Band 36, Heft 4

Crystals of the title compound are monoclinic (space group P2 1 /m) with a = 6.844(4) Å, 6 = 6.800(4) Å, c= 15.227(9) Å, y= 120.19° and Z = 2. The structure contains infinite cationic [(Te 12 O 22 ) 4+ ]∞ -chains with three different sites for tellurium. There are three oxygen atoms in a y-tetrahedral arrangement around Te 1, and four oxygen atoms in a ψ-trigonal-bipyramidal coordination around Te 2 and Te 3.

Bariumthioantimonate(III), Crystal Structure Ba 8 Sb 6 S17, prepared by fusion of the binary sulfides at 1120 K, crystallizes in the mono-clinic system (space group:P2/c) with a= 1141 ± 1 pm, b = 1373 ± 1 pm, c = 2253 ± 2 pm, β = 90.94 ± 0.05°. In the structure there are isolated distorted SbS 3 3- -trigonal pyramids (ψ-tetrahedra) and hitherto unknown Sb 3 S 8 7- -units consisting of a central SbS 4 -ψ-trigonal bipyramid connected by the common axial S-atoms with two further SbS 3 3- groups.

The new isotypic compounds BaGe 2 P 2 and BaGe 2 As 2 crystallize in the tetragonal system (P4 2 mc) with the following lattice constants: BaGe 2 P 2 : a = 761.8 ± 0.5 pm, c = 850.0 ± 0.5 pm, c/a = 1.12, BaGe 2 As 2 : a = 778.6 ± 0.5 pm, c = 866.4 ± 0.5 pm, c/a = 1.11. Fourbonded Ge atoms and twobonded P (As) atoms form a three-dimensional network. The Ba atoms are located in tubelike holes.

He(I) and He(II) photoelectron spectra are reported for (η 5 -C 5 H 5 ) 2 MLX (M = Nb, Ta; L = H, CO; X - propene, 1-butene, propyl) and some methylcyclopentadienyl deriva-tives. Also the spectra of some π-allyl and dihalide complexes are reported. Unambiguous assignments could be made of the metal d a 1 orbital, the Cp orbitals, the olefin π ionization and the M-hydride and π-allyl orbitals. Very regular trends are observed in the ionization energies upon substitution of the ligands. The olefin π ionization is found at very low energy indicating that the π backbonding to the olefin is very important. He(I)/He(II) cross section differences show clearly differences in metal character of the various M.O.'s.

Reactions of F 3 CSe(O)OAg with F n Cl 3-n CSCl (n = 3, 2, 1) give the compounds F 3 CSeS(O 2 )CF n Cl 3-n . These decompose in the range of- 20 °C to 39 °C to F 3 CSeCF n Cl 3-n plus SO 2 . IR, NMR and mass spectra of the newly prepared compounds are presented.

Cyanogen Halides The title compounds react with iodine to give the iodinecarbonyl complexes (η-C 5 H 5 )Co(CO)I 2 and (η-EtMe 4 C 5 )Co(CO)I 2 . The reactions of the same compounds with the cyanogen halides XCN (X = Br or I) give rise to the formation of mixed cyano-carbonyl complexes (η-C 5 H 5 )Co(CO)(CN)X and (η-EtMe 4 C 5 )Co(CO)(CN)X (X = Br or I) respectively. The compounds have been characterized by elemental analyses and IR and HNMR spectra.

The reactions of (η-C 5 H 5 ) 2 V with NO and XNO (X = CL or Br) lead to the formation of [η-C 5 H 5 V(NO) 2 ] 2 and (η-C 5 H 5 ) 2 VX(NO) (X = CL or Br) respectively. The compounds have been characterized by elemental analysis, magnetic moments and IR and EPR spectra.

The title compound has been synthesized from PhSnCl 3 and the disodium salt of bis(2-mercaptoethyl)ether. The crystal structure has been determined and refined to R - 0.033. The conformation of the eight-membered heterocycle is slightly disordered and represents a diplanar form, which is generally considered the transition state near the saddle point of the energy surface between the two enantiomers of the boat-chair con-formation. The configuration around tin is a trigonal bipyramid with equatorial sulfur atoms, an equatorial phenyl group and with axial atoms Cl and O (transannular distance Sn···O 241 pm).

Polymeric bis(dimethyl-and diphenylglyoximato)-complexes of Fe(II) and Co(II) with pyrazine as a bridging ligand have been synthesized. The Co(II) complexes are para-magnetic with μ = 1.83 B.M., and surprisingly stable against oxidation. Bis (dimethyl-glyoximato)pyrazine-cobalt (II) crystallizes monoclinic in the space group C2/m with Z = 2. The crystal structure shows linear chains of alternating Co atoms and pyrazine ligands. Perpendicular to the chain, the Co atoms are coordinated in a square planar arrangement by two dimethylglyoximato ligands (Co-N= 189 pm), the local symmetry being C 2h -The long Co-pyrazine distance of 224 pm is in agreement with the fact that the compound is a 19 electron complex. The Co complexes do not have conducting properties. The Fe(II) complexes possess the same structure but with stronger bonds in the chain. They show very low conductivity of approximately 10 -10 cm -1 Ω -1 . The Mössbauer spectra of the Fe-complexes are reported.

Isolable chloro[(thio)alkoxy]triorganylphosphoniumchlorides RR 2 'P-X-CH 2 R"] + Cl - are synthesized by reaction of oxiranes (2-5) (oxetane (6), thiiranes (18a-c)) with dichloro-phosphoranes (1a-f). Structure and stability are discussed. Thermal Arbusov-rearrange-ment yields vicinal di-resp. trihalo-alkanes and phosphanoxides. The structures are confirmed by 31 P{ 1 H} and 13 C{ 1 H} NMR data.

The photo-induced reaction between the complexes [Et 4 N][V(CO) 6 ] (1), η 5 -C 5 H 5 V(CO) 4 (2), η 5 -C 5 H 5 Mn(CO) 3 (3) or η 5 -C 5 H 5 Mo(CO) 3 CH 3 (4) and the ligands o-C 6 H 4 EPh 2 (E'Ph 2 ) (E = E' = P: a; E = P, E'=As: b; E = E ' = As: C; E = P, E ' = S b : d; E = P, E ' = Bi: e; E = As, E' = Sb: f) and cis-Ph 2 PCH = CHPPh 2 (g), L, yields - depending on the steric requirement of L - the compounds (M}L ({M} = cis-V(CO) 4 -, cis-CpV(CO) 2 , CpMn(CO), CpMo(CO)CH 3 ; L = a, b, c, g), {M'}L ({M'} = V(CO) 5 -, L - d; {M'} - CpV(CO) 3 , L - d, e; {M'} = CpMn(CO) 2 , L = e) or mixtures of {M}L and (M'}L ({M}, {M'} = V(CO) 4,5 , L = e,f; {M}, {M'} = CpV(CO) 2,3 , L = f). In the mono-substituted species {M'}L coordination (as indicated by the 51 V NMR spectra) occurs through EPh 2 and E'Ph 2 , which is explained by a reaction path via a labile chelate 5-ring structure. Shielding of the 51 V nucleus decreases in the order g > SbPh 2 > PPh 2 > AsPh 2 > BiPh 2 (derivatives of 1) and g > SbPh 2 > PPh 2 > BiPh 2 >AsPh 2 (derivatives of 2), and is smaller in the rigid chelates incorporating the o-phenylene ligands than in the more flexible structures of phospha- and arsabutane complexes. This fact is discussed in terms of hindered σ-overlap due to distortion of the EVE angle, which also results in an increase of CO valence force constants in rigid chelates. 31 P coordination shifts increase according to dppe < a < g and arphos < b (dppe = Ph 2 P(CH 2 ) 2 PPh 2 , arphos = Ph 2 As(CH 2 ) 2 PPh 2 ). 31 P NMR spectra of the molybdenum complexes suggest that the basic geometry for 4a and 4b likely is tetragonal pyramidal, while the preferred structure for 4g appears to be the trigonal bipyramid with the ligand in equatorial positions. The crystal and molecular structure of 1a is reported. The complex crystallizes in the space group C2/c (a = 2196.0, b= 1080.1, c = 2022.7 pm, β= 124.6°). The most striking result is the small PVP angle of 80.8 (0.2)°. Optimized methods for the synthesis of the ligands a-f are described; the ligands are characterized by their mass spectra.

The structures of GdAsSe and NdAsSe were determined from single crystal data. GdAsSe crystallizes in the monoclinic CeAsS-type structure. The deviations from the parent tetragonal ZrSiS-type structure are smaller than in the corresponding sulphides. The As-As distances in the infinite arsenic chains appear to be too large to warrant non-metallic properties. The structure of NdAsSe is isopuntal with the CeAsS-type; however, only As pairs can be identified. The CeAsS-type structure was also found in the LnAsSe compounds with Ln = Pr, Sm, Tb, . . ., Tm, Lu, Y. The distortions of the ZrSiS-type substructure become more pronounced on going to smaller cations. The stoichiometry of the samples depends strongly upon the preparation.

Several 1,3,5-triaza-2-boracyclohexa-4,6-diones have been prepared by condensation reactions of boranes with biurets; N-methylated species could be characterized by their 1 H, 11 B and 13 C NMR spectra. Some data are also reported on bicyclic bis(N,N',N"- trimethylbiuret-1,5-diyl)borate(l-) salts and on a betaine consisting of two N,N',N"-trimethylbiuret moieties bonded to a central four-coordinate boron atom.

Tetrafluoroborate complexes (η 5 -C 5 H 5 )Mo(CO) 2 (PR 3 )FBF 3 have been prepared by hydride abstraction from the corresponding hydrido compounds using Ph 3 CBF 4 . The tetrafluoroborate ligand in (η 5 -C 5 H 5 )Mo(CO) 2 (L)FBF 3 (L = CO, PR 3 ) is easily sub-stituted by phosphanes, cis-and trans-butene(2), a-acetamidocinnamic acid and buta-diene. Nucleophilic addition of HNMe 2 to the butadiene complex [(η 5 -C 5 H 5 )Mo(CO) 3 butadiene)] + BF 4 - gives the β-aminoacyl chelate compound 7.

The principle of electrochemical substitution of metal carbonyls has been applied to monosubstituted derivatives M(CO) 5 PR 3 (M = Cr, Mo, W) with the aim of selective prepa-ration of di-and trisubstituted products M(CO) 4 (PR 3 )(PR' 3 ) or M(CO) 3 (PR 3 )(PR' 3 ) 2 . It is shown that, due to simultaneous replacement of CO and PR 3 mixtures of products are formed.

Displacement of 2-methvlpropene from [Fp(Me 2 C = CH 2 )]BF 4 (Fp = (η 5 -C 5 H 5 )Fe(CO) 2 ) by Z-1,2-dimethoxyethylene (Z-DME) gives [Fp(Z-DME)]BF 4 . Displacement by E-1,2-dimethoxyethylene (E-DME), in contrast, does not give the expected complex of E-DME, but rather the complex of the Z-alkene. A mechanism involving scission of the C = C bond of the coordinated alkene to give a bis-carbene intermediate is proposed.

The use of two-dimensional NMR spectroscopy (2D-J) for the identification of isomers and heterocouplings is demonstrated. The routine application of this new method to practical NMR problems is discussed.

Part of the potential surface of S 4 N⊖ has been investigated using the MNDO method. It is found that the cis-trans isomer 1b is more stable by 20-30 kJ/mol than the trans-trans isomer (1 c) and the cis-cis isomer (1 a). The stability of 1 b is traced back to stabilization of the HOMO and to a Coulomb attraction. For S 3 N 2 O 2 (2) the MNDO calculations favour those isomers (2a and 2b) with two sickle-like arrangements for the same reasons. For S 4 N 3 e (3) only one isomer (3a) is favoured due to the stabilization of the HOMO. The similarity in the transannular interaction present in 1-3 and that in trithiapentalenes and related compounds is pointed out. The PE spectrum of 2 has been reinvestigated. The first five bands can be interpreted by comparison between the measured ionization potentials and the calculated (MNDO) orbital energies.

The degenerate rearrangement of P 7 3- has been studied by means of the MINDO/3 method. The calculated enthalpy of activation (⊿H≠ = 59.12 kJ/mol) is in good agreement with results from 31 P NMR studies at different temperatures. The bond switching process starts with a bond rupture leading to a transition state with C 2v symmetry. Possible rearrangements in P 6 S 2- and P 6 CH 2- are discussed.

Abstract 1 -Phenyl-4-carboxymethylmercapto-5-arylazo-hydantoin derivatives (3a-f) were cyclised with acetic anhydride to give the bicyclic products (4a-f). Compounds 4 a, b condensed with aromatic aldehydes in acetic acid and in presence of anhydrous sodium acetate yielding the corresponding arylidene derivatives (5a-c). Compounds 4a, b also couple with aryldiazonium salts to give the expected coloured arylazo compounds (6a-j). 4 a, b reacted with formaldehyde and primary aromatic amines in ethanol to give the corresponding Mannich bases (7a-f).

The photochemical behaviour of 5,6-Dehydrokawain (1) was investigated. An aceton solution of 1 was placed into a Petri-dish and allowed to evaporate. After a four weeks irradiation with a 100 W light bulb from a distance of 30 cm [1] the main component was isolated. Its structure and configuration is elucidated as r-1,c-2-di[6-(4-methoxy-2- pyronyl) ] - t- 3 ,t -4-diphenyIcyclobutane (2) by means of spectroscopic methods and correlation with β-truxinic acid after degradative reaction.

The formation of disulfide bonds in separate chemical steps in a cystine peptide containing several cystine residues is exemplified by the synthesis of human insulin. The synthetic methods which made this approach feasible were 1) the thiol-induced fragmentation of sulfenyl thiocarbonate derivatives and 2) the conversion of S-trityl- and S-acetamidomethyl cysteine peptides to cystine peptides by oxidation with iodine.

The interaction of RR'N-PCl 2 (1) with LiNR"SiMe 3 gives monomeric phospha(IH)-azenes RR'N-P=N-R"; R = R"=i-C 3 H 7 , R'= (CH 3 ) 3 C (3a); R=i-C 3 H 7 ,R'=R" = (CH 3 ) 3 C (3b); R = i-C 3 H 7 , R' = (CH 3 ) 3 C, R"=(CH 3 ) 3 Si (3c) as distillable liquids. 3a adds PCl 3 with formation of RR'N-PCl-NR-PCl 2 , R = i-C 3 H 7 , R'=(CH 3 ) 3 C (6).

(η 3 -Allyl) (η 5 -cyclopentadienyl) palladium reacts with bis(diphenylphosphino)maleic an-hydride to form a complex in which the C 5 H 5 ligand is inserted into a P-C bond of the phos-phine ligand. The high yield (>95%) suggests that this reaction takes place within the co-ordination sphere of palladium. The structure is studied by x-ray crystal structure analysis.

Tl 4 Ge 4 Se 10 crystallizes in space group C2/c with a = 15.602(6), b = 15.549(5), c = 9.052(3) Å, β - 107.10(3)° and Z = 4. The compound was prepared by fusion of a stoichiometric mixture of Tl 2 Se and GeSe 2 . The crystal structure is characterized by adamantane-like anions [Ge 4 Se 10 ] 4- and Tl + cations. Tl 4 Ge 4 Se 10 is iso-structural with Tl 4 Ge 4 S 10 [1].

Dihydrokaempferol ((2R, 3R)-2-(4-Hydroxy-phenyl)-3,5,7-trihydroxy-4-chromanon) has been isolated from the fruit of Silybum marianum L. Gaertn. and identified by UV, CD, MS and PMR spectra.