Volume 43, Issue 10

The reaction of [Cp 2 TiCl 2 ] with E(SiMe 3 ) 2 leads to dinuclear Ti complexes. In [Cp 3 Ti 2 S 2 Cl] (1) and [Cp 3 Ti 2 Se 2 Cl] (3) two μ 2 -S(Se) ligands bridge the Cp 2 Ti and CpTiCl units, respectively in contrast to these, [Cp 4 Ti 2 S 2 Cl 2 ] (2) contains a μ 2 η 1 -S 2 bridge connecting two Cp 2 TiCl fragments. A similar reaction of [CpTiCl 3 ] with Se(SiMe 3 ) 2 leads to the tetranuclear cluster [Cp 4 Ti 4 Se 7 O] (4). 4 consists of a Ti 4 -tetrahedron which encloses an oxygen atom.

PPh 3 Au(tolN 5 tol) is obtained by the reaction of PPh 3 Au + ClO 4 - with Tl(tolN 5 tol). It crystallizes in the monoclinic space group P2 1 /c with the lattice parameters a = 1548.8(5), b = 1070.7(2), c = 1779.1(3) pm, β = 90.33(2)°, Z = 4. In the monomeric complex the gold atom is nearly linearcoordinated by the phosphorus atom of the PPh 3 group and nitrogen atom N3 of the pentaazadienido ligand ( N3 - Au - P 178.4°). tolNN(NCH 3 )NNtol crystallizes in the orthorhombic space group Pccn with the lattice constants a = 2426.7(9), b = 469.3(2), c = 1195.3(4) pm. The unit cell contains four molecules, located on twofold axes. Due to the isolobality of the CH 3 and the PPh 3 Au group, the two structures are closely related. Both contain the typical planar zig-zag chain of five nitrogen atoms with located double bonds N1-N2 and N4 - N5 (from 119.8 to 126.6 pm) and shortened single bonds N2 - N3 and N3 - N4 (132.7 to 140.0 pm).

The tetrahalogenometallates CaHgBr 4 ·8H 2 O, CaCdI 4 ·8H 2 O and SrCdI 4 ·8H 2 O which have been obtained by crystallization from aqueous solutions form different structures. The orthorhombic compounds CaHgBr 4 ·8H 2 O (Cmca, a = 1720.1(6) pm, b = 1329.2(4) pm. c = 1369.5(7) pm, Z = 8, R =0.041) and SrCdI 4 ·8H 2 O (Pnma, a = 1404.6(2) pm, b = 1841.1(5) pm. c = 1420.6(3) pm, Z = 8, R = 0.037) are built up from dodecahedral [A(H 2 O) 8 ] cations (A = Ca, Sr) and tetrahedral MX 4 anions (M = Hg, Cd) which are cubic closed packed in a CuAu type structure. The tetragonal structure of CaCdI 4 ·8H 2 O (P4/nbm, a = 1268.14(13) pm, c = 536.96(35) pm. Z = 2, R = 0.034) contains antiprismatic [Ca(H 2 O) 8 ] 2+ cations and tetrahedral Cdl 4 anions, which form together a tetragonal primitive rod package.

The cyclothiazeno complex [Na-15-crown-5][MoF 2 Cl 2 (N 3 S 2 )] has been prepared by the reaction of sodium fluoride with [MoCl 3 (N 3 S 2 )] 2 in acetonitrile solution in the presence of [15-crown-5]. The compound was characterized by its IR spectrum as well as by an X-ray structure determination (3560 observed independent reflexions, R = 0.039). Crystal data: monoclinic, P2 1 /n, Z = 4; a = 1044.8(2); b = 1513.7(2); c = 1363.8(3) pm; β = 104.33(2)°. The structure consists of ion pairs, in which the sodium atom is seven-coordinated by the oxygen atoms of the crown ether molecule and by the two fluorine ligands of the [MoF 2 Cl 2 (N 3 S 2 )] - unit. The molybdenum atom is a member of the planar MoN 3 S 2 ring; the fluorine atoms are coordinated in trans position to the nitrogen atoms of the cyclothiazeno ring.

The structurally different radical anions M ⊖ of peralkylated 1-sila-2,5-diazacyclopentane-3,4-dithione and of tetrakis(isopropylthio)-p-benzoquinone are generated by reduction with potassium/2.2.2-cryptand under aprotic conditions in THF solution. On addition of Li ⊕ B(C 6 H 5 ) 4 ⊖ , both form hitherto elusive sulfur-containing contact ion pairs, which are characterized by their ESR/ENDOR spectra.

For the first time, 107,109 Ag ENDOR measurements in solution are reported. In addition, the formation of the known paramagnetic contact ion pair [Ag ⊕ (PR3) 2 (R 2 H 2 C 6 O 2 ·⊖ ] on reduction of 3,5-di(tert-butyl)-o-benzoquinone in THF solution containing soluble silver salts and triphenylphosphine is studied by cyclic voltammetry.

The crystal structure of Ca 5 Ga 2 N 4 (orthorhombic, space group Cmca, a = 487.3(2) pm, b =1110.5(3) pm, c = 1421.7(4) pm, Z = 4) contains infinite zig-zag chains of Ga atoms, which are in a tetrahedral coordination by two additional nitrogen atoms in terminal positions.

Mononuclear cobalt(o) complexes containing olefin and trimethylphosphane ligands Co(olefin)(PMe 3 ) 3 (olefin = C 2 H 4 (1), C 3 H 6 (2), cyclopentene (3), trans-1,2-diphenylethene (4), tetrafluorobenzo-bicyclo-(2.2.2)-octadiene (5)), are obtained from CoCl 2 by reaction with magnesium in the presence of the ligands or by substitution of 3 with olefin. X-ray crystal structure determinations of 4 and 5 show a distorted tetrahedral arrangement of ligands around the cobalt atom. Chemical and spectroscopic properties are consistent with a paramagnetic valence state of the compounds in solution. By reaction with carbon monoxide a dicobalt complex is formed, while azobenzene gives paramagnetic Co(N 2 Ph 2 )(PMe 3 ) 2 .

The preparations of the title compounds are reported. The species have been characterized by multinuclear ( 1 H, 13 C, 19 F, 31 P) NMR techniques. Their decomposition, leading mainly to PH 2 F 2 + MF6 - , was also studied. The Raman spectrum of CF 3 SPH 2 F + AsF 6 - is presented.

The bi- to quadridentate 1,3-dioxolane and 1,4-dioxane phosphane ligands Ph n P(CH 2 C 3 H 5 O 2 ) 3-n (1, 2). PhP(CH 2 C 4 H 7 O 2 ) 2 (3), and [-CH 2 P(Ph)CH 2 C 4 H 7 O 2 ] 2 (4) have been investigated with regard to their efficiency in the carbonylation of methanol to acetic acid using cobalt as a component of the catalyst. While 1, 2 are unstable towards acetic hydrolysis. 3 and 4 lead to methanol conversions of >95%, and selectivities to methyl acetate and acetic acid of 33%, and 60%, respectively.

Cp 2 ZrCl 2 reacts with an excess of PH 2 Ph in the presence of magnesium turnings to yield (Cp = η 5 -C 5 H 5 ) (1). Only the meso form of 1 is present in solution as well as in the solid state [with R or S configuration of P(1), S or R of P(3)]. 1 crystallizes monoclinicly in the space group P2 1 /c (Nr. 14) with Z = 4, a = 10.699(3), b = 15.065(3), c = 16.135(13) Å, β = 109.53(5)°. The structure was refined to R = 0.066 for 2082 reflections. The coordination of the P 3 Ph 3 2- ligand to the Cp 2 Zr fragment is nearly symmetrical (Zr-P: 2.635(2) and 2.622(2) Å), and the ZrP 3 metallacycle is almost planar.

The first antimony-sulfur-nitrogen heterocycle, t BuSb(NSN) 2 Sb t Bu (1b)**, has been prepared from the reaction of t BuSbCl 2 with the salt K 2 SN 2 . It forms stable chelate complexes of the type (CO) 4 M[ t BuSb(NSN) 2 Sb t Bu] (M = Cr (3b), Mo (4b), W (5b)). The pentacarbonylchromium complex (CO) 5 Cr[ t BuSbCl 2 ] reacts with K 2 SN 2 to give the mononuclear derivative (CO) 5 Cr[ t BuSb(NSN) 2 Sb t Bu] (2b) containing the eight-membered ring 1b, whereas the corre-sponding complexes (CO) 5 Cr[R 2 SbCl] (R = t Bu, Ph) are converted into binuclear sulfur diimide derivatives (CO) 5 Cr[R 2 Sb(NSN)SbR 2 ]Cr(CO) 5 (R = t Bu (6b). Ph (7b)). The new stibino-sulfur diimides 1b-7b have been characterized by IR and NMR ( 1 H and 13 C) spectroscopy.

Triphenylmethylphosphonium nitrite and formate have been prepared by the reaction of [PPh 3 Me]I with silver nitrite, and lead formate, respectively, in aqueous solutions. [PPh 3 Me]NO 2 (1) forms pale yellow crystals, and [PPh 3 Me]HCO 2 ·H 2 O (2) forms white crystals. Both compounds are soluble in water, ethanol, and dichloromethane. In moist air 2 is hydrated to yield [PPh 3 Me]HCO 2 ·2H 2 O (3). The compounds were characterized by their IR spectra, 1 and 2 also by X-ray crystal structure determinations. [PPh 3 Me]NO 2 (1): space group P2 1 /n, Z = 4, 2088 independent observed reflexions, R = 0.062. Lattice dimensions (20 °C): a = 914.7(3), b = 1887.5(9), c = 1080.0(4) pm, β = 110.29(3)°. The compound consists of PPh 3 Me + ions and NO 2- anions with bond lengths of 114.2(6) pm and a bond angle of 124.1(7)°. [PPh 3 Me]HCO 2 ·H 2 O (2): space group P2 1 /n, Z = 4, 2973 independent observed reflexions, R = 0.069. Lattice dimensions (-20 °C): a = 931(2), b = 1558(3), c = 1281(2) pm, β = 105.9(1)°. The compound consists of PPh 3 Me + ions and formate anions which form centrosymmetric dimeric units [HCO 2 ·H 2 O] 2 2- through hydrogen bridges of the water molecules. Bond lengths CO 122.4(4) and 120.9(4) pm. bond angle OCO 129.9(4)°.

Chloro bis(trimethylsilyl)methylene phosphane (4) reacts with the diazo compounds 5, 10, 15 and 20 even at low temperatures with formation of the 3H-1,2,4-diazaphospholes 6,11,16 and 21. The products are unstable and decompose either with elimination of nitrogen to yield 1-chloro phosphiranes (9,14, 19 and 22), or isomerize with aromatization (11 → 13) or transformation into 4,5-dihydro-1,2,4-diazaphospholes (6 → 8, 16 → 18) by trimethylsilyl shifts. Silyl groups attached to ring nitrogen are easily hydrolized (8 → 7,13 → 12, 18 → 17), those attached to ring carbon are cleaved by treatment with potassium fluoride in dimethyl formamide (7 → 23, 12 → 24).

We report first the complete study of the reactions of [CpMo(CO) 2 ] 2 (Mo≡Mo) (1, Cp = η 5 -C 5 H 5 ) with salt-free phosphorus ylides Ph 3 P=CHR (2, Ph = C 6 H 5 ; R = H (2a), CH 3 (2b), C 3 H 7 (2c), C 6 H 5 (2d)) and with the Nal-adducts of the ylides Ph 3 P=CMe 2 (Me = CH 3 ), PhMe 2 P=CH 2 and (PhO) 3 P=CH 2 . With 2, products of the type Cp(CO) 2 LMo-MoL(CO) 2 Cp (7, L = ylide) were obtained, and the salt adducts gave addition compounds of the type Cp(CO) 2 LMo-MoL(CO) 2 Cp-2NaI (12, L = ylide). These very reactive products represent novel bisphosphonioalkyl complexes, and were characterized by IR, mass and 1 H NMR spectrometry. The reaction of 1 with hexaphenylcarbodiphosphorane, C(PPh 3 ) 2 , leads to a novel double addition product, Cp 2 Mo 2 (CO) 4 [C(PPh 3 ) 2 ] 2 (14). Some reactions of compounds 7, 12 and 14 were also studied; 7d (L = CHPh -PPh 3 ) reacts with NaNH 2 yielding ammonia and the disodium salt of the novel dianionic complex [CpMo(CO) 2 (CPh-PPh 3 )] 2 2- (15); 7a (L = CH 2 -PPh 3 ) reacts with CH 3 I forming CpMo(CO) 3 CH 3 and traces of CpMo(CO) 2 (PPh 3 )I; all compounds of types 7,12 and 14 react with adsorbents (Silica-gel, Al 2 O 3 , etc.); thus chromatography is impossible, even under strict protection from air and humidity. A study of the processes occurring during chromatography under various conditions and the resulting products are also reported and discussed. [CpW(CO) 3 ] 2 (18) reacts with 2a forming also a bisphosphonioalkyl complex [CpW(CO) 2 L] 2 (L = CH 2 =PPh 3 ); in this case, the ylide substitutes two carbonyl groups in 18. The compounds [Cp*M(CO) 2 ] 2 (M≡M) (Cp* = C 5 Me 5 ; M = Cr, W) apparently do not react with phosphorous ylides; the corresponding Mo compound, [Cp*Mo(CO) 2 ] 2 , does react, but only the new mono-nuclear complex Cp*Mo(CO) 2 (PPh 3 )Cl (22) could be isolated.

Mild thermolysis of cationic tungsta-phospha-bicyclo[1.1.0]butanone complexes yields novel η 2 -phosphinocarbene complexes.

The crystal structures of three isotypic hexacyanometallates(III) (NMe 4 ) 2 LiM(CN) 6 ·2H 2 O have been determined and refined in the monoclinic space group C2/c, Z = 4, to wR = 0.053 (M = Mn, 959 independent single crystal reflections), 0.041 (M =Fe, 2002 reflections) and 0.037 (M = Co, 1881 reflections). The stucture is elpasolite-related by its face-centered pseudocubic arrangement of M atoms within nearly undistorted M(CN) 6 3- octahedra, six of which form strongly distorted octahedral N 6 cavities occupied by dihydrated lithium ions. The resulting average distances for the M(CN) 6 3- octahedra are Mn-C = 201, Fe-C = 194.7, Co-C = 190.3, and C-N = 114 pm. The lithium coordination is distorted tetrahedral, consisting of LiO 2 N 2 units with distances of about Li-O = 194, Li -N = 209 pm (for M = Fe, Co). The remaining four N atoms of the N 6 cavity are bound by hydrogen bridges from the two aqua ligands, O-H···N = 283 and 295 pm. The relations to the hydrated elpasolite structure of (NMe 4 ) 2 NaFe(CN) 6 ·H 2 O are discussed.

The weak Brönsted acids B 6 H 7 - and XB 6 H 6 - , X = Cl, Br, I; pk a : 7-4,75, are formed by protonation of B 6 H 6 2- and XB 6 H 5 2- respectively. The deuteration rates, evaluated from integrated IR band intensities of the BH and BD stretching vibrations, are linearly dependent on the mole fractions of the protonated species, and decrease with increasing degree of halogenation in the series Cl>Br>I. H atoms trans-positioned to halogens are exchanged 100 times more rapidly than the remaining ones. The activation energy for the H/D exchange amounts to 76 ± 1,5 kJ/mol for B 6 H 7 - . The lower symmetry of the protonated borates is evident from additional IR and Raman bands. They are distinguished from the corresponding Brönsted bases by a high frequency shift of the BH stretching vibrations in the order of 100 cm -1 . Due to the pH dependent equilibrium B 6 H 6 2- /B 6 H 7 - and different solubilities of the tetrabutylammonium salts, the separation of B 6 H 6 2- /B 12 H 12 2- mixtures is achievable. In alkaline solutions the very soluble B 6 H 6 2- is present, whereas (TBA) 2 B 12 H 12 precipitates quantitatively. By subsequent cautious acidification of the supernatant, insoluble (TBA)B 6 H 7 is obtained.

Treatment of B 6 H 6 2- with iodoalkanes and (SCN) 2 in organic solvents affords the monosubstituted protonated hexaborates RB 6 H 6 - , R = CH 3 , C 2 H 5 < C 3 H 7 , C 4 H 9 , C 8 H 17 and SCN, respectively. The acidity constants of these weak Brönsted acids range for the alkylated species from 8.8 to 9.6, and for R = SCN the pk a value is ~5. From basic solutions the salts Cs 2 RB 6 H 5 can be precipitated, which show band patterns in the IR and Raman spectra typical for monosubstituted hydrohexaborates. The protonated compounds RB 6 H 6 - are distinguished from the corresponding Brönsted bases RB 6 H 5 2- by a high frequency shift of the BH stretching vibrations in the order of 100 cm -1 . For Cs 2 (SCN)B 6 H 5 , S coordination of SCN - is supposed because of the high frequency of ν CN : 2144 cm -1 .

The reaction of 2-aryl-2H-isoindoles with trifluoroacetic anhydride in pyridine leads to the formation of the corresponding 1-trifluoroacetyl-2-aryl-2H-isoindoles with acceptable yields. 1-Alkylthio-2-aryl-2H-isoindoles can be generated from 3-alkylthio-2-aryl-1 H-isoindolium-tri-fluoromethanesulfonates with pyridine and acylated in the same manner. Protonation occurs at 1-position and yields isolable 1H-isoindolium salts.

The complete primary structure of the two hemoglobin components of the adult North Persian Leopard are presented. The major component Hb-I accounts for 80-90% and the minor component Hb-II accounts for 20-10% of the total hemoglobin. Reversed phase HPLC was used for the separation of the polypeptide chains. The amino acid sequences were established by automated Edman degradation of the globin chains and of the tryptic peptides in liquid-and gas-phase sequenators. The sequences are aligned with those of human Hb-A. Our result shows that the hemoglobins of North Persian Leopard and Jaguar are identical in amino acid sequence.

From the ethyl acetate fraction of methanolic extract of red alga, L.pinnatifida, a new halogenated sesquiterpene named as pinnatifidone [1] has been isolated and the structure of this compound has been elucidated with the help of intensive spectroscopic studies.

A variety of pyridines was prepared from reaction of N-benzylidenecyanoethanoic hydrazide (2) with malononitrile, benzoylacetonitrile, cyanoacetamide and cinnamonitrile derivatives. The reactivity of 2 towards a variety of ketones was studied.

Several hydrolytic enzymes (porcine liver esterase, lipase from wheat germ type I, and the lipase from rhizopus javanicus) efficiently deacetylate laevoglucosane triacetate (2) with good regioselectivity into diacetylated laevoglucosane derivatives (3-5).

2-Amino-5-nitro-6-ribitylamino-4(3H)-pyrimidinone (7) was phosphorylated with chlorophosphoric acid yielding an isomer mixture containing about 63% of the 5´-phosphate 7a together with other monophosphates and bisphosphates of 7. Preparative HPLC afforded pure 7a. Catalytic hydrogenation of 7a yields the labile substrate of pyrimidine deaminase, 2,5-diamino-6-ribityl-amino-4(3H)-pyrimidinone 5´-phosphate (2a). The product of the enzyme, 5-amino-6-ribityl-amino-2,4(1H,3H)-pyrimidinedione 5´-phosphate (4a), can be obtained from 5-nitro-6-ribityl-amino-2,4(1H,3H)-pyrimidinedione (8) by an analogous procedure. The 3´-and 4´-monophos-phates of 2,5-diamino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione are not substrates for the deaminase. 5´-Phosphates of a variety of ribityl-substituted pyrimidines and pteridines could also be obtained by phosphorylation with chlorophosphoric acid without the use of protecting groups.

The 57 Fe Mössbauer quadrupole splittings of FeSiF 6 ·6H 2 O (known to contain [Fe(H 2 O) 6 2+ ) and fast frozen aqueous solutions of Fe(II) are different. We propose an explanation in terms of the dimerization of Fe(II) in aqueous solution via an H 3 O 2- ,H 5 O 2 + double bridge.

Mesogenic 1,16-di-(1 -O - D-mannityl)-hexadeca-ne (8), 1,22-di-(1-O-D-mannityl)-docosane (9), 1-(1-O - D-mannityl)-hexadecane-16-ol (10) and 1-(1-0 - D-mannityl)-docosane-22-ol (11) are prepared from the respective α,ω-diols by glycosylation followed by glycoside reduction and deprotection.