Volume 45, Issue 3

The crystal structures of Me 2 NSF 2 ⁺ AsF 6 ⁻ (4) and CF 3 SF 2 + AsF 6 ⁻ (6) are reported and the cation structures compared with those of the corresponding isoelectronic neutral phosphanes.

The compounds K 20 Ga 6 Sb 12,66 and K 20 Ga 6 As, 12,66 have been prepared from the elements and the crystal structures were determined by single crystal X-ray diffraction a = 1780.0(5), (1678.0(5)) pm, c = 543.8(2), (524.5(2)) pm, P6 3 /m, Z = 4. The structures contain oligomeric anions Ga 3 As 6 9- and Ga 3 Sb 6 9- , which are isoelectronic to B 3 O 6 3-

The IR- and Raman spectra of the ten chloro-bromo-osmates(IV) [OsCl„Br 6-n ] 2- , n = 0-6, including the geometrical isomers for n = 2, 3, 4 have been recorded at low temperature (80 K). The vibrational spectra of these complexes are completely assigned according to point groups O h , D 4h , C 4v , C 3v and C 2v , supported by normal coordinate analyses based on a general valence force field. Due to the stronger trans-influence of Br as compared to Cl, in all asymmetric Cl—Os—Br axes the Os—Br bonds are strengthened and the Os—Cl bonds are weakened, indicated by valence force constants for Os— Br approximately 6% higher, for Os—Cl 6% lower, as compared with the values calculated for symmetrical Br—Os—Br and Cl-Os-Cl axes, respectively. The significantly stronger interaction between opposite bonds is revealed by the stretching interaction constants f dd , which are about three times larger than f dd for bonds at right angles.

Strong C—Sn hyperconjugation in C-stannylmethyleneborane 3 is indicated by (1) a small B—sp 2 C—Sn bond angle (105.6°), (2) a long sp 2 C—Sn bond (216 pm), (3) a very short B=C double bond (131 pm), (4) a very small coupling constant 1 J( 119 Sn- 13 C) = 125 Hz for the sp 2 C—Sn bond and (5) shielding of the boron atom of the B=C double bond by 20 ppm as compared to methyleneboranes without strong hyperconjugation. The boron atoms of the B=C double bond of 3 and related methyleneboranes act as π-donor and σ-acceptor, the substituents X at the carbon atom of the B=C double bond as π-acceptors and, through their C—X σ-bonds, as σ-donors. The partly bridged methyleneborane 3 closes the gap between unbridged and bridged methyleneboranes. Relationships to non-classical carbocations are pointed out.

1λ 3 ,3λ 3 -Diphosphanes of the type R 2 PCF 2 P(H)CF 3 [R = Me (3), Et (5), Cyclohexyl (6), Ph (7)] are formed in acceptable yields (40-75%) by reacting perfluoro-2-phosphapropene F 3 CP=CF 2 (1) with the corresponding secondary phosphanes R 2 PH. By reaction with sulfur, compounds 3, 5 and 7 selectively yield the corresponding monosulfur derivates R 2 P(S)CF 2 P(H)CF 3 [R = Me (8), Et (9), Ph (10)]. Treatment of 3 or 7 with dimethylamine (molar ratio 1/2) leads via HF elimination and addition of Me 2 NH to the aminophosphanes R 2 PCHFP(NMe 2 )CF 3 [R = Me (11), Ph (12)]. In a similar procedure HF has been eliminated from 3 by 1,4-diazabicyclo[2.2.2]octane (DABCO), and on addition of methanol or ethanol to the 1,3-diphosphapropene intermediate, the alkoxy compounds Me 2 PCHFP(OR)CF 3 [R = Me (13), Et (14)] have been obtained.

The orthoborate ion [B(OH) 4 ]⁻ in aqueous solutions between pH 5 and 12 forms stable boric acid esters with catechole and the catecholamines DOPA, α-methyldopa, dopamine, noradrenaline, adrenaline, and adrenalone. The stoichiometries of the esters in solution, their dependence of pH value and concentration were evaluated by 11 B NMR spectra and confirmed by Raman investigations in the catechole system. Additionally, Raman spectra and crystal structure investigations on solid crystalline esters confirm these results. The 1:1 esters show in the 11 B NMR spectrum a chemical shift δ of around 8.1 ppm, the 2:1 esters of around 13.5 ppm. The Raman spectra of the catechole ester show lines at 744 cm -1 , 826 cm -1 , and 1011 cm -1 for the 1:1 ester as well as at 798 cm -1 and 840 cm -1 for the 2:1 ester. Besides the 1:1 and 2:1 ester, a 3:1 compound is found as a solid for catechole. Raman spectra of this compound, unstable in aqueous solution, showed a superposition of the 2:1 ester and free catechole. The crystal structure of the triethylammonium salt, which is monoclinic, space group Cc = C s 4 (No. 9) with a = 925.3(3), b = 1781.1(2), and c = 1444.4(2) pm; β = 94.22(4)°; Ζ = 4; D c = 1.229 Mg · m -3 , shows that two molecules of catechole are esterified with the orthoborate ion in the form of a spiran-like four-coordinated boron atom, while the third molecule of catechole is freely inserted into the crystal. The crystal structure of adrenaloneborate-monohydrate, which is also monoclinic, space group P2 1 /c = C 2 h 5 (No. 14) with a = 942.4(4), b = 888.1(3), and c = 1337.8(3) pm; β = 96.86(5)°; Ζ = 4; D c = 1.452 Mg-m -3 , shows two condensed rings, the aromatic ring being condensed through the two phenolic O atoms with the boron atom, so building a dioxaborolane ring. The two OH-groups at the boron atom build Η-bridges with the water molecule. It may be a zwitter ion with a negative boron atom and a positive nitrogen atom.

Protonation constants were determined pH-metrically for 3 selected phosphinic acids of the type CHRP*—CHP* 2 (R = phenyl, methyl, t-butyl; P* = CH 3 P(O)OH). Complex formation equilibria were studied for metal ions Mg(II), Ca(II), Sr(II), Ba(II), Cu(II), Zn(II), Al(III) and Ga(III). Particular strong complex formation was observed for Ga(III).

Two cyclopentadienes have been linked in a stereochemically rigid arrangement such that the cyclopentadienes are not coplanar. The key intermediates in the synthesis were tetrakis(methylene)bicyclo[2.2.2]oct-2-ene (12) or -octane (14). The access to 12 and 14 was investigated in a comparative study including nine different precursors which were expected to lead to the methylene groups by elimination of HX. The best results were obtained with X = mesylate with overall yields of 52% for 12 in three steps and 42% for 14 in four steps. Other leaving groups facilitated the procedures, but more steps were required or the yield was lower. During these studies 21 tetrasubstituted bicyclo[2.2.2]oct-2-enes and -octanes were obtained and characterized, in particular by the δ( 13 C) and in most cases the 1 J( 13 C – 1 H) and δ( 1 H) values. Both 12 and 14 added CBr 2 selectively in that only isomers with two dibromo-(vinyl)cyclopropane fragments per molecule were obtained. One isomer showing C 2 -symmetry could be isolated from the mixture. After reaction with methyllithium the corresponding linked cyclopentadienes with unsaturated (20) or saturated bridge (21) were obtained and fully characterized. Metallation of 20 and 21 gave the title dianions in quantitative yield.

The Raman and 27 Al NMR spectra of the title substances have been investigated with special regard to the earlier postulated [Al 2 Cl 7 ] - ion. The Raman spectra represent a superposition of the spectrum of the [AlCl 4 ] - ion as well as of AlCl 3 (s). Likewise the 27 Al NMR spectra indicate AlCl species with coordination number 4 and 6 of Al. It is concluded that the postulated [Al 2 Cl 7 ] - ion with an Al–Cl–Al bridge does not exist in the compounds investigated. The literature concerning [Al 2 Cl 7 ] - is critically reviewed.

A new entry to low-valent, carbonyl-free tungsten phenylcarbyne complexes has been developed from W(CO) 6 via tungsten(II) alkyne complexes. The first step includes thermal decarbonylation of W(CO) 6 to fac-W(CO) 3 (MeCN) 3 and subsequent substitution of the acetonitrile ligands by EtNC or t-BuNC to give fac-W(CO) 3 (EtNC) 3 (1 a) or fac-W(CO) 3 (t-BuNC) 3 (1 b) in almost quantitative yields. Advantages of this indirect synthesis of 1 a and 1 b from W(CO) 6 are discussed in comparison to the previously described, CoCl 2 catalyzed transformation of W(CO) 6 with RNC to fac-W(CO) 3 (RNC) 3 . Compounds 1 a and 1 b are then quantitatively converted with Br 2 to W(CO) 2 (EtNC) 3 (Br) 2 (2 a) and W(CO) 2 (t-BuNC) 3 (Br) 2 (2b). 2 a and 2b react subsequently with PhC=CBr to give upon elimination of both CO ligands the carbonylfree compounds W(EtNC) 3 (η 2 -PhC=CBr)(Br) 2 (3a) and W(t-BuNC) 3 (η 2 -PhC=CBr)(Br) 2 (3b) in good yield. 3 a and 3b represent rare examples of complexes containing a 1-haloalkyne ligand. They are susceptible to nucleophilic attack at this ligand. Thus reaction of 3 a and 3 b with t-BuNH 2 or Et 2 NH gives the 1-aminoalkyne complexes W(EtNC) 3 [η 2 -PhC=CNH(t-Bu)](Br) 2 (4a), W(t-BuNC) 3 [η 2 -PhC≡CNH(t-Bu)](Br) 2 (4 b) and W(t-BuNC) 3 (η 2 -PhC=CNEt 2 )(Br) 2 (4c) in good yields. Finally a base-induced cleavage of the alkyne ligand is achieved in 4 a and 4b using LiPh and gives the carbyne complexes mer,trans-Br(t-BuNC)(EtNC) 3 W=CPh (5a) and trans-Br(t-BuNC) 4 W=CPh (5b). This decoupling reaction is the first example of an alkyne-bond cleavage to C 1 -fragments at a single transition metal center and the key step in the new synthetic procedure to 5 a and 5 b from W(CO) 6 . Complex 5 b has been previously prepared from W(CO) 6 by the classical Fischer route via the carbonyl containing carbyne complex trans-Br(CO) 4 W=CPh and has been shown to undergo the reverse of the decoupling reaction i.e. an H Br-induced coupling of a tert-butylisocyanide with the phenylcarbyne ligand to form 4b. The compositions and structures of the complexes 1 a-5b have been determined by total elemental analyses, IR, 1 H NMR, 13 C NMR and mass spectra. The spectroscopic results indicate a substantial bond delocalization in the 1-aminoalkyne complexes 4a-4c and a hindered rotation of the diethylamino group in the alkyne ligand of 4c. The barrier to this rotation is calculated to be ca. 14.7 kcal/mol and compared with previously reported diethylaminoalkyne complexes. An X-ray crystallographic study of 5 b has been carried out. The compound crystallizes in the monoclinic space group P 2 1 . The unit cell contains two molecules of 5 b, which have a distorted octahedral coordination geometry with a trans-arrangement of the bromo and the phenylcarbyne ligand. The four isocyanide ligands are slightly bent out of the equatorial plane towards the bromo ligand. Striking features of the structure are the shortest W=C carbyne and the longest W —Br bond lengths known for low valent tungsten aryl- and alkylcarbyne complexes indicating a high electron density at tungsten. In addition two isocyanide ligands show a bent geometry at nitrogen, which has been so far reported only for electron-rich isocyanide complexes.

The title compound is prepared from naphthazarine (5,8-dihydroxy-1,4-naphthoquinone) and tetraphenylstibonium ethoxide (molar ratio 1:2) in dioxane as a solvent. X-ray analysis shows the naphthazarine dianion to act as a bifunctional chelating ligand in which two 2,2′-connected 1,3-diketonato groups are fixed in a coplanar position by two cis-ethenediyl bridges. The interaction of the naphthazarine dianion with the tetraphenylstibonium ions is an intermediate between ionic and covalent bonding. Consequently the antimony ions have strongly distorted octahedral coordination spheres (Sb–O 225,5(4) pm, Sb–C e 215,9(6) pm, Sb–C a 214,8(5) pm; O-Sb-O 75,9(1)°, C e – Sb– C e 103,8(2)°, C a –Sb–C a 166,0(2)°). The chelate rings are folded at the O/O axes (angles of fold 20-36°), the two antimony centers being arranged in trans-positions relative to the plane of the naphthazarine dianion.

The reaction of racemic jasmonic acid with either (R)-mandelic acid or its (S)-enantiomer resulted in a mixture of diastereomeric esters. Both the O-[(±)-jasmonoyl]-(R)-mandelic acids (2a, 2b) and the O-[(±)-jasmonoyl]-(S)-mandelic acids (3a, 3b) could be separated by silica gel chromatography. By hydrolysis of the pure diastereomers, resolved (+)-JA (la) and (–)-JA (lb) were obtained. The structures and the purity of all compounds were confirmed by 1 H NMR, MS, GC/MS, IR and ORD.

Continuing earlier studies designed to obtain derivatives of pharmacological interest, some novel compounds 2, 5, 6, 7 and 8 were prepared using 1,4-diphenylpyrrolidine-2,3,5-trione (1) and 1,2-phenylenediamines, o-aminophenol, 1,3-diphenylacetone and thiosemicarbazide, respectively. The hydrazino derivative (8) was obtained from 7 and hydrazine hydrate. Structural identification was obtained by 1 H NMR, mass spectra and IR spectral data.

Two new terpenoids pluchidione 1 and pluchidinol 2 were isolated from the ethyl acetate soluble portions of the whole plant of Pluchea arguta Boiss. The structures of these compounds were established by using modern spectroscopic techniques.

A novel synthesis of cinnolines by reacting arylidenemalononitrile derivatives with 1-aryl-1,6-dihydro-6-oxo-pyridazin-3,5-dicarbonitriles is reported.

Monomeric hydroxy-p-quinones (1) are in equilibrium with the corresponding o-quinones (2) and on methylation, a mixture of both isomeric ethers is obtained. In contrast, dimeric hydroxynaphthoquinones with the 3 a-skeleton in treatment with diazomethane are yielding only p-quinone ethers of type 3b.

An efficient two-step synthesis of some fluoro pyruvic acids monohydrates 6 is described. The reaction of fluoromethyltrimethylsilanes 3 with di-tert-butyl oxalate (4) in the presence of tetrabutylammonium fluoride as a catalyst produces intermediate siloxy products 5, which are converted by hydrogen chloride into 6. 3,3,4,4,4-Pentafluoro-2-oxo-butanoic acid monohydrate (6c) is obtained analogously by reacting pentafluoroethyltrimethylsilane (3c) with 4.

The title ligands, derived from monosaccharides and cysteine, form bis(chelate) complexes of palladium(II) and copper(II). According to their IR spectra the ligands are N,Ο-coordinated to copper(II), whereas N,S and O,S coordination to palladium(II) is observed.

The colourless compound Na 3 O(CN) has been prepared. The characterization by X-ray powder methods leads to a cubic primitive lattice (P m 3 m) with a = 456(2) pm (Z = 1). The structure is related to the anti-perovskite type.

Phase transfer catalytic (PTC) methylations of deoxybenzoin by dimethyl sulfate can be steered towards enol ether formation by large, sterically shielded ammonium ions or – more strongly – by large highly delocalized phospho-iminium (and presumably other large) cations. The C-alkylation direction is favoured by small, hard ammonium ions of the type RNMe 3 + and by crown ethers, particularly benzo-crowns. O/C ratios can be varied between 0,75 and 63, the largest effects so far reported for ambident anions. These results should give guide-lines for alkylations of other ambident ions.