Volume 52, Issue 9

Forty eight new compounds RT 2 Zn 20 were prepared by annealing cold-pressed pellets of the elemental components in an argon atmosphere. They crystallize with the cubic CeCr 2 Al 20 type structure (Fd3̅̅m , Z = 8), which was refined from single-crystal diffractometer data of TbFeiZn 20 (a = 1411.1(1) pm ), YRu 2 Zn 20 (a = 1422.6(1) pm ), DyRu 2 Zn 20 (a = 1422.1(1) pm), GdCo 2 Zn 20 (a = 1406.0(1) pm ), DyRh 2 Zn 20 (a = 1418.2(1) pm ), and TmNi 2 Zn 20 (a= 1401.6(1) pm) to conventional residuals varying betw een R = 0.011 and R - 0.024. The com pounds have a tendency for tw inning, thus m im icking hexagonal sym metry, with the cubic [111] axis as the axis w ith the pseudohexagonal symmetry. M inor inconsistencies in the cell volum es of these com pounds indicate slight deviations from the ideal com position. N evertheless, the five atom ic sites of this structure w ere found to be fully occupied w ithin the error lim its w ith the exception of one zinc site of TmNi 2 Zn 20 . The coordination for the site of the rare earth atom s is a Frank-K asper polyhedron with coordination num ber (CN) 16. The transition metal atom s occupy a site w ith icosahedral zinc coordination (CN 12). Two of the three zinc sites are in pentagonal prism atic coordination of zinc atom s, capped by rare earth and/or transition metal atom s (CN 12), w hile the third zinc site has 12 zinc neighbors form ing a hexagonal prism , w hich is capped by tw o rare earth atom s (CN 14).

K 3 BiO 3 and Rb 3 BiO 3 have been synthesized for the first time by solid state reactions of the respective binary compounds. K 3 BiO 3 was obtained from Bi 2 O 3 and K 2 O at 550 °C, Rb 3 BiO 3 from Bi 2 O 3 and Rb 2 O at 650 °C. The compounds were structurally examined by single-crystal X -ray investigations (K 3 BiO 3 : I 4̅ 3 m, a = 1070.15(2) pm, Z = 8; Rb 3 BiO 3 : P 2 1 3, a = 875.48(2) pm, Z = 4). The structures reveal “isolated” BiO 3 3- groups. While K 3 BiO 3 is isostructural to Na 3 BiO 3 , Rb 3 BiO 3 has the same crystal structure as Cs 3 BiO 3 .

Mixed manganese sandwich complexes containing a silyl-substituted cyclopentadienyl ring, e. g. (η 5 - C 5 H 4 - R)Mn(η 6 - C 6 H 6 ) (3a - c) and (η 5 - C 5 H 4 - R)Mn(η 6 - C 6 H 5 - Ph) (4a - c); (R = SiMe 3 (a), Si 2 Me 5 (b) and SiMe 2 t Bu (c)), were obtained in low yield via intermediates {(η 5 - C 5 H 4 - R)MnCl} and their reaction with phenyl Grignard reagents. Use of the 4-trimethylsilyl-phenyl magnesium halide in the reaction with the intermediate {CpMnCl} led to complexes with silylsubstituted arene rings, CpMn(η 6 - C 6 H 5 - R′) (5a) and CpMn(η 6 -R′ - C 6 H 5 - C 6 H 5 - R′) (6a); (R′ = SiMe 3 (a)). Dilithiation of CpMn 6 H 6 ) (1) and subsequent reaction with a chlorosilane gave (η 5 -C 5 H 4 - R)Mn(η 6 - C 6 H 5 - R′) (7a,b); (R = R′ = SiMe 3 (a), Si 2 Me 5 (b)). A cyclophane 8 in which five- and six-membered ring are linked through a -Me 2 Si-SiMe 2 - bridge was obtained using 1,2-dichloro-tetramethyldisilane. The mixed manganese sandw ich complexes were thoroughly characterized by 1 H , 13 C, 29 Si and 55 Mn NMR spectroscopy. The 55 Mn spectra can be used to detect low-yield side-products.

Tridentate ligands having the donor set S ⌒ N ⌒ O(S ) were synthesized by cleavage of 3.5-diphenyl-1.2-dithiolium salts with (thio)benzoylhydrazine or 2-hydroxy-5-methyl-aniline. The ligands were characterized as their nickel chelates formed in the presence of triphenylphosphane. The same nickel compounds result by template reactions of dithiolium salt, nickel acetate and the corresponding amine component. Crystal structures were determined for thiodibenzoylmethane benzoylhydrazone 1a, [thiodibenzoylmethane benzoylhydrazonato(2-)]-triphenylphosphane-nickel(II) 1b, [thiodibenzoylmethane thiobenzoylhydrazonato(2-)]-triphenylphosphane-nickel(II) 2b and [thiodibenzoylm ethane 2- hydroxy-5-methyl-anilato(2-)] triphenylphosphane-nickel(II)ethanol 3.

In the reaction of monosilylhydrazines and aqueous form aldehyde solution the first monomeric and therm ally stable N-silylformaldehyde-hydrazones [1-3] are obtained.

The title com pounds have been prepared in partly new ways and their crystal structures determined. The molecular geometries are found similar to those of the respective gas phases and those obtained by ab initio calculations. On the intermolecular level, there are indications of weak hydrogen bonds P-H···F in all three structures and of likewise weak fluorine bridges P-F···P in PH 2 F 3 and PHF 2 with the latter further featuring a close P···P contact.

From 2-trimethylsilylimino-1,3-dimethylimidazoline (6, ImN-SiMe 3 ) and CSCl 2 the imidochlorothionic acid [ImN=C(S)Cl (7) is obtained; 7 gives with AlCl 3 the cationic isothiocyanate [ImN=C=S]AlCl 4 (9). The corresponding imidothiourea ImN=C(S)NEt 2 (12) is formed reacting Et 2 NC(S)Cl (10) and ImNLi (11). The reaction of ImN=C(S)SSiMe 3 (13) with iodine gives the dicationic species [{ImN=C(SSiMe 3 )S} 2 ](I 3 ) 2 (14) which is transformed into the protonated imidothiourea [ImN=C(S)N(H)Im]I (16) by polar solvents. From 16 the imidothiourea (ImN) 2 CS (8) is obtained as a polymeric solid. The strong π-electron donor ability of the imido substituent ImN is revealed by the X-ray structure analyses of 12 and 16.

By determination of the enthalpies of solution of lanthanum oxide and of lanthanum trihalides in 4n HX we derived the enthalpies of formation of the trihalides at 298 K using tabulated data. On the basis of these data and measured enthalpies of solution in 4n HX of diammonium lanthanum pentahalides, the enthalpies of formation of (NH 4 ) 2 LaX 5 were obtained. ΔH° B (LaCl 3,f,298 ) = -258,5 ± 0,8 kcal/mol; ΔH° B ((NH 4 ) 2 LaCl 5,f,298 ) = -411,5 ± 1,4 kcal/mol; ΔH° B (LaBr 3,f,298 ) = -218,7 ± 1,7 kcal/mol; ΔH° B ((NH 4 ) 2 LaBr 5,f,298 ) = -352,8 ± 2,5 kcal/mol; ΔH° B (LaI 3,f,298 ) = -166,9 ± 2,0 kcal/mol; ΔH° B ((NH 4 ) 2 LaI 5,f,298 ) = -264,7 ± 3,0 kcal/mol.

Single crystals of Ba 17 Dy 16 Zn 8 Pt 4 O 57 (I), Ba 17 Ho 16 Zn 8 Pt 4 O 57 (II), Ba 17 Er 16 Zn 8 Pt 4 O 57 (III) and Ba 17 YZn 8 Pt 4 O 57 (IV) have been prepared by high temperature reactions using platinum crucibles. X-ray investigations led to tetragonal symmetry, space group C 5 4h - I4/m, (I) - (IV): a = 22.905(1), 22.840(1), 22.795(1), 22.848(1) Å and c = 5.728(1), 5.722(1), 5.700(1), 5.709(1) Å,Z = 2. The crystal structure is characterized by small square, medium-sized quadrangular and large rectangular tunnels, which are filled by oxygen, barium and zinc. The polyhedra network is discussed with respect to the network of compounds of the Ba 13 Dy 8 Zn 4 Pt 4 O 37 type.

Using various criteria to characterize the terms aromaticity and anti-aromaticity it is shown that the non-benzoid aromatic azulene and the benzoid aromatic naphthalene should have anti-aromatic properties in the first excited singlet state.

Ligand exchange reactions of molybdenum hexacarbonyl with tridentate diacidic ligands were studied by means of photochemical and thermal activation. The reaction products were characterized by mass spectrometry. Species such as MoL 2 , MoH 2 L 2 and MoO 2 L could be identified.

The crystal structure of Rb 3 NbO 8 (SG I4̅2m, Nr. 121) has been determined on single crystals to a final R = 0.041. The structure is isotypic to the K 3 CrO 8 type. Vibrational spectra of the title compound have been recorded on powdered samples and are discussed with respect to the internal vibrations of the peroxo-group and the dodecahedral NbO 8 3- ion. The stretching vibrations of the O 2 2- groups are found at 838 (Raman) and 813 cm - 1 (IR). A factor group analysis for the K 3 CrO 8 type is given.

Pressure dependence of the electrode potentials for various M 3+/2+ couples (M = Fe, Co, and Ni with o-phenanthroline, bipyridine, terpyridine, 1,4,7-triazacyclononane, and 1,4,7-tri-thiacyclononane) was measured by cyclic voltammetry in aqueous solution vs. a Ag/AgCl reference electrode. The reaction volume of the Ag/AgCl reference electrode was estimated from the change in the partial molar volumes of Fe aq 3+/2+ and Co(terpyridine) 2 3+/2+ couples, and the volumes for the formation of M 2+ from M 3+ were determined. The electrostrictive component for the change in the oxidation state for the M 3+/2+ couple was calculated on the basis of the Drude-Nernst equation and by the mean spherical approximation (MSA). The isolated volumes for the formation of M 2+ from M 3+ were compared with the values predicted by theory.

The compounds (trienH 2 )[Mn(H 2 O) 3 X 3 ]X · H 2 O(X = Cl,Br) crystallize at room temperature from equimolar solutions of triethylenediamine and MnX 2 · 4 H 2 O in 3M HX in the orthorhombic space group P2 1 2 1 2 1 with a =6.828( 1), b = 12.128(2), c = 18.367(4) Å, Z = 4 for the chloride, and a = 7.001 (1), b = 12.651 (3), c = 18.885(4) Å, Z = 4 for the bromide, respectively. Both structures contain cations (trienH 2 ) 2+ , complex octahedral anions [Mn(H 2 O) 3 X 3 ] - , isolated halide ions and water molecules. The thermal behavior has been investigated on the basis of conventional thermoanalytical as well as TG-MS techniques. The thermal decomposition proceeeds in three stages, i.e. the dehydration forming (trienH 2 )[MnX 4 ], a phase transition of the tetrahalomanganates(II), and, finally, their decomposition which is influenced by the nature of the atmosphere. The dehydration step is reversible.

Reaction of the chloromethylchlorophosphines R(Cl)P-CH 2 -Cl (R = Cl, tBu, C 6 H 11 , NEt 2 , NPh 2 ) (L) with C 7 H 8 Mo(CO) 4 or (CO) 5 W(Py), (CO) 6 W and (CO 5 W(THF) yields the complexes cis-Mo(CO) 4 L 2 (2a - 2e) or (CO) 5 WL (3a - 3c), respectively, in high yields. The palladium(II) complexes PdCl 2 L 2 (4a - 4c) are obtained on treatment of 1a, 1b and 1e with 1,5-cyclooctadiene palladium(II) chloride or anhydrous palladium(II) chloride in a homogeneous or heterogeneous reaction, respectively. 4a - 4c are formed as a mixture of cis- and trans-isomers. The 13 C { 1 H} NMR and 1 H NMR spectra of 2a - 4c have been analysed, the trans-structure of 4c could be assigned to the predominant isomer. The X-ray structural analysis of 4c (triclinic, space group Pl̅) reveals a trans-square planar coordination at palladium with an antiperiplanar arrangement of the bulky tBu substituents at the phosphorus atoms. Electronic (ƩX i Mo ) and steric ligand parameters (θ) are given for the chloromethylchlorophosphines R(Cl)P-CH 2 -Cl (R = Cl, tBu, C 6 H 11 , NEt 2 , NPh 2 ).

A single-crystal X-ray diffraction study was performed on methylpropylglyoxal bis(amidinohydrazone) (M PGBG) sulphate monohydrate. The bis(amidinohydrazone) dication was found to exist exclusively in the form of the anti-anti isomer, with an all-trans configuration of the glyoxal bis(amidinohydrazone) chain, just as do the free base, the monocation and the dication of glyoxal bis(amidinohydrazone) and the dications of all mono-and dialkylglyoxal bis(amidinohydrazones) so far studied. MPGBG sulphate monohydrate crystallizes in the triclinic space group Pl̅ with unit cell parameters a = 8.860(2), b = 9.195(2), c = 10.788(2) Å, α = 73.71(3), β = 77.59(3), γ = 65.28(3)° and with Z = 2. When the structure is compared with that of propylglyoxal bis(amidinohydrazone) (PGBG) sulphate, an analogous compound that is devoid of the methyl group of MPGBG, a distinct difference can be observed regard­ing the conformation of the propyl side chain. In the MPGBG dication, the propyl group is directed away from the glyoxal bis(amidinohydrazone) chain, whilst in the case of the PGBG dication it is tangled around the glyoxal bis(amidinohydrazone) moiety. Whether this difference results from packing effects and related factors, or whether it is a result of a more fundamental difference between MPGBG and PGBG, remains to be studied. The observed difference may contribute to the biochemical differences between the two compounds.

The tetramethylammonium thioarsenate(III) [Me 4 N] 2 [As 6 S 10 ] (1) has been prepared together with the minor product [Me 4 N] 2 [As 4 S 7 ] (2) by reaction of [Me 4 N]Cl with As 2 S 3 and Na 2 S in acetonitrile at 115 °C. The polymeric anion of 1 consists of adjacent 1 ∞ [As 3 S 5 - ] chains linked together into a 1 ∞ [As 6 S 10 2- ] double chain through planar As 2 S 2 rings involving As atoms of every second constituent ring-shaped As 3 S 6 building unit. A relatively undistorted Ψ-AsS 4 trigonal bipyramidal geometry is observed for the participating As atoms. Individual As 3 S 6 units are linked by bridging AsS 3 pyramids into the zweier single chains 1 ∞ [As 4 S 7 2- ] in 2.

The attempted crystal growth of 1,4-bis(tricyanovinyl)benzene dianion salts, although without success so far, has provided information of general interest. The crystal structures of the related mono and 1,4-bis(tricyanovinyl)benzene derivatives differ considerably in their substituent group twisting angles: The two tricyanovinylbenzenes in split-positions exhibit dihedral angles of only 6° or 11°, whereas the two C 2 (CN) 3 groups of the disubstituted benzene are conrotationally twisted by 48° out of the benzene plane. Density functional calculations with 6 - 311 ++ G** basis sets, however, predict identical values of 32° for both compounds and, therefore, their crystal arrangements are discussed in detail for packingenforced additional interactions. Cyclovoltammetric and ESR/ENDOR-measurements provide information on the redox behaviour, a prerequisite for attempts to crystallize molecular anion salts: The 1,4-disubstituted derivative with a cyclovoltammetrically determined halfwave reduction potential of +.14 V in aprotic THF solution proves to be one of the strongest polycyano-substituted π-acceptors and its radical anion can be selectively generated by T1 metal reduction as confirmed by its ESR/ENDOR spectra.

The reaction of 3.5-diphenyl-1.2-dithiolium chloride with (thio)benzoylhydrazine in the presence of nickel acetate gives bis(thiodibenzoylmethanato)nickel(II). In the presence of zinc acetate 3.5-diphenyl-2-benzoylimino-isothiazole is received instead of the expected metal chelate. Structural data: Bis(thiodibenzoylmethanato)nickel(II), a = 954,9(1); b = 993,5(1); c = 1488,3(1) pm; α = 83,003(4)°; β = 80,541(5)°; γ = 64,011(5)°; space group Pl̅, Z = 2; 3.5-Diphenyl-2-benzoylimino-isothiazole: a = 976,9(1) b = 846,3(2); c = 2126,9(5) pm; β = 93,24(5)°; space group P 2 1 /c; Z = 4.

During the course of synthetic studies on gibberellins, three new derivatives (5, 6 , 10) of C 19 -gibberellin series have been prepared. These derivatives will be used as precursors for the biochemical preparations of plant growth regulating inhibitors.

A probable mechanism of the cleavage reaction of thioacetals by copper(II) sulphate adsorbed on silica gel involves: formation of a chelate between sulphur atoms and copper(II), previously coordinated with hydroxyl groups on the silica surface, and the subsequent hydrolysis promoted by hydroxyl groups on the silica gel surface.

Reaction of tetrachloroauric(III) acid hydrate with dicyclohexylcarbodiimide (dcc) in dichloromethane in the presence of equimolar amounts of triethylamine leads to a complex reaction mixture. One of the components was shown by X-ray crystallography to be [(N, N’, N”-tricyclohexyl)- N”-cyclohexylcarbamoylguanidinium] tetrachloroaurate( III) (1) which contains as a cation the addition product of dcc with the corresponding urea.