Volume 31, Issue 8

The anionic complexes [olenFe(CO) 2 CN] - (olen = butadiene, 1,3-cyclohexadiene, cyclooctatetraene), formed by the reaction of olenFe(CO) 3 with NaN[Si(CH 3 ) 3 ] 2 , have been protonated to the isocyanic acid derivates olenFe(CO) 2 CNH, and alkylated with [Et 3 O]BF 4 to give the isonitrile complexes olenFe(CO) 2 CNEt.

The reaction of M(CO) 5 NCCH 3 (M = Cr, Mo, W) and C 7 H 8 Fe(CO)3 with sodium bis-[trimethylsilyl] amide does not lead to the transformation of a CO group into CN⁻, but instead, to a deprotonation to give the anions [M(CO) 5 NCCH 2 ]⁻ and [C 7 H 7 Fe(CO) 3 ]⁻.

The reactions of [C 7 H 7 Fe(CO) 3 ]- with alkyl chloroformates leads to the formation of ester substituted cycloheptatriene iron tricarbonyls 7-R-C 7 H 7 Fe(CO) 3 and 1-R-C 7 H 7 Fe(CO)3. In contrast, similar reactions with (C 2 H 5 ECl give only the 7-isomers (C 2 H 3 ) 3 E-C 7 H 7 Fe(CO) 3 (E = Si, Ge). The synthesis of the doubly ester-substituted cycloheptatriene iron tricarbonyl (C 2 H 5 OCO) 2 C 7 H 6 Fe(CO) 3 is described.

The new intermetallic compound Ca 2 As 3 has been prepared and its structure determined. Ca 2 As 3 crystallizes monoclinic, space group P2/c, Z = 8. In this compound the As-atoms form As 4 - and As 8 -chains in the ratio 1:1 in the unit cell. The building principle of the “anionic” part of the structure with respect to the Ca-contents matches with the concept of ZINTL, KLEMM and BUSMANN, so the compound belongs to the ZINTL-phases.

Ferrocene reacts with BI 3 and BBr 3 to give 1,1′-bis(dihalogenboryl)ferrocenes; the cyclopentadienylring in cymantrene is twice borylated by BI 3 . By halogen exchange with AsF 3 and AsCl 3 , by methylation with Sn(CH 3 ) 4 , by cleavage of (C 2 H 5 ) 2 O, by redox reaction with (CH 3 S) 2 and by reaction with (C 2 H 5 ) 2 NH the corresponding diborylferrocenes are obtained. The air-sensitive halogenborylferrocenes form donor-acceptor compounds with Lewis bases. 1 H, 11 B and 13 C NMR data reflect increasing π-acceptor properties with increasing Lewis acidity of the boryl groups.

The compounds NPClNCS(NSOF) 2 and NP(NCS) 2 (NSOF) 2 are prepared by reaction of cis-NPCl 2 (NSOF) 2 with KSCN. The mono(isothiocyanato) derivative obtained is a colourless liquid, consisting of two isomers in a ratio of 1:3.8; the bis(isothiocyanato) compound is a white crystalline solid.

57 Fe-MÖSSBAUER spectra of the cubic elpasolithes A 2 I NaFeF 6 (A I = K, Rb, Cs) show strong single line broadening in the temperature range 4.2 K ≤ T ≤ 600 K. This broadening is attributed to a statistical distribution of differently distorted FeF 6 3 -octahedra, causing a statistical distribution of electric fieldgradients at the 57 Fe-position. With the aid of a model calculation it was tried to estimate the order of the octahedral distortion. For the compound Rb 2 NaFeF 6 normal to the cell axis an anion displacement of Δ q = 0.11 Å from the regular octahedral position was derived from the Mössbauer data. This value agrees with the root mean square displacement ū = 0.13 Å, which results in this direction from the strongly anisotropic fluorine temperature factors found by X-ray structure determination.

The conproportionation of diaryl ditellurides and aryltellurium trihalides resulting in aryltellurenyl halides has been investigated using conventional and isotopo tracer methods. The aryltellurenyl halides are in general unstable and disproportionate to diaryltellurium dihalides and elementary tellurium.

1 reacts with SCl 2 to yield 2. The methylsilane derivatives [OC–NCH 3 –CO–NCH 3 -SO 2 –N] n Si(CH 3 ) 4-n for n = 2, 3 and 4 are readily prepared from 1 and (CH 3 ) 2 SiCl 2 , CH 3 SiCl 3 and SiCl 4 . The IR and mass spectra are reported.

Three new intermetallic compounds CaMnGe, SrMnGe and BaMnGe have been prepared. They crystallize tetragonal in the anti-PbFCl-structure type with the following constants : CaMnGe: a = 4.23(1); c = 7.27(1); c/a = 1.72, SrMnGe: a = 4.40(1); c = 7.52(1); c/a = 1.71, BaMnGe: a = 4.50(1); c = 7.92(1); c/a = 1.76.

Li 6 UO 6 has a reversible phase transformation at 680°C and decomposes above about 850°C. At high pressure the low temperature modification becomes unstable because of an invariant point in the system Li 2 O—Li 4 UO 5 at approximately 13 Kb and 620°C. β-Li 6 UO 6 has a triclinic unit cell with a = 5.203, b= 5.520, c = 5.536 Å, α = 114.7, β = 120.7 and γ = 75.5°. The close relationship between the crystal structures of Li 6 TeO 6 and Li 6 UO 6 is also suggested from similar infrared spectra and from partial solid solution Li 6 UO 6 —Li 6 TeO 6 .

The spirobi(benzodioxaphosphole) system stabilizes high phosphorus coordination. Thus bis(o-phenylenedioxy)chlorophosphorane adds pyridine in a fast first step without dissociation to a neutral, and in a slower second step to a cationic hexacoordinate phosphorus species. The equilibria compositions were determined by 31 P NMR. The cation of the bis(pyridine) adduct can be isolated as the stable crystalline chloride which partly decomposes on dissolving. More stable, even in boiling water, is the cation of the 2,2′-bipyridine adduct. 1 H NMR studies of the bis(pyridine) adduct lead to a cis structure. A δ 31 P comparison for hexacoordinate spirobi(benzodioxaphospholes) is given.

The hitherto unknown compounds SrCa 2 Yb 10 O 18 (1) and SrCa 2 Lu 10 O 18 (2) were prepared and examined by X-ray single crystal structure (Space group C 6⁻ 6 P6 3 , a = 1745.2; c = 333.0 pm (1), a = 1740.4; c = 330.7 pm (2)). 1 and 2 are isostructural with SrCaSc 6 O 12 , but there is a statistical distribution of Yb 3+ and Ca 2+ or Lu 3+ and Ca 2+ , respectively. It explains the same structure but the differences between the formulas of 1, 2 and SrCa 2 Sc 6 O 12 .

Single crystals of Ba 9 Cu 7 O 15 Cl 2 were prepared and investigated by X-ray diffraction methods. They crystallize with hexagonal symmetry (a =1125.7; c = 585.3 pm, Space group D 6h 2 -P6/mmm). Cu 2+ has the well-known square O 2- -coordination. The squares are connected to rings of 6-fold symmetry. Another Cu 2+ has a so for unknown coordination of 12 O 2- -neighbours. The differences in respect of other oxohalogenocuprates are discussed.

A series of bis-carbene complexes cis-M(CO) 4 L 2 (M = Cr, Mo, W) containing cyclic carbene ligands (L= 1,2-dimethyl-4-pyrazoline-3-ylidene, 1,3-dimethyl-4-imidazoline-2-ylidene, 2,4-dimethyl-1,2,4-triazoline-3-ylidene and 1,3-dimethyl-benzimidazoline-2-ylidene) was prepared, and the photo-induced conversion to the corresponding trans-isomers was investigated. The trane-M(CO) 4 L 2 complexes were characterized by their IR and 1 H NMR spectra, and their irreversible thermal isomerisation to the thermodynamically more stable cis-isomers was studied both in solution and in the solid state.

Trichloroacetimidicacidmethylester reacts with antimony(V) chloride to yield the 1-trichloromethyl-1-methoxi-methylenimonium-hexachloroantimonate(V) (1). 1 eliminates methylchloride and gives the 1:1-adduct (3) of trichloroacetamide and antimony(V) chloride. The vibrational spectra of 1 and 3 are communicated.

Charge transfer excitation of aqueous benzylpentacyanocobaltate(III) led to a redox reaction with formation of Co(CN) 5 3- and benzyl radicals in the primary photochemical step. In the absence of oxygen the benzyl radicals dimerized to bibenzyl. At 313 nm irradiating wavelength the quantum yield was 0,13 ± 0,02. In the presence of air oxygen was apparently inserted into the carbon-cobalt bond with the intermediate formation of [Co(CN) 5 O 2 CH 2 C 6 H 5 ] 3- , which decomposed to give Co(CN) 5 H 2 O 2- and benzaldehyde (ɸ = 0,15 ± 0,02). The significance of these results is discussed with regard to the photochemistry of acidopentacyanocobaltates(III) and organocobalamins.

Supported heterogeneous hydrogenating catalysts of high activity and stability can be prepared by reduction of RhCl(PØ 3 ) 3 , RhCl 3 x H 2 O or IrCl 4 X H 2 O in cyclohexene or cyclohexane. [With these catalysts substrates are hydrogenated without solvent]. With these catalysts substrates are hydrogenated without solvent, and turnover numbers are higher 20,000.

In comparison with (C 6 H 6 )Cr(CO)3, (C 6 H 6 ) 2 Cr is relatively light stable. The major part of the light energy absorbed by (C 6 H 6 ) 2 Cr leads neither to its decomposition or ligand exchange, nor can it be transferred to common low energy triplet acceptors. Internal dissipation of energy, either by rapid conversion to the ground state or by rapid reversible isomerization, must be an important process. In the case of (C 6 H 6 )Cr(CO)3, the main pathway to the previously reported lightinduced exchange of benzene involves an intermediate which is suggested to be (benzene)-dicarbonylchromium (1) and not a one-step dissociation of the excited molecule, to give Cr(CO) 3 and benzene 1b : 1 is also of major importance for the exchange of CO.

The consecutive formation constants of 1:1, 2:1, 3:1 chelate species formed by the interaction of di-p-tolyl-thiovioluric acid (D-p-TOTVA) with the tripositive lanthanons and yttrium cations were determined potentiometrically at 0.1 µ (NaClO 4 ) at 30± 1°C, in 75% aqueous dioxan. The 1:1 formation constants (log K 1 ) for the complexes increase with the increase in the atomic number of the lanthanon (3), with a break at gadolinium. The results indicate that the ligand bonds bidentately to heavier lanthanons (smaller ionic radii). However, definite dentate character of bonding to lighter (larger ionic radii) lanthanons could not be established.

The preparation of mer-[OsX 3 B 3 ], X = Cl, Br, I; B = pyridine, 3-resp. 4-picoline, pyrimidine, pyrazine, methylpyrazine, and the chromatographic isolation of four basemixed stereoisomers mer-[OsX 3 (py) n (mepyz) 3-n ], n= 1, 2, as solid crystalline products is described. Mass spectra and ligand exchange reactions confirm the structure of these complexes. The UV and IR spectra are discussed.

The IR and NMR spectra of rubazonic acids 1 and 2 show that these compounds form only OH tautomers in nonpolar solvents and in the crystalline state. They are stabilized by a strong intramolecular hydrogen bond in an eight-membered ring. The IR and NMR spectra show that they exhibit a symmetrical structure. The hydrogen bond has a double minimum potential. Alteration of the symmetry of substitution in 1- and 1′-positions markedly influences the signal of the OH proton. This symmetry effect is discussed.

Conformational Stability, 1 H NMR o,o′-Bis(phenylethynyl)-triphenylphosphineoxide, coordinated to Pd(II) with the P=0-group, is isomerized in boiling xylene to the condensed phosphepin- and dihydrophosphocin oxides (4) and (6). The structure of 6 is determined by catalytic hydrogenation, 1 H NMR and confirmed by an X-ray analysis, currently carried out. The hydrogenated products 7A and 7B are conformational isomers. The kinetic data of the ring inversion 7 A ⇄ 7B are determined.

Photokinetic experiments show that the deamination reaction of a series of 4-Amino-3-methylthio-1.2.4-triazin-5(4 H)-ons (1 a—e) is dependent on oxygen and nature of solvent. Experiments with a series of 6-tert-Butyl-3-methylthio-1.2.4-triazin-5(4 H)-ons (3 a—e) indicate that the formation of 6-tert-Butyl-3-methylthio-1.2.4-triazin-5-ons (2 d) occurs only in the case of an N—N-bond, but is, however, completely independent of the substituent on the nitrogen atom which is split off.

The stereochemistry of the ‘phosphine oxide cleavage’ of 37 different chiral acyclic quaternary phosphonium salts under various reaction conditions is presented and discussed.

The separation of an unsymmetrically substituted triarylphosphine, phenyl-m-carboxyphenyl-p-biphenylyl-phosphine (1), into its enantiomers is reported.

VILSMEIER-HAACK: formylation of 2,3-diphenylbenzofuran (la) gave the 5,6-diformyl derivative (lb). Huang-Minlon reduction of lb yielded the 5,6-dimethyl derivative (1c). Oxidation of 1c followed by hydrolysis the 2-hydroxy-4,5-dimethylbenzophenone (2b) was obtained. Condensation of lb with primary amines gave the corresponding Schiff bases (3 a-j). 1a on bromination gave 5-bromo-2,3-diphenylbenzofuran (1 d), which on hydrolysis via oxidation yielded 2-hydroxy-5-bromobenzophenone (2 d). 1d was also obtained by condensation of benzoin and p-bromophenol in presence of sulphuric acid. Conrad-Limpach reaction of 5-methoxy-6-amino-2,3-diphenylbenzofuran (1e) and ethyl acetoacetate gave 2,3-diphenyl-7-methyl-5-methoxy-9-hydroxy[2,3-f]furoquinoline via the azomethine (4).

Benzylidene aniline reacts with Ac 2 O/AcOH yielding 2-phenylperhydro-s-triazin-4,6-dione (“benzalbiuret”). Thiourea or N,N-dimethylsemicarbazide give the corresponding 8-triazines in a similar way. However, the reaction with cyanamide leads to N-benzylidene carbamic acid nitriles.

The new intermetallic compound SrSb 2 has been prepared and its crystal structure determined. The “anionic” part of the structure consists of (Sb - )-zigzag-chains, so the compound belongs to the “Zintl-phases”.

Single crystals of SrO - 3.5 Fe 2 O 3 - 2.5 Al 2 O 3 were prepared and investigated by X-ray diffraction. The atomic distribution differs from former investigations of magnetoplumbite compounds.

With a catalyst-system, prepared by reaction of NiCl 2 · 6 H 2 O and NaBH 4 in dimethylformamide a number of unsaturated compounds are hydrogenated under mild conditions quite efficiently. At 25°C hydrogenation of unsaturated ketones like mesityloxide is selectively regarding the double bond. Aldehydes are hydrogenated at 25 °C and some ketones at 60°C very slowly.

The 13 C high resolution NMR spectra of five alkylated ferrocenes have been recorded and analysed. The different n J(CH) were determined and used for a generally applicable assignment of five-ring carbon resonances.

The 13 C NMR spectra of seven phenylated paramagnetic metallocenes have been recorded. From the spectra the 13 C hyperfine coupling constants A( 13 C) have been extracted and compared with corresponding A( 1 H). It is found that the phenyl A′s in nickelocenes and cobaltocenes behave as in benzyl radical being reduced by a factor of 27. This offers a new route to informations about spin density distribution in substituted methyl radicals.

The space group of 4-iodo-2′,4′,6′-trimethylbiphenyl was determined by means of an automatic single crystal diffractometer as P 2 1 /c with 4 molecules in the unit cell and the molecular structure was refined to a R-value of 3.3%. The angle of twist between the two best planes of the phenylrings is 84 ± 1°.

Methyl- and benzylesters of acid labile amino acids are obtained as their hydrochlorides or BF 3 -complexes by reaction of the N-protected amino acid with benzylalcohol (methanol), DCC, HOBt and pyridine and subsequent cleavage of the N-protection group by HCl in acetic acid or bortrifluorideetherate in acetic acid.