Volume 45, Issue 11

CdCl 2 dissociates in dimethylformamide into the species Cd(DMF) 6 2+ , CdCl(DMF) 5 + and CdCl 3 - as determined by 113 Cd NMR spectroscopy. 11 B and 113 Cd NMR spectra of MBH 4 /CdCl 2 solutions in this solvent show the presence of complexes [CdCl 2 -n (BH 4 ) n+1 ] - with rapid exchange of BH 4 - and Cl - at ambient temperature. There is no evidence that Cd(BH 4 ) 2 is formed in a metathetical reaction. The crystal structure of CdCl 2 · 2 DMF has been determined. It is a coordination polymer containing hexacoordinated Cd atoms with the DMF molecules in cis-position. Coordination of DMF occurs via the carbonyl oxygen atoms.

CdI 2 dissociates in dimethylformamide (DMF) into Cd(DMF) 6 2+ , CdI(DMF) 5 + , CdI 3 - and CdI 4 2- . Rapid scrambling occurs at ambient temperature in DMF solutions containing CdI 2 and MBH 4 (M = Na, Li). At 213 K these exchange processes are slowed down to allow the detection of CdI 4 2- , CdI 3 - , CdI 3 (BH 4 ) 2 -, CdI 2 (BH 4 ) 2 2 -, CdI(BH 4 ) 3 2 -, CdI(BH 4 ) 2 - and Cd(BH 4 ) 3 - by 113 Cd NMR spectroscopy. The BH 4 groups are bound to the Cd centre via two hydrogen atoms as derived from the multiplicity of the 113 Cd signals. CdI 2 dissolves in diglyme as a molecular entity. Its reaction with M BH 4 proceeds via solvated CdI(BH 4 ) and Cd(BH 4 ) 2 to CdI(BH 4 ) 3 2 - and Cd(BH 4 ) 3 - . Solubility restriction prevent a 113 Cd NMR study of solutions in which the MBH 4 : CdI 2 ratio exceeds 1:1.

Cadmium bis(tetrahydroborate) has been prepared from dimethyl cadmium and H 3 B · THF in tetrahydrofuran. Low temperature 113 Cd NMR spectra recorded for THF, monoglyme and diglyme solutions show a septet with 1 J( 113 Cd 1 H) = 273 Hz. This proves that the BH 4 ⁻ groups are bound to the metal centre via triple hydride bridges. Reaction of Cd(BH 4 ) 2 with LiBH 4 yields LiCd(BH 4 ) 3 quantitatively in diglyme solution.

Reaction of 1,1,3,3-tetrakis(dimethylamino)-lλ 5 ,3λ 5 -diphosphete (1) with perfluorobenzonitrile yields 1,1,3,3-tetrakis(dimethylamino)-4-(4-cyano-2,3,5,6-tetrafluorophenyl)-1 -fluoro-1λ 5 ,3λ 5 -diphosphabuta-1,3-diene (3); reaction of 1 with benzoisonitrile gives 2,2,4,4-tetrakis(dimethylamino)-1-isocyano-1-phenyl-2λ 5 ,4λ 5 -diphosphapenta-1,3-diene (4). The new products 3 and 4 are characterized by their NMR, mass, and IR spectra. The mechanism of formation is discussed. The structure of 3 was elucidated by an X-ray structural analysis.

Ruthenium thiolates [cpRu(PR′ 3 ) 2 (SR)] (PR′ 3 = PPh 3 ,1/2 dppe, 1/2 dppm, R = Me, CH 2 Ph) are obtained from the corresponding chlorides and NaSR. PPh 3 is readily exchanged for CO to give the chiral complexes [cpRu(PPh 3 )(CO)(SR)]. Alkylation with methyl tosylate yields the cations [cpRu(dppe)(SMeR)] + and [cpRu(PPh 3 )(CO)(SMeR)] + , which were isolated as their PF 6 - salts. The neutral carbonyls add dimethyl acetylenedicarboxylate giving five-membered metallocycles.

Colorless orthorhombic single crystals of Be[C 2 (COO)2] · 4 H 2 O were grown in aqueous silica gel. Space group Cmcm, α = 1004.7(1), b = 675.0(1), c = 1262.4(2) pm, R g = 0.0264. The crystal structure consists of Be(H 2 O) 4 2+ tetrahedra and planar [C 2 (COO) 2 ] 2- anions linked together by strong asymmetric hydrogen bonds. A layer-like arrangement extending parallel (010) made up by [C 2 (COO) 2 ] 2- anions and hydrogen bound water molecules of the Be(H 2 O) 4 2+ tetrahedra is the primary structural feature of Be[C 2 (COO) 2 ] · 4H 2 O. These layers are stacked and interlinked by coordinative bonds between Be 2+ and H 2 O to yield a rigid three-dimensional framework. Thermal decomposition commences with endothermic loss of water of crystallisation at 160 °C followed by several steps of exothermic degradation yielding finally a soot-like amorphous residue.

The missing tellurium member of the 1,2,3-trichalcogena-[3]ferrocenophanes, Fe(C 5 H 4 Te) 2 Te, was synthesized and structurally characterized. The shiny needles are composed of alternating layers of tellurium and parallel ferrocene units. The molecules Fe(C 5 H 4 Te) 2 Te contain eclipsed cyclopentadienyl rings which are connected by a Te 3 bridge.

The ammonium salts of the complex anions trans-diiodobis(ethanedial-dioximato)-cobaltate(III), [Col 2 (GH) 2 ] - , and trans-diiodobis(ethanedial-dioximato)rhodate(III), [RhI 2 (GH)2] - (GH - = ethanedial dioximate or glyoximate), have been synthesized and their structures determined from single crystal X-ray diffraction data at room temperature. The crystals of the two salts are monoclinic, space group C2/c. NH 4 [CoI 2 (GH) 2 ] (I) crystallizes as dark-brown prisms with a greenish reflectance; its crystal data are: C 4 H 10 Col 2 N 5 O 4 , M r = 504.90; a = 8.910(6), b = 11.700(9), c = 11.691(6) Å; β = 93.55(5)°; V = 1216.4 Å 3 ; Z = 4; D c = 2.78 Mg m -3 . NH 4 [RhI 2 (GH) 2 ] (II) crystallizes as yellow-brown blocks with crystal data: C 4 H 10 I 2 N 5 O 4 Rh, M r = 548.88; a = 9.038(4), b = 11.949(5), c = 11.770(3) Å; β = 95.54(3)°; V = 1265.16 A 3 ; Z = 4; D c = 2.87 Mg m -3 . The two structures were refined to a final R W = 0.045 for 1209 observed independent reflections and 95 parameters for I, and to a final R W = 0.040 for 1922 observed independent reflections and 87 parameters for II. The coordination geometry around Co or Rh in the anionic complexes is a distorted (4 + 2) octahedron of four equatorial chelating N atoms and two apical iodides. The H atoms of the hydroxyl groups are involved, as usual, in intramolecular O—H—O bridges with uniform Ο···Ο separations of 2.582 Å for I, and 2.713 Å for II. The rectilinear I—Co—I or I—Rh—I triads form “infinite” zigzag chains extending parallel to the ab plane, with a weak I—I contact of 3.988 Å for I, and 4.010 Å for II.

The metalation of 2,4,6-tri-tert-butylamino-tert-butylfluoromethylsilane (1) with butyllithium leads to the formation of the LiF adduct of the iminosilane 2. In 2 the silicon atom is pentavalent and four-coordinated. The corresponding sodium compound is the fluorosilylamide 3. The nitrogen has a planar environment in 3.

a-P 9 Et 5 (1) and a-P 9 (i-Pr) 5 (2) have been obtained by reacting a mixture of (PEt) 5 and PC1 3 and of i-PrPCl 2 and P 4 , respectively, with magnesium. Compound 1 has been isolated in 95% purity, whereas 2 has been highly enriched in the product mixture. According to their 31 P{ 1 H}-NMR spectra, 1 and 2 are 2,4,6,8,9-pentaorganyltricyclo[3.3.1.0 3.7 ]nonaphosphanes (a-P 9 R 5 ) containing a P 9 skeleton analogous to that of noradamantane. In addition, small portions of another constitutional isomer with a structure analogous to that of brexane (b-P 9 R 5 ) have been detected.

The formation of FeCr 2 O 4 from Fe, Fe 2 O 3 and Cr 2 O 3 in vacuum at 800°C has been investigated by X-ray diffraction and Mössbauer spectroscopy. The reaction mechanism is supposed to include a complicated redox reaction forming the intermediate ferrous components magnetite and wüstite, and then a diffusion reaction between wüstite and gas-transported Cr 2 O 3 forming FeCr 2 O 4 .

The synthesis of tri(phenylethynyl)arsane (1) and -stibane (7) is discussed. Octacarbonyldicobalt reacts selectively with 1 or 7 to yield the η 2 -side-on co-ordinated phenylethynyl complexes (Ph–C=C) n E[(η 2 -C≡C–Ph)Co 2 (CO) 6 ] 3-n (E = As: n = 2: 3, n = 1: 4, n = 0: 5; E = Sb: n = 2: 8; n = 1: 9; n = 0: 10), which contain sterically hindered carbon-cobalt tetrahedrane cluster units. 3 gives upon heating {(Ph–C≡C) 2 As[(η 2 -C=C–Ph)Co 2 (CO) 5 ]} 2 (6) a compound containing a six-membered Co 2 As 2 C 2 ring. All new compounds have been characterized by analytical and spectroscopic data (IR, 1 H, 13 C NMR), and (Ph –C≡C)As[(η 2 -C≡C–Ph)Co 2 (CO) 6 ] 2 (4) by X-ray analysis.

[CuSC 6 H 2 (i-Pr) 3 ] n = 4 (1), and n = 8 (2) are obtained from CuCO 3 · Cu(OH) 2 and 2,4,6-tri(isopropyl)thiophenol in a slow reaction, where long reaction times promote the formation of octameric 2.1 crystallizes as colorless platelets, space group C 2/c: a = 3647(2), b = 854.8(6), c = 2061.3(7) pm, β = 105.98(4)°, Ζ = 4. Central unit of the tetrameric complex with the symmetry C 2 is a non planar eight-membered Cu–S heterocycle. The four Cu atoms form a rhombus with short edges of 269.7 and 270.1 pm. The bridging SR-ligands are arranged alternatingly above and below the Cu 4 rhombus. Octameric 2 crystallies as 2•(H 2 O) x in the form of orthorhombic yellow blocks, space group Pbcn: a = 2513(1), b = 1975(1), c = 2747(1) pm, Z = 4. The thiolato ligands connect the Cu atoms to form a folded 16-membered Cu–S ring with the symmetry C 2 . The eight S atoms are arranged at the corners of a cube with the Cu atoms occupying eight of its edges. The Cu–Cu distances are in the range of 267.8 to 304.0 pm. In 1 as well as in 2 the Cu atoms are linearly coordinated with Cu–S distances of 214.7 to 217.9 pm.

The crystal structure of the spinel type fast ionic conductor Li 2 MnCl 4 is redetermined by single crystal X-ray diffraction with respect to both cation distribution and Frenkel disorder. The final R value for 166 unique reflections is 0.029 (space group Fd3m, structural parameter u = 0.25623(3), a = 1050.27(5) pm). Contrary to the results based on neutron powder data (van Loon and de Jong, 1975) Li 2 MnCl 4 is fully inverse. The thermal ellipsoids of the ions involved are discussed in terms of the lattice vibrations of the spinel structure and the mobility of the lithium ions.

Square-planar rhodium(I) complexes [RhCl(iPr 2 PC 2 H 4 Y) 2 ] (8, 9) containing one chelating and one P-bonded monodentate phosphine ligand are prepared from [RhCl(C 8 H 14 ) 2 ] 2 (7) and the new functionalized phosphines iPr 2 PC 2 H 4 Y (5,6). Reaction of 9 (Y = NMe 2 ) with CO and of 8 (Y = OMe) with CO, C 2 H 4 , C 2 H 2 , C 2 Ph 2 and HC 2 Ph leads to opening of the chelate ring and formation of the complexes trans-[RhCl(L)(η 1 -P–iPr 2 PC 2 H 4 Y) 2 ] (10-15). Treatment of 8 with H 2 gives the dihydridorhodium(III) compound [RhH 2 Cl(iPr 2 PC 2 H 4 OMe) 2 ] (16). The vinylidene complexes trans-[RhCl(=C=CHR)(η 1 -P– iPr 2 PC 2 H 4 OMe) 2 ] (17, 18) are obtained by thermal or pyridine promoted rearrangement of 13 (L = C 2 H 2 ) and 15 (L = HC 2 Ph). 13 and 15 have also been used as starting materials for the synthesis of the cyclopentadienyl alkyne and vinylidene complexes 19-21. The X-ray crystal structure of the parent compound 8 was determined.

The reactions of isopropyl indium dichloride (1) with LiN(H)t-Bu and of mesityl indium chloride (2) with NaN(SiMe 3 ) 2 lead to compounds [i-Pr(Cl)InN(H)t-Bu] 2 (3) and [Mes(Cl)InN(SiMe 3 ) 2 ] 2 (4), respectively. 3 forms dimers in solution and in the solid state, while the monomer is the predominate species of 4 in solution. 3 crystallizes in 2 isomers. The X-ray analysis of one isomer of 3 is reported.

Eleven analogs of the luteinizing hormone-releasing hormone (LHRH) have been designed, synthesized, bioassayed and compared for antiovulatory activity (AOA) in rats. The emphasis of design was on analogs with D–Ala 10 , Sar 10 , D–Ser 10 , (desGly 10 , NHEt), D–Abu 10 , Gly 10 , and with substitutions in position 5, 6, and 8. High antiovulatory activity was obtained with analogs having D– Ala in position 10. Four earlier analogs, 1, 4, 11 and 13, with D– Ala in position 10, showed 67-100% AOA at 0.25 μg in rats. Analog 1 showed 60% AOA at 0.125 μg. The replacement of D–Ala 10 in analog 11 by Sar 10 in analog 12, retained activity, 62% vs. 67% AOA at 0.25μg, 100% vs. 90% AOA at 0.5 μg. This analog with Sar 10 was the only one that did not show substantial loss of activity upon replacement of D–Ala 10 .

Research on the chemical composition of gorgonian Pseudoterogorgia americana, which grows in the coasts of Havana, has led to the isolation of a new sesquiterpene hydrocarbon, 1,1-dimethyl-7-isopropylidene-1,2,3,4,5,6,7,8-octahydronaphthalene, named caridiene. This compound not previously reported, was found to be a major constituent of the volatile fraction. The proposed structure was confirmed by spectroscopical data (UV, IR, Raman, MS, 1 H and 13 C NMR techniques).

Reaction of 1-benzothiepine (4), whose synthesis has been improved, with trimethyloxonium tetrafluoroborate yields 1-methyl-1-benzothiepinium tetrafluoroborate (5). Compound 5 rearranges to methyl 1-naphthyl sulfide (6) on heating in acetonitrile. The reaction rate 5 → 6 was determined at one temperature (75°C).

X-ray analysis of the reaction product — dibenzo[c,f]oxocane derivative — between benzocyclopropene and diphenylcyclopropenones.

Treatment of organic thiocyanates with aluminium oxide, at room temperature, is found to afford a convenient procedure for the synthesis of symmetric disulphides, under mild conditions. An X-ray structure analysis of meso-di-(1,6-methano[10]annulen-2-yl)-disulphide (2a) suggests an intermediate sp 2 —-sp 3 hybridization state for the aromatic carbon atoms and a faceasymmetric electronic distribution in the annulene ring. Using reported atomic coordinates, a similar configuration is determined for the parent structure 7. A higher π-electron density on the exo face of the aromatic ring may account for the known syn,syn stereochemical course of electrophilic addition to 7, as well as for the high reactivity of this system towards electrophiles, in addition and in substitution reactions.

The structural intactness of many biopolymers in mummified tissues is well documented. By way of contrast no functional evidence of an isolated protein is known. The well defined air dried mummy of a deceased 16±2 year male teenager 1200 B. C. prompted us to search for the possible presence and function of Cu 2 Zn 2 superoxide dismutase or remnants thereof. Using two different assay systems unequivocal proof of a specific Cu 2 Zn,superoxide dismutase activity in brain extract was demonstrated. Fast protein liquid chromatography of the extract on Superose 12 revealed an approx. 5 kD Cu-containing polypeptide to which activity was assigned. It is assumed that during the ageing process considerable portions of the 31.3 kD homodimer were cleaved leaving this active core up to the present date. This would be the first case of the presence of an enzymically active component surviving the past 3000 years of mummification.

The title compound has been prepared by the reaction of CuCl, with hexakis(trimethylsilyl)-benzdiamidine, in boiling acetonitrile in the presence of traces of water, as brown crystals, which were characterized by their IR spectrum as well as by an X-ray structure determination. Space group C 2/c, Z = 4, 2668 observed unique reflexions, R = 0.036. Lattice dimensions at –65 C: a = 879.5(2), b = 2441.1(3), c = 1241.4(3) pm, β = 95.24(3)°. In the structure four copper atoms surround an oxygen atom in a slightly distorted tetrahedral fashion; the chlorine atoms bridge adjacent copper atoms, and each copper atom is thus bound to three chlorine atoms. The nitrogen atoms of the acetonitrile complete the slightly distorted trigonal bipyramid around the copper atoms.

Hydroboration, 3,3-Dimethyl-(e)-1-chlorodimethylsilyl-1-chloro-dimethylaminoboryl-butene-1,1,3-Bis(dimethylamino-2,2,5,5-tetramethyl-4,6-bis-(t-butylethylene)-1,3-dibora-2,5-disilacyclohexane Hydroboration of chlorodimethyl(3.3-dimethylbutynyl)silane with HBCl 2 /BCl 3 yields 3.3-dimethyl-(e)-1-chlorodimethylsilyl-1-dichloroboryl)-butene-1 (1 a), in which a chlorine atom at the boron can be substituted using Me 3 SiNMe, to give the corresponding chlorodimethylaminoboryl derivative 1 b. Dehalogenation of 1 b with Na/K alloy does not lead to the three-membered ring compound 2, but surprisingly yields the 1,3-dibora-disilacyclohexane derivative 3. The X-ray structure analysis shows a six-membered ring with a chair conformation, a small angle B 1–Si 2–B 1′ = 95.4(1)°, and long Si–B bonds (2.038 Å).

Cp*TaF 4 (1) (Cp* = η 5 -C 5 Me 5 ) forms a Lewis acid Lewis base adduct with the iminophosphorane HN = PPh 3 (2). The adduct Cp*TaF 4 ·NH=PPh 3 (3) is remarkably stable to thermal decomposition. The X-ray crystal structure of 3 was investigated.

A new pentaoxigenated xanthone has been isolated from aerial parts of the fern Cystopteris fragilis. By spectroscopic and chemical methods this compound has been shown to be 1,6-dihydroxy-3,5,7-trimethoxyxanthone which is of biosynthetic interest in ferns.