Volume 39, Issue 1

The following salts of the 1,2-hydrazine-bis(dithiocarboxylic acid) have been prepared: M 2 [S 2 CNH -NHCS 2 ], M = Na, K and M 3 [S 2 CN-NHCS 2 ], M = Na, K. In the solvated crystals K 2 [S 2 CNH-NHCS 2 ] · 4 CH 3 OH (a = 718.0(5), b = 1329.3(8), c = 937.7(9) pm, β = 109.26(6)°, space group C2/m, Z = 2) the [S 2 CNH-NHCS 2 ] 2- ion possesses crystallographic C 2h symmetry, i.e. a trans planar structure with a N-N bond length of 139.2(3) pm. Vibrational spectra indicate a lower symmetrical anion in the unsolvated crystals. In the trianion [S 2 CN-NHCS 2 ] 3- the C-N stretching vibrations are observed at 1400 and 1310 cm -1 .

Pure isomers of X n B 10 H 10-n 2- ; X = Cl, Br, I; n = 1, 2; are isolated by ion exchange chromatography on diethylaminoethylcellulose. Their structures are determined by 11 B and 11 B { 1 H }NMR spectroscopy. There are characteristic chemical shifts due to apical and equatorial substituents, respectively. The highest field signals are explained by the antipodal effect. In contrast to theoretical predictions the experimental investigations show, that the successive electrophilic substitution preferably occurs on equatorial and not on apical B atoms. IR and Ram an spectra of the 2-XB 10 H 9 2- species are very similar in the ν(BH) and in the B 10- cage absorption region. In the far infrared there are two characteristic bands, shifting to lower frequencies in the series Cl, Br, I, which are therefore assigned to (B 10 ) - X stretching and (B 10 ) - X deformation modes.

The P=S and P=0 derivatives 2a, b of diphenylphosphino N,N-dimethylthioformamide (1) were obtained by addition of sulfur to 1 and by Arbusov reaction of Ph 2 POMe with Me 2 NC(S)Cl, respectively. The position of the cis-P N-methyl proton signal is markedly affected by the P = X group which exerts a diamagnetic shift for X = S (2a) but a paramagnetic shift for X = O (2b) relative to 1. Unusually small 3 J PC couplings are observed in the 13 C{ 1 H} NMR spectrum. The P-sulfide 2 a crystallizes in the monoclinic space group C2/c with the lattice constants a = 1791.5(3) pm, b = 686.7(2) pm, c = 2591.3(4) pm, β = 93.10(4)°. The molecule structure is characterized by a planar thioamide unit with the P=S group forming an angle of 53.4° to the plane.

The hybrid phases Nb 59 O 147 F and Nb 65 O 161 F 3 were prepared at high temperature and investi­gated by high resolution transmission electron microscopy. Both phases have block structures. The sample of the phase Nb 59 O 147 F is very well ordered, whereas the phase Nb 65 O 161 F 3 shows some defects. In a sample of Nb 65 O 161 F 3 microdomains of a new 2:1 hybrid phase Nb 96 O 238 F 4 were found. Structural differences of the systems Nb 2 O 5 /NbO 2 F and Nb 2 O 5 /WO 3 are discussed.

The new compound Ba 5 (GaS 4 ) 2 crystallizes in the orthorhombic system (space group: Cmca) with lattice constants a = 2249.4(12) pm, b = 1214.6(8) pm, c = 1188.7(8) pm. In the structure there are isolated GaS 4 5- -tetrahedra. According to stoichiometry and structure this compound belongs to the complex salts, and is the first othiogallate(III).

The structure of [(t-BuP) 3 Cr(CO) 5 ], C 17 CrH 27 O 5 P 3 , has been determined by single crystal X-ray techniques, solved by ‘direct methods', and refined to R = 0.048, wR = 0.050 for 3657 reflections by blocked least squares. The compound crystallizes in the space group P 2 1 /c with a = 1664.9 pm, b = 916.5 pm , c = 3089.8 pm, β= 91.45° and Z = 8 formula units. The structure consists of two crystallographically independent but structurally nearly identical mononuclear [(t-BuP) 3 Cr(CO) 5 ] complexes with the three-membered ring (t-BuP) 3 as an unidentate σ-donor ligand. Compared to the free molecule (t-BuP) 3 the cyclophosphane ligand is slightly distorted on account of its coordination to the Cr(CO) 5 -group.

In dithiotropolone (2-mercaptocycloheptatrienethione) a novel type of S - H···S hydrogen bond is observed from spectroscopic results and from a single crystal X-ray structure analysis. Intramolecular S-H···S bonds with a very short S ··· S separation of 3.13 Å and with d(S···H) = 2.10 Å, ∢ (S-H···S) = 136° are formed, the S-H stretching frequency of 2450 cm -1 being lowered by about 120 cm -1 from the value for the free SH group. A different relationship between S···S bridge bond distances and S-H stretching frequencies applies as compared to the intermolecular bridges of thiophosphinic and thiocarbonic acids. Crystalline dithiotropolone is monoclinic, space group P2 1 /c, Z = 8, with a = 8.352(2), b = 13.806(4), c = 12.371(2) Å, β= 103.46(2)°.

1,3,4,5-Tetraethyl-2-methyl-1,3-diborolene (1) reacts with MX 2 (M = Pd, Pt) and Na(C 5 H 5 ) to give orange-red cyclopentadienyl(1,3-diborolenyl)palladium 3 and the yellow platinum complex 4, respectively. Bis(1,3,4,5-tetraethyl-2-methyl-1,3-diborolenyl)platinum (5) is obtained in low yield from 1, Na(HBEt 3 ) and PtCl 2 or from 1 and [(C 2 H 4 )PtCl 2 ] 2 . 1 H, 11 B, and 13 C NMR data of 3, 4, and 5 are in agreement with a sandwich structure. The 16e complex 5 is reduced by potassium to its mono- and dianion.

The thermal or photochemical reaction of [Cp(CO) 3 Fe]BF 4 with the isocyanides MeNC and tBuNC provides ready access to the salts [Cp(CO)(CNR) 2 Fe]BF 4 [R = Me (2a); tBu (2b)] and [Cp(CNR) 3 Fe]BF 4 [R = Me (3a); tBu (3b)]. Treatment of 2a, b and [Cp(CO) 2 (MeNC)Fe]BF 4 with two moles of Me 3 P=CFT leads to the formation of the ironacyl ylides Cp(RNC) 2 Fe- C(O) -CH=PMe 3 [R = tBu (4a); Me (4b)] and Cp(CO)(MeNC)FeC(O)CH = PMe 3 (4c), respec­tively, via ylide attack at the carbonyl carbon and subsequent transylidation. While 4a is isolable, 4b, c were detected only in solution. 4a is easily cleaved by Mel and MeOSO 2 F to give [Cp(CO)(tBuNC) 2 Fe]X and [Et 2 Me 2 P]X [X = I (5a); SO 3 F (5b)], which suggests preferred addi­tion of the carbon electrophile at the “ylidic” carbon, followed by dissociation of the carbon(acyl)- carbon(ylide) bond.

The aminovanadium(V) compounds VO(OR) 2 [NR'(SiMe 3 )] and VO(OR)[NR'(SiMe 3 )] 2 have been prepared by reaction of LiNR'(SiMe 3 ) with VO(OR) 2 Cl and VO(OR)Cl 2 , respectively; their spectroscopical data ( 1 H NMR, IR, MS) are reported. All compounds are monomeric in solution. In some cases 1.3 migration of SiMe 3 groups from nitrogen to oxygen is observed on heating. Kinetic measurements indicate the rearrangement reaction to be irreversible and intramolecular. The reaction of VO(OR)Cl 2 with HNR'(SiMe 3 ) leads to iminovanadium(V) compounds such as R'N = V(OSiMe 3 ) 3 , R'N = V(OSiMe 3 ) 2 (OR) and R'N = V(OR) 2 Cl.

The crown ether exchange could be studied in non-coordinating solvents by using the hy­drophobic complex [Co([18]crown-6)] + + . Appreciable outer-sphere association between complex and ligand (K°(50 °C) = 12 ± 0.5 M -1 ) occurs. This changes the second order rate law to first order (k mono (50 °C) = 7900 ± 500 s _1 ) with increasing ligand concentration. In the complex mer-[Co([18]crown-6)(CH 3 OH) 3 ] + + the stereochemical rearrangement of the uncoordinated part of the crown ether follows an intramolecular pathway via the complex [Co([18]crown-6)] ++ as an intermediate product.

Six 1′,1″-alkanediyl-bis(1′-alkyl-4,4'-bipyridinium) tetraquaternary salts have been prepared and their reduction and redox properties studied by polarography and cyclic voltammetry. They are reduced to radical trications and diradical dications at potentials (E c ) of about -0.20 V and -0.35 V, respectively.

Magnesium-COT reacts with diorganochlorophosphines to yield 1,2-diphosphino-substituted cyclooctatrienes. While the methyl compound leads to ring-concentration, larger substituents at phosphorus give rise to 1,8-diphosphino-octatetraenes (E, Z, Z, E) via retro-electrocyclization. The compounds are fully characterized by NMR.

UV-irradiation of decacarbonyl-dirhenium(0) (1) and acetylene in hexane yields a mixture of complexes, which were separated by preparative HPL-chromatography and characterized by elemental analysis, IR, NMR and mass spectroscopy. Main product of the reaction is octa- carbonyl-μ-(η 2:1 -ethynyl)-μ-hydrido-dirhenium(I) (4). Tricarbonyl-η 5 -methylcyclopentadienyl- rhenium(I) (2) and tetracarbonyl-2-3:9-η-(8,10-dinorborna-2,5-dien-9-yl)-rhenium(I) (3) are ob­tained in moderate yields. Minor by-products of the reaction are octacarbonyl-μ-hydrido-μ-η 2:1 - vinyl-dirhenium(I) (5), tridecacarbonyl-μ-η 2:1 -vinyl-trirhenium (6) and HRe 3 (CO) 14 (7). 4 shows a hindered ligand movement of the η 2:1 -ethynyl bridge, with ⊿G ≠ 250 = 48.2 kJ · mol -1 .

4-Bromo-1-(2,4-dinitrophenyl)-3-methyl-2-pyrazolin-5-one was reacted with the sodium salt of some reactive methylene compounds and then condensed with hydrazine hydrate, phenyl hydrazine, hydroxylamine hydrochloride, urea and thiourea to obtain the 4-substituted heterocy- cles-5-pyrazolones.

2-Hydroperoxides of cyclic esters react with pyridine-2,6-di(monothiocarboxylic acid) in form of its iron complex by attack of the thiocarboxylate anion at C-3, opening of the ether ring and formation of a thioester carrying a acyloxy group in the alcohol portion. A typical example is the formation of pyridine-2,6-di(monothiocarboxylic acid)-di-S-(3-formoxypropyl)ester from tetra- hydrofuran-2-hydroperoxide.

The photochemically induced rearrangement of the 4-diazoacetyl-2-azetidinones 2a-d in wa- ter/acetonitrile leads exclusively to the title compounds 3 a-d provided that certain reaction conditions are fulfilled. This is in contrast to the thermal, silveroxide catalysed Wolff-rearrange- ment of 2a in alcohols which always gives a mixture of 4, 5 and 6. The mechanism of the 1,4-ringopening of 2a to 5 and 6 is discussed.

Studies on model systems clearly revealed oxidative degradation of tryptophan under the usual conditions of iodination of tyrosine residues in peptides, whereby the rate of former reaction was found to be faster than the iodination itself. N in -formylation of tryptophan brings about an efficient indole protection against this oxidative degradation.

The title compounds were prepared (a) polycrys­talline by sintering the binary components and (b) single-crystalline by a wet chemical method. They crystallize in the space group Cmca with the lattice parameters a = 16.244(2), b - 5.342(1), c = 23.006(4) and 16.099(2), 5.296(1), 22.995(6) Å, resp. Their X-ray powder diffraction data are listed.

The X-ray structure of PPh 3 Me[NbOCl 4 (CH 3 CN)] at 210 K was solved (space group P1̄, two formula units per unit cell, a = 1173.5(5), b = 1130.1(4), c = 946.8(3) pm, α = 97.70(4), β = 93.57(3), γ = 78.62(3)°, 3688 inde­pendent reflexions, R = 0.025). The material consists of cations [P(C 6 H 5 ) 3 CH 3 ] ⊕ and anions [NbOCl 4 (CH 3 CN)] ⊖ . The nitrogen atom of the acetonitrile solvate molecule is coordinated to the niobium centre in the trans-position to the oxo ligand; the NbO bond length of 169 pm corresponds to a double bond.

Oxidation of (Me 3 Sn) 3 Sb in air gives (Me 3 Sn) 2 O and (Me 3 Sn) 4 Sb 2 in 45% yield.

Intercalation compounds of graphite with SnCl 4 have been prepared by reaction in SOCl 2 /CCl 4 or by UV irradiation in CCl 4 or 1,2-dichloroethane. Mix­tures of 1st, 2nd, and 3rd stages have been obtained. Chemical analyses and 119 Sn MöBbauer spectra indi­cate that SnCl 6 2- ions are intercalated. Solvent molecules are co-intercalated.

The functionalized ligands (H 3 C)PhP-(CH 2 ) n -Cl (1, 2) [n = 2 (1), 3 (2)] and Ph 2 P-CH 2 -OMen (3) with asymmetric phosphorus or carbon atoms which are suitable for the synthesis of diastereomeric metallacycles, are obtained in THF/ether by reaction of (H 3 C)PhPLi and Ph 2 PLi with Cl - (CH 2 ) n -Cl and Cl-CH 2 -OMen, respec­tively. The structures of 1-3 are discussed on the basis of their mass and NMR spectra.

The unit cell of NaNiAsO 4 is rhombohedral, space group R 3, with a = 4.955(5) Å, c = 26.47(3) Å and Z - 6. The crystal structure com­prises three-layer units consisting of one “octahe­dral" layer, built up from Ni0 6 -octahedra, and two “tetrahedral" layers, built up from AsO 4 -tetrahe- dra. Sodium ions are situated between these layers, having a distorted (4+3) coordination.

A nearly saturated solution of amidophosphoric acid in water hydrolyses to yield diammonium diphosphate. This reaction provides a diphosphate synthesis in water starting with a solution of N- methylcarbamoylphosphate which is readily ob­tained through the action of methylisocyanate upon the aqueous solution of a hydrogenphosphate.

A simple procedure for the preparation of tetra- kis(halomercuri)methanes C(HgX) 4 (X = F, Cl, Br and I) from Hofmann’s base (“oxymercarbide”) and aqueous hydrohalic acids is described. Under the reaction conditions used, degradation of the CHg4 moieties present in Hofmann’s base also occurs, in­creasing in the series HF ≈ HC1 < HBr < HI.

Methyl 7-oxo-5-trans-heptenoate reacts with diazomethane in the presence of Pd(CH 3 COO) 2 in high yield to the cyclopropane aldehyde 1, an im­portant intermediate in the 5,6-methanoleukotriene synthesis.

A new alkaloid, “papilicine”, has been isolated from the leaves of Buxus papilosa to which structure (1) has been assigned on the basis of spectroscopic studies.