclear complexes are formed in which Diop acts as a bridging ligand. The diastereomers can be separated by column chromatography. At higher temperatures the complexes epimerize in solution with respect to the Fe configuration. The formation of free phosphine and CpFe(CO) 2 Me indicates a dissociative mechanism.

The polymorphic behaviour of Ba(BrO 3 ) 2 and Sr(IO 3 ) 2 is studied by means of differential thermal analyses and high-temperature X-ray and Raman spectroscopic measurements. On dehydration of the respective monohydrates [Ba(ClO 3 ) 2 · H 2 O type] at low temperatures in a vacuum Ba(BrO 3 ) 2 I and α-Sr(IO 3 ) 2 (both α-Ba(IO 3 ) 2 type, space group C2/c, Z = 4) are formed. On heating these polymorphs above 145 and 240 °C, respectively, phase transitions to Ba(BrO 3 ) 2 II [Sr(ClO 3 ) 2 type] and the hitherto unknown γ-Sr(IO 3 ) 2 occur. On further heating Ba(BrO 3 ) 2 II decomposes [partly via the high-temperature polymorph Ba(BrO 3 ) 2 III] to BaBr 2 and O 2 , γ-Sr(IO 3 ) 2 via the probably only stable polymorph β-Sr(IO 3 ) 2 to iodine and strontium paraperiodate. The IR and Raman spectra of Ba(BrO 3 ) 2 I and III, α-, β- and γ-Sr(IO 3 ) 2 , and α-Ba(IO 3 ) 2 are given. The crystal structure of Ba(BrO 3 ) 2 I has been determined by single crystal X-ray diffraction. The final R value for 1586 reflections with I ≥ 2σ I is 0.064. The crystal structures of the a-Ba(IO 3 ) 2 type anhydrous halates are very similar to those of the Ba(ClO 3 ) 2 · H 2 O type halate monohydrates.

Crystalline Na[MnF 4 (H 2 O) 2 ] and Na[MnF 4 (H 2 O)2] · H 2 O have been precipitated from aqueous HF solution of MnO(OH) and NaF. The crystal structure determination of the trihydrate (space group C 2/c, Z = 8, α = 1638.1(2), b = 667.6(2), c = 1130.3(1) pm, β = 103.78(1)°; R/wR = 0.038/0.033 for 1696 independent reflections) showed the presence of isolated octahedral trans-[MnF 4 (H 2 O) 2 ] - anions with an elongation of the H 2 O-Mn—OH 2 axis due to the Jahn-Teller effect (Mn 1-O 224.6(2), Mn 1—F(mean) 183.7(1); Mn2-0 218.3(2), Mn2— F(mean) 184.7(2) pm). As a consequence, an unusual H-bond geometry is observed with a tetrahedral (instead of trigonal) environment of the coordinated O atoms. Na[MnF 4 (H 2 O)2] is monoclinic (space group C 2/m, C 2 or Cm, a = 816.6(4), b = 677.1(1), c = 496.8(2), β = 114.45(3)°), the crystals show twinning and 1-dimensional disorder.

The polymorphism of CeVO 4 was investigated at high pressures and temperatures in a Belttype high-pressure apparatus. In addition to the normal-pressure modification CeVO 4 — I with zircon-type structure two high-pressure modifications have been found, viz. monazite-type CeVO 4 —II and scheelite-type CeVO 4 —III. CeVO 4 —II is stable between 1 bar and 30 kbar at 1300 °C. Its region of existence decreases rapidly at lower temperatures. From the observed p,T-relations for the I-II and I-III transformations a triple point CeVO 4 —I,II,III at about 27 kbar, 500 °C can be estimated. For kinetic reasons, however, the experimental determination of phase relations becomes difficult at temperatures below 600 °C. The crystal structures of CeVO 4 — I and —II have been refined from single-crystal data. Crystallographic data for the three modifications are given and discussed (CeVO 4 —I: I 4 1 /amd, a = 7.383(1)Å, c = 6.485(1)Å, Z = 4; CeVO 4 —II: P2 1 /n, a = 7.003(1)Å, b = 7.227(1)Å, c = 6.685(1)Å, β = 105.13(1)°, Z = 4; CeVO 4 —III: I 4 1 /α, a = 5.1645(2)Å, c = 11.8482(7)Å, Z = 4).

(CH 3 NH 3 ) 3 PrCl 6 · 2 H 2 O has been prepared as light green, air sensitive crystals by the reaction of PrCl 3 ·xH 2 O with [CH 3 NH 3 ]Cl in ethanol. The compound was characterized by crystal structure determination. Crystal data: monoclinic space group I 2/a, Z = 8. Lattice constants: a = 1963.3(4), b = 925.9(3), c = 1954.3(4) pm, β = 90.56(1)°. The compound forms [PrCl 4 (H 2 O) 2 ] - -chains where two Pr 3+ -ions are connected via two chlorine atoms. The magnetic behaviour of (CH 3 NH 3 ) 3 PrCl 6 · 2H 2 O has been studied.

A series of binuclear, hydroxyl-bridged copper(II) complexes 1-10 with the general formula [Cu 2 (LR 2 D 2 )(OH)](ClO 4 ) 2 was prepared and characterized. The mono basic, five- or sevendentate ligands HLR 2 D 2 were obtained either by reduction of the Schiff bases derived from the condensation of 2,6-diformyl-4-methylphenol and the amines H 2 N – D (complex 1: D = -(CH 2 ) 2 -NH 2 ; 2: -(CH 2 ) 2 -NMe 2 ; 3: -(CH 2 ) 2 -NEt 2 ; 4: -(CH 2 ) 3 -NEt 2 ; 5: -(CH 2 ) 2 -4-imidazolyl; 6: -CH 2 -2-pyridyl; 7: -(CH 2 ) 2 -2-pyridyl) or by reacting 2,6-di-(chloromethyl)-4-methylphenol with 2-[(2-methylamino)ethyl]pyridine (complex 8), Ν,Ν,N′,N′-tetraethyldiethylenetriamine (complex 9) or bis[2-(2-pyridyl)ethyl]amine (complex 10) under HC1 elimination. The UV/VIS spectra of complexes 1-8 with two four-coordinate copper centers and of 9 and 10 with two five-coordinate copper centers are discussed. An X-ray structure analysis of complex 6 (= [Cu 2 (LR 2 D 2 )(OH)](ClO 4 ) 2 with R = H and D = -CH 2 -2-pyridyl) was carried out. 6 crystallizes in the orthorhombic space group Pbca and the two copper centers have practically co-planar, doubly O-bridged cis-N 2 O 2 coordination geometries with one perchlorate anion being weakly coordinated to each copper. Stopped-flow spectrophotometry was used to study the kinetics of copper removal from [Cu 2 (LR 2 D 2 )(OH)] 2+ with EDTA in the pH range 8.5-6.6 at 20 °C and I = 0.2 M (NaClO 4 ). The reaction is first-order in both complex and EDTA, the rate law being: rate = k[complex][EDTA] total . At pH 8.0 second-order rate constants k range from 40.3 x 10 3 M -1 s -1 (complex 6) to 3.72x 10 -2 M -1 s -1 (complex 9). It follows from the pH dependence of k that both species H 2 EDTA 2- and HEDTA 3- react independently with [Cu 2 (LR 2 D 2 )(OH)] 2 +, the reactivity of H 2 EDTA 2- being considerably greater than that of HEDTA 3- . The experimental facts support the operation of an associative (A) mechanism with the removal of the first copper being rate-controlling. The kinetic effects of the donor group D and substituent R are attributed to steric and/or electronic interactions.

The reactivity of LMO 3 and L′MO 3 complexes as ligands has been investigated (L = C 6 H 15 N 3 , 1,4,7-triazacyclononane; L′ = C 9 H 21 N 3 , N,N′,N″-trimethyl-1,4,7-triazacyclononane; M = Mo VI , W VI ). The crystal structures of [(L′MoO 3 ) 4 Co II ][BPh 4 ] 2 · C 2 H 5 OH (1) and [(L′MoO 3 ) 4 Fe III ][BPh 4 ] 3 · Na[BPh 4 ] (2) have been determined by X-ray crystallography. Both the Co II and Fe III centers are in a tetrahedral environment of four oxygen atoms which are connected to L′MO 2 fragments. The reaction of LMO 3 complexes (M = Mo VI , W VI ) in aqueous solution with tetraphenylborate(1–) anions yields LMO 3 BPh 3 or [(LMO 3 ) 2 BPh 2 ][BPh 4 ] complexes and benzene. The crystal structures of LWO 3 BPh 3 (3) and [(LWO 3 ) 2 BPh 2 ][BPh 4 ] (4) have been determined.

Using a modified cyanide process RbAu(CN) 2 was synthesized by the reaction of gold powder with RbOH, O 2 and liquid HCN. The colourless crystals are monoclinic, space group C2/c, with a = 18.450(3), b = 8.998(2), c = 13.418(2) Å, β = 108.0(9)° and Z = 16. The structure could be solved by Patterson and standard direct methods and refined to R = 0.035 and Rw = 0.034, respectively, for 857 absorption-corrected unique reflections. The structure comprises layers of linear [Au(CN) 2 ] - groups, in which gold atoms are arranged in four- and eightmembered rings. The stacking of the layers with a sequence ABAB creates different kinds of holes which are occupied by the rubidium ions.

(NEt 4 )[MesCr(CO) 2 N 3 ] (1) (Mes = mesitylene), (NEt 4 )[TDMCr(CO) 2 N 3 ] (2) (TDM = terephthalic acid dimethyl ester) and (NEt 4 )[CpRe(CO) 2 N 3 ] (3) (Cp = η 5 -cyclopentadienyl) were obtained from the corresponding [AreneCr(CO) 2 THF] complexes and [CpRe(CO) 2 THF], respectively, and NEt 4 N 3 . 1 and 2 decompose above —10 °C and 3 is light sensitive. Attempts to obtain new nitrogen ligands which are unstable in free state by reacting the azido complexes with H + , Me + and NO + , respectively, led preferably to the N 2 complexes [AreneCr(CO) 2 N 2 ] and [CpRe(CO) 2 N 2 ], respectively, and decomposition products.

Normal coordinate analyses for the ten isotopomers Cs 2 11 B n 10 B 6-n H 6 , n = 0 — 6, including the pairs of geometric isomers for n = 2, 3, 4 have been performed, based on a general valence force field. The shift of the bands as well as the splitting of degenerate modes by lowered symmetry due to exchange of 10 B by 11 B or H by D is exactly calculated by a set of six force constants. The characteristic band patterns observed in the IR and Raman spectra of Cs 2 B 6 H 6 with natural abundance of B isotopes (80.22% 11 B, 19.78% 10 B) measured at 10 K are explained by the superposition of the calculated spectra of the different isotopomers present, according to their statistical frequency distribution. The calculated atomic displacements and the potential energy distribution on the symmetry coordinates reveal only a small coupling (PED < 10%) between the cage (in-phase displacements of H and B) and substituent vibrations (anti-phase motions of B and H). Based on the normal coordinate analyses previously obtained assignments for several bands are revised.

Of several methods tested to improve the yield of the metal carbonyl OsCo 2 (CO) 11 (1), the reaction of H 2 Os(CO) 4 with Co 2 (CO) 6 μ-C 2 H 2 ) was found to give the best results (>50%). The availability of 1 allowed to study its capping reactions with C 2 H 4 S, PhPH 2 and alkynes RC≡CH leading to the products OsCo 2 (CO) 9 (μ 3 -X) for X = S (2), PPh (3), and RC=CH (4). The capped clusters are thermally more stable than the corresponding RuCo 2 (CO) 9 derivatives, and the alkyne capped species are more difficult to transform to the vinylidene capped clusters OsCo 2 (CO) 9 (μ 3 -C=CHR) (5) than the analogous RuCo 2 species.

The polarized optical emission (energy, intensity, lifetime) of the red modification of singlecrystal Pt(bpy)Cl 2 as a function of temperature (1.9 ≤ T ≤ 298 K) and homogeneous magnetic fields (0 ≤ H ≤ 6 T), and the temperature dependence of the polarized optical absorption are reported. Analysis of the spectra indicates a strong inter-complex coupling giving rise to electronic band structures and self-trapped states.

Mononuclear and binuclear compounds [(C 5 Me 5 )Ru(η 6 -arene)PF 6 and [(C 5 Me 5 Ru) 2 (η 6 ,η 6 -arene)](PF 6 ) 2 were prepared by reacting (C 5 Me 5 )RuCl 2 , the arene and silver acetate with subsequent addition of NH 4 PF 6 , for arene = phenanthrene, chrysene, triphenylene, fluorene, bifluorene, biphenyl and 4,4′-biphenyl. The mononuclear compounds were also prepared for arene = naphthalene, anthracene, pyrene and coronene. The 1 H and 13 C NMR spectra are reported. By cyclic voltammetry all compounds show a first reduction potential that is considerably more positive compared with the free arene. The first cathodic wave is irreversible for a wide range of scanning speeds. However, the mononuclear coronene and the binuclear phenanthrene compounds show reversibility. The crystal structure of [(C 5 Me 5 )Ru(η 6 -chrysene)]PF 6 ·0.5 Me 2 CO was determined by X-ray diffraction (3797 unique observed reflexions, R = 0.098). Crystal data: a = 1689.2(2), b = 1524.0(8), c = 2263.5(3) pm, β= 107.22(1)°, space group P2 1 /n, Ζ = 8. Crystallographically independent, two cations [(C 5 Me 5 )Ru(η 6 -chrysene)] + and two anions PF 6 - are present, but their structures are essentially equal. The [C 5 Me 5 Ru] + unit is bonded to one of the terminal benzene rings of the chrysene in a sandwich manner; the rings bonded to Ru are nearly coplanar. The PF 6 - ions and the C 5 Me 5 rings exhibit strong thermal vibrations.

The pseudobinary systems ETe — ETeHal (E/Hal = Al/I, Br; Ga/I, Br, Cl; In/I, Br) contain the intermediate phases E 3 Te 3 Hal, having incongruent melting behavior (decomposition at temperatures between 386 °C and 718 °C). The crystal structures (orthorhombic, Pnma) of the isotypic ternary phases contain one-dimensional macromolecules, in which (Te 3/3 E III Hal)-tetrahedra and (Te 3/3 Ga 2 II Te 3/3 ) units (staggered conformation) are linked by common Te—Teedges. The macromolecules can be described in terms of fragments of an ETe-crystal structure of the GaTe structural type. In this way, halogen acts as an oxidizing agent which then saturates the free valence at the E III positions. Larger fragments of a respective ETe-crystal structure are expected to be present in the crystal structure of InTeCl (x ≈ 0.16) which is an intermediate phase (m. p. = 418 °C; incongruent) in the quasibinary system InTe — InTeCl.

N,N-Dimethylformamidinium-halometallates(I), [(DM F) 2 H][Me 3 X 4 ] with Me 3 X 4 = Cu 3 I 4 - , Cu 3 I 2 Br 2 - , Cu 3 I 3 Cl - , Ag 2 CuI 4 - , Ag 3 I 4 - , Ag 3 I 3 Br- and Ag 3 I 3 Cl - were obtained by reacting Cul or Agl with HI, HBr or HC1 in DMF. The crystal structures of the isostructural compounds (space group Pccn) are built by hydrogen-bridged DMF molecules, (DMF) 2 H+, as cations and a new type of polymeric anion formed by edge sharing tetrahedra triple chains. The chains consist of a double layer of halogen atoms where Cu(I) and Ag(I) cations are located in tetrahedral holes. There are two kinds of halogen positions in the chains. One of them bridges two metal ions, the other is coordinated by four metal ions. In the anion chains ∞ 1 ,[Cu 3 I 2 Br 2 - ], ∞ 1 [Cu 3 I 3 Cl - ], ∞ 1 [Ag 3 I 3 Br - ] and ∞ 1 [Ag 3 I 3 Cl - ] the lighter halogen atoms occupy the positions bridging two metal ions. The O—H—O distances range from 235-243 pm. They indicate strong hydrogen-bonding between the two DMF molecules in the (DMF) 2 H + cations.

[Ag(PhN 3 C 6 H 4 N3(H)Ph)] 4 is obtained by the reaction of AgNO 3 with [PhN 3 C 6 H 4 N 3 (H)Ph)]Na in tetrahydrofurane in form of brown crystals. The crystal structure determination (orthorhombic space group Pbcn, a = 1989.7(8), b = 1917.5(3), c = 1767.1(4) pm, Z = 4, 1784 reflections for 200 parameters, final R = 0.059) shows the complex to be isotypic to the previous described copper analogue. The complex is built of a rhombus of four silver atoms and four bridging bistriazenido units. One nitrogen atom of a neutral nitrogen chain completes the coordination sphere of each silver atom to a distorted trigonal bipyramidal environment of two other silver atoms and three nitrogen atoms. The Ag–Ag distances are in the range from 279.9 to 310.3 pm, the Ag–N distances from 217 to 236 pm.

(PPh 4 ) 2 [Mn(Se 4 )2] has been prepared by the reaction of a lithium poiyseienide solution in DMF with MnCl 2 .4H 2 O at 100 °C in the presence of PPh 4 Br. The compound forms black crystals, which were characterized by IR spectroscopy as well as by an X-ray structure determination. Space group P2 1 , Z = 4, 3622 observed unique reflexions, R = 0.076. Lattice dimensions at 19 °C: a = 1017.2(3), b = 1405.9(3), c = 3427.7(8) pm, β = 92.04(2)°. The compound consists of PPh 4 ⁺ and [Mn(Se 4 ) 2 ] 2- ions, in which the manganese atom is tetrahedrally surrounded by four selenium atoms of two chelating Se 4 2- units. The structure is isotypical with that of (PPh 4 ) 2 [Zn(Se 4 ) 2 ].

Synthesis of the new sterically hindered pyridine-1-oxides 2c and 6a–c is described. Copper(II)-catalyzed photolysis of 2 and 6a in aqueous medium provides only small amounts of 2-acylpyrroles 8 and 10a together with by-products. Exclusive formation and better yields of 10 can be received upon irradiation of 6 in none protic solvents at low temperature. Introduction of bulky substituents as in 6 failed to stabilize any of the postulated intermediates in order to be identified during photoreaction. It is assumed that the high rate of polymerization is caused by unstable 1,3-oxazepines like 13.

N-Arylphthalisoimidium perchlorates (1 a, b) react with primary amines via ring-opening to give N,N′-disubstituted phthalamides (3a—d). They react with aromatic hydrocarbons under Friedel-Crafts conditions to give 2,3-diaryl-3-hydroxyphthalimidines (a—i) while the reaction of 1 a with phenylmagnesium bromide involved just deprotonation to the isoimide (9) followed by rearrangement to N-phenylphthalimide (8).

A synthesis of 11,19-oxidopregn-4-ene-3,20-dione and 6,19-oxidopregn-4-ene-3,11,20-trione is described starting from pregn-4-ene-3,11,20-trione and via the common intermediate 3β,20β-diacetyloxy-5α-bromo-6,19-oxidopregnan-11-one, in 30 and 32% yield, respectively.

Homoconjugation energies in vacuo have been calculated for pyridine N-oxide (PyO) and its 4-methyl- (4 PicO) and 4-nitro- (4-NO 2 PyO) derivatives with the use of the CNDO/2 method. Comparison with the experimental homoconjugation constants in some aprotic solvents reveals the opposite order of the stability of homocomplexes than could be expected based on the calculated homoconjugation energies. This formal inconsistency can be explained in terms of the solvation effect.

Using the n-PDQ model, in which the solvent is simulated by several point dipoles and quadrupoles, we have estimated the shift of the UV bands of pyridine N-oxide (PyO), its cationic acid (PyOH + ), and homoconjugated cation (PyOHPyO + ) caused by the solvent (acetonitrile). We have calculated the UV spectra of both unsolvated and solvated species by the CNDO/S-CI and CNDO/S-CI-nPDQ method, respectively. We have found that all the bands of all the species under study are blue-shifted on solvation. The most significant is the shift of the long-wave π→π* bands of pyridine N-oxide.

Tritiated compounds containing 2,2,2-trifluoroethyl groups were formed by the reaction of tritium atoms with trifluoroethylene. The result can be accepted as definitive evidence for a 1,2-fluorine atom migration occurring in the reaction intermediate, tritiated 1,1,2-trifluoroethyl radical.

Five samples (headspace, steam distillation, Likens-Nickerson, methanolic and dichloromethane extracts) of Austrian hay blossoms have been investigated by chromatographic-spectroscopic methods and led to the identification of several non or less volatile compounds (mainly in the Likens-Nickerson extract).