Volume 46, Issue 10

The crystal structures of isotypic Sr(OH)Cl ·4 H 2 O, Sr(OH)Br·4 H 2 O, and Ba(OH)I·4 H 2 O are reported. The title compounds crystallize in a hitherto unknown structure type, space group PĪ, Z = 2. The final R values obtained are 0.0261, 0.069, and 0.062, respectively. The coordination of the metal ions is monocapped square antiprismatic with 7 H 2 O, 1 OH - and 1 halide ion. The halide ions separate metal/water/hydroxide layers. Each of the four crystallographically different water molecules serves as donor for one very strong and one very weak hydrogen bond and, hence, is extremely asymmetrically bound. Owing to this strong distortion, the largest one known so far, the OH stretching vibrations of the H 2 O molecules are intramolecularly decoupled as shown from vibrational spectra. The enthalpies of dehydration obtained from differential scanning calorimetry are reported.

The title compound was prepared from sodium polyselenide and 12-crown-4 in DMF solution in the presence of cerium(III)chloride in the form of black needles. The crystal structure determination by X-ray diffraction shows a partially disordered structure, in which the anionic units Se 8 2- · Se 7 and Se 8 2- · Se 6 are present in the ratio 0.72/0.28. These units are associated to layers parallel to (100); the layers alternate with pseudohexagonal layers of [Na(12-crown-4) 2 ] + ions. Space group P1̅, Z = 2, 3903 observed unique reflections, R = 0.114, wR= 0.084. Lattice dimensions at -65°C: a = 1247.9(3), b = 1367.8(8), c = 1660(1) pm, α = 94.65(5), β = 98.94(3), γ = 91.10(3)°.

The title compounds have been prepared by the reactions of a potassium diselenide solution in DMF with excess selenium in the presence of tetraethyl and tetrapropyl ammonium chloride, respectively. They were characterized by X-ray crystal structure determinations. (NEt 4 + ) 2 [Se 5 2- ·1 /2 Se 6 · Se 7 ]: Space group PĪ, Z = 2, 2514 observed unique reflections, R = 0.085. Lattice dimensions at —40 °C: a = 957.7(4), b = 1384.2(4), c = 1545.3(7) pm, α = 107.32(3)°, β = 97.27(4)°, γ = 105.94(3)°. The compound has an ionic structure of NEt 4 + ions and chains of pentaselenide ions, which are associated with Se 6 and Se 7 , ring molecules, forming layers parallel to (110). (NPr 4 ) 2 Se 11 : Space group C2/c, Ζ = 4, 2198 observed unique reflections, R = 0.082. Lattice dimensions at —40 °C: a = 2364.7(5), b = 1206.8(2), c = 1609.6(3) pm, β = 118.74(3)°. The compound consists of cations (N(C 3 H 7 ) 4 + and spirocyclic anions Se 11 2- , in which two Se 6 rings having chair conformation are linked by a common Se atom with planar coordination. There are no short contacts between the S 11 2- ions.

The amidinato complex [Ph—C(NSiMe 3 ) 2 ] 2 FeCl has been prepared by the reaction of FeOCl with the amidine Ph—C(NSiMe 3 )[N(SiMe 3 )2] in acetonitrile/THF in the form of dark red moisture sensitive single crystals. The complex was characterized by IR spectroscopy, by its 57 Fe-Mössbauer spectra, as well as by an X-ray structure determination. Space group PI, Z = 2, 3180 observed unique reflections, R = 0.068. Lattice dimensions at —80°C: a = 1210.4(2), b = 1272.7(3), c = 1316.0(3) pm; α = 67.81(3)°, β = 76.14(3)°, γ = 67.19(3)°. The complex has a molecular structure in which the iron atom is surrounded in a distorted trigonal-bipyramidal fashion with the chlorine ligand and two nitrogen atoms of different amidinato chelates in equatorial positions. The remaining nitrogen atoms occupy the apical positions.

Tc 2 (O 2 CCH 3 ) 2 Cl 4 (H 2 O) 2 has been prepared by reaction of [Tc 2 Cl 8 ] 2- with acetic anhydride and fluoroboric acid. By treatment with the donor bases L = N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAA), dimethylsulfoxide (DMSO), triphenylphosphinoxide (TPO) and pyridine (Py), the green adducts Tc 2 (O 2 CCH 3 ) 2 Cl 4 L 2 are formed. The structure of Tc 2 (O 2 CCH 3 ) 2 Cl 4 (DMAA) 2 was determined by X-ray diffraction; space group C2/c with a = 29.604(4), b = 10.895(2), c = 14.404(2) Å, β = 97.87(2)°, Ζ = 8, Rw = 2.7%. The Tc-Tc distance is 2.1835(7) Å, the bridging acetate groups are in cis-positions. The IR and Raman spectra have been recorded at 80 K and assigned according to point group C 2v , supported by a normal coordinate analysis of Tc 2 (O 2 CCH 3 ) 2 Cl 4 (DMAA) 2 based on a general valence force field. The stretching interaction constant f d (TcTc) is determined to 3.38 mdyn/Å. With increasing donor strength of the axial ligands, the intense Raman vibration v(TcTc), showing up to three overtones, is lowered from 311 to 282 cm -1 . The δ-δ* transitions of all adducts are observed at 648-652 nm.

Single crystals of SrVO 3 , Sr 2 VO 4 and Sr 3 V 2 O 7 have been obtained by high-pressure reactions in a modified belt-type apparatus. The crystal structures, refined from diffractometer data, are as follows: SrVO 3 , perovskite type, Pm3̄m, a = 3.8408(3) Å, R = 0.017, R w = 0.018, composition from occupancy refinement of oxygen positions SrVO 2.93(2) ; Sr 2 VO 4 , K 2 NiF 4 type, I 4/mmm, a = 3.837(1), c = 12.569(1) Å, R = 0.014, R w = 0.017; Sr 3 V 2 O 7 , Sr 3 Ti 2 O 7 type, I 4/mmm, a = 3.839(1), c = 20.262(2) Å, R = 0.020, R w = 0.029.

Diorganobismuthacetylides R 2 BiC≡CR′ (R = C 6 H 5 , p-CH 3 C 6 H 4 , CH 3 ; R′ = CH 3 , C(CH 3 ) 3 , C 6 H 5 ) were prepared by reactions of R 2 BiBr with NaC=CR' in liquid ammonia. Reaction of two equivalents of NaC≡CR′ with RBiBr 2 leads to mixtures of R 2 BiC=CR′ and RBi(C=CR′) 2 .

The crystal and molecular structure of the title complex was determinated by single crystal X-ray diffraction (R = 0.066 for 1059 observed reflections). The approximately square-pyramidal coordination of Cu(II) results from donor atoms O(12), O(1), N(1), O(5) of one H 2 O molecule as well as the tridentate Schiff base dianion ligand and from the weakly bonded O(1) donor atom of one other H 2 O molecule in the apical site. The magnetic behaviour of the complex studied obeys the Curie—Weiss law in the temperature range 94—309 K with a small value of the Weiss constant, θ = 1.4 Κ. A similar cryomagnetic behaviour is also characteristic for the anhydrous compound, [N-salicylidene—(S)—(+)-glutamato]copper(II), obtained by thermal dehydration of the title complex.

The preparation of N,N′-bis(trimethylsilyl)benzamidinates of chromium, manganese, zinc and bismuth is described. The chromium(II) derivative [PhC(NSiMe 3 )2] 2 Cr (2) has been characterized by an X-ray structure determination. Treatment of CpTiCl 3 with one equivalent of Na[PhC(NSiMe 3 ) 2 ] · 0.5 Et 2 O yields the mixed Cp/benzamidinate complex [PhC(NSiMe 3 )2]CpTiCl 2 (9).

Complexes of the types cis-L 2 PtCl 2 (L = PPh 3 , 1/2 dppe) and cpRu(PPh 3 ) 2 Cl react with 1-alkyne-1-thiolates to give the products trans-(Ph 3 P) 2 Pt(S–C≡C–Ph) 2 (5), dppePt(S–C≡C–Ph) 2 (6) and CpRu(PPh 3 ) 2 (S–C≡C–Ph) (7), respectively. CpRu(PPh 3 )(CO)(S–C≡C–Ph) (8) is formed by reaction of 7 in an atmosphere of CO. The 2-propene-1-thiolato complexes dppePt(S–CH 2 –CH = CH 2 ) 2 (9), CpFe(CO) 2 (S–CH 2 –CH=CH 2 ) (12) and CpFe(PPh 3 )(CO)(S–CH 2 –CH=CH 2 ) (13) are obtained from dppePtCl 2 , CpFe(CO) 2 I, CpFe(PPh 3 )(CO)I and lithium or sodium 2-propene-1-thiolate. The complexes are characterized by IR and 1 H, 13 C and 31 P NMR spectroscopy.

The synthesis and structure of disulfane are presented. Pure disulfane, H 2 S 2 , has been obtained by the cracking distillation of raw sulfane mixtures in a rotary evaporator, thus substituting the classical cracking column for the rotating flask of the evaporator. Pure, gaseous dideuterodisulfane could be generated by the solvolysis of bis(methyldiphenylsilyl)disulfane, (MePh 2 Si) 2 S 2 , with D 2 O in the presence of trichloroacetic acid as stabilizing agent. Partially deuterated disulfane has been prepared by H,D exchange between pure H 2 S 2 and DCl. For the first time the molecular structure of HSSH has been determined based solely on microwave spectroscopy with the following parameters: r(SS) = 2.0564 A, r(SH) = 1.3421 A, dihedral angle γ = 90.34°, and <(SSH) = 97.88°.

In order to investigate how chirotopicity and stereogenicity of metal centers influence the enantioselectivity of metal centered reactions the stereogenic properties of metal centers in chiral complexes have to be varied without changing their electronic character. Diastereospecific alkylation of [Mo(NO) 2 (′S 2 ′ ) 2 ] 2- by racemic 1,2-dibromopropane and 1,2-dibromobutane yields the title complexes [Mo(NO) 2 (′MeS 4 ′ )] and [Mo(NO) 2 (′EtS 4 ′)] that differ from the parent compound [Mo(NO) 2 ('S 4 ′)] with respect to the stereogenicity of the metal center and allow future investigations of the question raised above.

Since substrate addition and elimination reactions are essential reactions of metal sulfur centres in oxidoreductases, we investigated the substitution of chloride in [Mo(Cl)(NO)(′S 4 ')](1) (′S 4′2- = 1,2-Bis(2-mercaptophenylthio)ethane(2-)) [4] and in the analogous tungsten complex [W(Cl)(NO)(′S 4 ')](2). The chloride ligands in 1 and 2 can easily be substituted by thiolates to give [M(SR)(NO)(′S 4 ')] (M = Mo, R = Me 3a,′Pr 3b, n Bu 3c, Ph 3d; M = W, R = Me 4a, Ph 4b). For these substitution reactions an associative mechanism is suggested. The SR - ligands act probably as σ-π four electron donor ligands to give metal centres with an 18 electron configuration as also found in the amido complexes [Mo(NR 2 )(NO)('S 4 ')] [4]. 1 and 2 react with PMe 3 to yield the adducts [M(PMe 3 )(Cl)(NO)('S 4 ')] (M = Mo 5, W 6), whose NMR spectra indicate the formation of two stereoisomers in a ratio of about 2:3.

A new method for the preparation of monoalkylamides of composition Cp′TiCl 2 NHR is reported. Me 3 SnNHR (R = tBu 1a, CHiPr 2 1b) reacts with Cp′TiCl 3 with elimination of Me 3 SnCl to yield Cp′TiCl 2 NHR (2) (2a: Cp′ = C 5 H 5 , R = tBu, 2b: Cp′ = Me 3 SiC 5 H 4 , R = tBu, 2c: Cp′ = (Me 3 Si) 2 C 5 H 3 , R = tBu, 2d: Cp′ = Me 4 C 5 H, R = tBu, 2e: Cp′ = Me 5 C 5 , R = tBu, 2f: Cp′ = C 5 H 5 , R = CHiPr 2 , 2g: Cp′ = Me 3 SiC 5 H 4 , R = CHiPr 2 , 2h: Cp′ = (Me 3 Si) 2 C 5 H 3 , R = CHiPr 2 , 2i: Cp′ = Me 4 C 5 H, R = CHiPr 2 , 2j: Cp′ = Me 5 C 5 , R = CHiPr 2 ). Compounds 2a-2j are stable and eliminate HCl only in the presence of a strong base to form (C 5 H 5 TiClNtBu) 2 (3a) or (Me 3 SiC 5 H 4 TiClNtBu) 2 (3b) from 2a and 2b, respectively. In 3a the chlorine atoms are substituted by NHtBu groups in boiling THF by means of LiNHtBu to give (C 5 H 5 TiNHtBuNtBu) 2 (4). The reactions of 2e and 2b with LiN(SiMe 3 ) 2 ·Et 2 O in the presence of pyridine yield Me 5 C 5 TiClNtBu · Py (5a) (Py = pyridine) and Me 3 SiC 5 H 4 TiClNtBu·Py (5b), respectively. Compounds 2e and 5a have been characterized by X-ray crystal structural analysis.

The complexes C 5 H 5 Co(PMe 3 ) 2 (1), C 9 H 7 Co(PMe 3 ) 2 (2) and (C 5 H 4 CF 3 )Co(PMe 3 ) 2 (3) react with mono- and disubstituted ethenes such as styrene, acrylic acid methylester, methylvinylketone, acroleine, acrylic acid amide, acrylonitrile, maleic anhydride, maleic and fumaric acid dimethylester, and fumaric dinitrile to give the olefin(phosphane)cobalt compounds (ring)Co(PMe 3 )(olefin) (4-32) in good to excellent yields. With acrylonitrile, two different rotamers are obtained which indicates that there is a considerable energy barrier for rotation around the metal-olefin bond. The reactions of 1 and 3 with maleic acid dimethylester (MDE) lead not only to the formation of the expected products (ring)Co(PMe 3 )(MDE) (22, 23) but also to the thermodynamically favored isomers (ring)Co(PMe 3 )(FDE) (24, 26) containing fumaric acid dimethylester (FDE) as ligand. A similar isomerization has been observed upon treatment of 2 and 3 with fumaric dinitrile (FDN) which gives besides the complexes (ring)Co(PMe 3 )(FDN) (29, 31) also the maleic dinitrile (MDN) derivatives (ring)Co(PMe 3 )(MDN) (30, 32). The olefin(trimethylphosphane)cobalt compounds are surprisingly inert and neither on photolysis nor on heating give the isomeric hydrido(vinyl)metal complexes.

Tricarbonyl-η 5 -2,4-cyclohexadien-1-yl-manganese (1) was reacted photochemically at 253 K with simple conjugated dienes. Four different types of products were obtained, depending upon the dienes. With 1,3-butadiene (A) dicarbonyl-η 4:3 -1-(3-buten-1,2-diyl)-2,4-cyclohexadiene-manganese (2A) is isolated. 2-Methyl-1,3-butadiene (B) yields the methyl-substituted diastereomeric dicarbonyls 2B, 2B′, the [4+5]-cycloadduct tricarbonyl-η 3:2 -3-methyl-bicyclo-[4.3.1]-3,8-decadien-7-yl-manganese (3B) and tetracarbonyl-η 3 -4-methylene-bicyclo[4.3.1]-8-decen-3-yl-manganese (4B) with an exocyclically coordinated tetracarbonylmanganese fragment. With 2,3-dimethyl-1,3-butadiene (C) only the [4+5]-cycloadduct 3C and the tetracarbonyl 4C are obtained. No CC-bond formation is observed with E,E-2,4-hexadiene (D) and 1,3-cyclohexadiene (E). Carbonyl-η 5 -2,4-cyclohexadien-1 -yl-η 4 -E,E-2,4-hexadiene-manganese (5D), and carbonyl-η 4 -1,3-cyclohexadiene-η 5 -2,4-cyclohexadien-1-yl-manganese (5E) are the only products. The complexes were separated and purified by HPL chromatography. Their constitutions were determined by IR and NMR spectroscopy.

[PdCl 2 (PPh 3 ) 2 ] reacts with Se(SiMe 3 ) 2 to form a mixture of multinuclear Pd complexes, [Pd 3 Se 2 (SeSiMe 3 ) 2 (PPh 3 ) 4 ] (1), [Pd 5 Se 5 (PPh 3 ) 5 ] (2) and [Pd 8 Se 8 (PPh 3 )8] (3). 1 can be used as starting material for the synthesis of further Pd clusters. Reactions of 1 with [CpCrCl 2 (THF)], [PdCl 2 (PPh 3 ) 2 ] and [NiCl 2 (PPh 3 ) 2 ] lead to the formation of [Pd 6 Se 4 Cl 4 (PPh 3 ) 6 ] (4), [Pd 8 Se 8 Cl(PPh 3 ) 8 ] + [CpCrCl 3 ] - (5), [Pd 5 Se 4 Cl 2 (PPh 3 ) 6 ] (6) and [Pd 7 Se 6 (SeH)Cl(PPh 3 ) 7 ] (7). The complexes [Pd 6 Se 4 (SeH) 2 Cl 2 (PPh 3 ) 6 ] and [Pd 6 Se 4 (SeH) 4 (PPh 3 ) 6 ] have structures similar to 4, and are formed by reaction of [PdCl 2 (NBD)] or [PdCl(COD)] 2 (BF 4 ) 2 with PPh 3 and Se(SiMe 3 ) 2 . Reaction of [(C 3 H 5 )PdCl] 2 with [NiCl 2 (PPh 3 ) 2 ] and S(SiMe 3 ) 2 leads to the formation of the heterometal cluster [Pd 4 NiS 4 Cl 2 (PPh 3 ) 6 ] (8). The molecular structures of 2-8 show quite clearly that these compounds may be considered as intermediates on the route towards multinuclear Pd complexes.

The structure of the (1,3-butadiene)M(R 2 PC 2 H 4 PR 2 ) compounds (M = Ni, Pd, Pt; R = Pr i , Bu′, Cy) in the solid-state have been investigated by 13 C and 31 P CP/MAS NMR spectroscopy. The bonding mode adopted by the diene is dependent upon the nature of the metal: the palladium compounds contain an η 2 -diene molecule, the nickel compound where R is cyclohexyl contains an η 4 -diene molecule whereas the Pr 2 i PC 2 H 4 PPr 2 i -stabilized platinum compound con- tains a platinacyclopentene ring. The crystal structures of (η 2 -1,3-C 4 H 6 )Pd(Cy 2 PC 2 H 4 PCy 2 ) and (η 4 -1,3-C 4 H 6 )Ni(Cy 2 PC 2 H 4 PCy 2 ) have been confirmed by X-ray diffraction.

Investigating the Belousov—Zhabotinskii (BZ) type reaction of an acidic L-ascorbic acid (AA) / potassium bromate / cerous sulfate system, an oscillatory effect of circular dichroism is detectable at λ = 300 nm. HPLC analysis of the oscillatory mixture and spectroscopic experiments indicate that this effect is caused by 3,4,5-trihydroxy-2-oxo-L-valeraldehyde (TVA) — a C 5 oxidation fragment of AA. Because of the bromide ion production occurring before the metal catalyst addition the AA system shows no preoscillatory phase and a rather short entire length of oscillation up to a maximum of 20 min. Since AA is not brominated but oxidized by bromine which is formed by the Landolt typ “clock reaction” of AA with acidic bromate, partially bromine-hydrolysis-controlled (BHC) oscillations are discussed for the overall mechanism of this BZ system.

Secondary enaminones 2 are easily halogenated to yield the so far unknown halogenides 3,4 and 5. Acyloxylation of enaminones 2 by dibenzoylperoxide leads to benzoyloxylated substances 13, which also have not been described jet. Bisacylated products could not be traced. Only the rearranged compounds 14 could be isolated. 14b showed cytotoxic activity.

The alcoholysis of epoxide 1 in acidic methanol leads to various products; one of these — hydroxymethoxyketone 7 — rearranges to the isomeric ketone 14 on contact with silica gel.

A simple and fast procedure was worked out to prepare from the commercially available seeds of Euphorbia lathyris L. substantial amounts of the polyfunctional tetracyclic diterpene ingenol (la). Ingenol-3,4:5,20-diacetonide (1d) was treated with five different bases at two different temperatures to achieve epimerization to 8-epiingenol. In any case unchanged 1 d was obtained. By reduction of ingenol-3,4: 5,20-diacetonide (1d) with sodium in ether/2-propanol (9 R)-9-deoxo-9-hydroxyingenol-3,4:5,20-diacetonide (2b) was obtained and converted to the corresponding 5,20-monoacetonide 2e. Reduction of ingenol-5,20-acetonide (le) with LiAlH 4 in tetrahydrofuran furnished the epimeric (9 S)-9-deoxo-9-hydroxyingenol-5,20-acetonide (3c).The (9 R)-monoacetonide 2e was used to prepare the 3-tetradecanoate 2c of (9 R)-9-deoxo-9-hydroxyingenol (2a). From the (9 S)-monoacetonide 3 c four 3-esters [butyrate (3d), tetradecanoate (3e), eicosanoate (3f), benzoate (3g)] of (9S)-9-deoxo-9-hydroxyingenol (3 a) were synthesized. The 3,4 : 5,20-diacetonides of 2a and 3a, i.e. 2b/3b were used to provide the 9-hexadecanoates 2 f and 3j. The irritant activities of the 3-esters of the (9 S)-series depend strongly on the nature of the acyl group, thus furnishing, e. g. the moderately irritant tetradecanoate 3e [compared to corresponding 3-esters lb of ingenol (la)] as well as the highly active benzoate 3g of 3 a. The (9 R)-3-tetradecanoate 2c exhibits comparable activity as its (9 S)-analogue 3e. Thus, the spatial orientation (R or S) of the 9-hydroxy function plays a significant but not a crucial role for irritant activity. Both epimeric (9 R)/(9 S)-hexadecanoates 2f/3j were non-irritant.