Alfred Gieren

(TMPO)Co(CO)2: synthese und röntgenstrukturanalyse eines planar koordinierten cobalt(I)-komplexes

Abstract The compound (TMPO)Co(CO) 2 was synthesized by the reaction of 2,2,6,6-tetramethylpiperidin-1-oxyl (TMPO) with Co 2 (CO) 8 and characterized by 59 Co NMR, IR and mass spectroscopy, and X-ray structure analysis. In the coordinatively unsaturated 16-electron compound the Co I atom is in a planar coordination with the two carbonyls and an O,N -bonded TMPO ligand.

Dicarbonyl(cyclopentadienyl)mangan-komplexe mit phosphino- und arsino-substituierten schwefeldiimiden als brückenliganden. Kristallstruktur und stereochemie von S{NPtBu2[Mn(CO)2Cp]}2☆

Abstract The phosphino/arsino-substituted sulphur diimides tBu2E′NSNEtBu2 (E = E′ = P (1); E′ = P, E = As (2) and E = E′ = As (3)) add two coordinatively unsaturated complex fragments [CpMn(CO)2] to give binuclear coordination compounds (4–6) which contain the intact sulphur diimide as a bridging ligand 1 . According to the X-ray structure analysis of S{NPtBu2[Mn(CO)2Cp]}2 (4) (and of the isomorphous arsino compound S{NAstBu2[Mn(CO)2Cp]}2 (6)), the crystalline sulphur diimide possesses the cis,trans-configuration. However, the angle at the nitrogen atom of the cis-configured SN double bond in 4 is considerably enlarged (151.3(1)°) as compared to that of the trans-SN double bond (119.8(2)°). The enlarged angle, caused by the very large PtBu2[Mn(CO)2Cp} substituent, gives rise to a significant shortening of both the SN and NP distances on the side of the cis-configurated SN double bond. The angle at the central sulphur atom is found to be 118.4(2)°. The 1H, 13C and 31P NMR spectra of the new complexes 4–6 indicate that the cis/trans configuration of the sulphur diimide skeleton also predominates in solution.

Tris(trimethylsilyl)methyl-polyselenides and -polytellurides. X-Ray structure of (Me3Si)3CTeTeTeC(SiMe3)3

Novel polyselenides and polytellurides have been prepared by means of the stabilizing tris(trimetylsilyl)methyl group; [(Me3Si)3C]2Te3, the first compound containing a three tellurium atom chain, crystallizes as a trans-rotamer with a bonding angle of 103.8(1)° at the central tellurium atom and Te–Te bond distances of 2,710(1)A.

Addition von phosphino- und arsino-substituierten schwefeldiimiden an H2Os3(CO)10: Kristallstruktur und dynamische struktureffekte von H2Os3(CO)10(tBu2PNSNAstBu2). Fragmentierung des NSN-gerüstes in H2Os3(CO)10(tBu2PNSNPtBu2)

Abstract The trinuclear cluster H 2 Os 3 (CO) 10 reacts with phosphino- and arsino-substituted sulphur diimides t Bu 2 E′NSNE t Bu 2 (E, E′=P, As) to give the addition products H 2 Os 3 (CO) 10 ( t Bu 2 E′NSNE′Bu 2 ) ( 1 – 3 ) containing an intact NSN system. In these clusters one of the hydrides is terminal, the other one occupies a bridging position on the metal framework. The X-ray crystal structure analysis of the mixed derivative H 2 Os 3 (CO) 10 ( t Bu 2 PNSNAs′Bu 2 ) ( 2 ) reveals the cis , trans -configurated sulphur diimide ligand to be coordinated equatorially through the phosphorus atom. The variable-temperature 13 C and 1 H NMR spectra exhibit a dynamic phenomenon in solution which is interpreted by a cyclic ligand-site exchange involving the two hydrides as well as one axial and one equatorial carbonyl at the hydrogen-bearing osmium atom. The bis(di-t-butylphosphino) derivative 1 is stable only at low temperatures; above 0°C the compound undergoes fragmentation of the NSN system leading to the cluster HOs 3 (CO) 9 [P t Bu 2 N(H)S].

Umsetzungen von schwefeldiimiden mit dreikernigen osmiumclustern: Synthese, kristallstruktur und stereochemie von (μ-H)Os3(CO)8(μ3-AstBu)[μ(N,As)-NSNAstBu2]

Abstract The arsino-substituted sulphur diimide, S(NAs t Bu 2 ) 2 , reacts with Os 3 (CO) 12 in boiling octane to give the trinuclear cluster (μ-H)Os 3 (CO) 8 (μ 3 -As t Bu)[μ( N , As )-NSNAs t Bu 2 ]. An X-ray crystal structure analysis revealed the molecule to contain an open isosceles Os 3 framework capped by a μ 3 -As t Bu ligand. The outer two osmium atoms are fixed by an NSNAs t Bu 2 unit maintaining the sulphur diimide substructure as a μ 2 ( N , As ) bridge. According to temperature-dependent 13 C NMR measurements, the molecule remains rigid in solution up to 70° C.

A cyclopentabenzopyranone produced by the fungus heterobasidion annosum in dual cultures

Abstract A crystalline compound secreted by hyphae of Heterobasidion annosum in the presence of the antagonistic fungi Radulomyces confluens, Gloeophyllum abietinum, Trametes versicolor or Nectria fuckeliana was isolated. By both spectral and X-ray structure analysis, the compound was identified as 7,8-dihydro-9-hydroxy-5,7,7-trimethylcyclopenta-(g)-2-benzopyran- 1( 6H )-one.

Die struktur von [(η5-Cp)Mo(CO)2(μ-TePh)]2, einem doppelt tellurolato-überbrückten dimolybdän komplex

Abstract The X-ray structure analysis of [(η5-Cp)Mo(CO)2(μ-TePh)]2 revealed a structure which is analogous with the homologous sulphur compound. The asymmetric molecule contains a convoluted Mo2Te2 four-membered ring with Mo-Te distances of 2.785–2.865 A without a metal-metal bond. The distance of 3.24 A suggests a partial bond. The phenyl groups, the Cp rings and pairwise the CO groups are positioned trans with respect to each other taking the metal-chalcogen four-membered ring as reference system.

The Synthesis of Phosphino-, Arsino- and Stibino-Substituted Sulfur Diimide Heterocycles in Transition Metal Complexes

Abstract The reaction of pentacarbonylchromium complexes Cr(CO)5 [tBuECl2] (E = P, As, Sb) with the salt K2SN2 (1:1) leads to the formation of either six- or eight-membered sulfur diimide heterocycles. Coordination compounds such as (E = P, As) and Cr(CO)5[tBuE(NSN)2EtBu] (E = As, Sb) have been obtained, and the X-ray crystallographic structure of has been determined. A comparative structural study of transition metal complexes containing the boat-shaped eight-membered ring tBuAs(NSN)2AStBu as a ligand (L) reveals high flexibility of the ring system. Non-bonding transannular As…As distances between 313 and 396 pm have been observed.

Notes. N-thionitrosamine complexes: substitution reactions of complexes [MCl(C6H4Me-p)(CO)(PPh3)2(SNNMe2)](M = Ru or Os) and the crystal structure of [OsCl(C6H4Me-p)(CO)(PPh3)2(SNNMe2)]

The substitution reactions of [MCl(C6H4Me-p)(CO)(PPh3)2(SNNMe2)](M = Ru or Os) with a variety of ligands (azide, carbon monoxide, 2-xylyl isocyanide, or t-butyl cyanide) are described and rationalized with reference to an X-ray structure analysis of [OsCl(C6H4Me-p)(CO)(PPh3)2(SNNMe2)] which reveals a comparatively short Os–S bond [2.411(2)A] and a long Os–Cl bond [2.476(3)A]. The thionitrosodimethylamine ligand is essentially planar, co-ordinated to osmium with its molecular plane almost perpendicular to the phosphorus–phosphorus vector.

Stereoselektive synthese und struktur von 1-(amino[1s,2s,5r)-2-isopropyl-5-methylcyclohexyl] -(s)-methylferrocen

Zusammenfassung A stereospecific multistage synthesis of 1-amino[(1S,2S,5R-2-isopropyl-5-methylcyclohexyl]-(S)-methyl ferrocene ( 7 ) with the natural (-)-menthone as an educt is reported. The configuration of the product 7 is evaluated by way of an X-ray structure analysis. In addition further analytical data including spectroscopic ones of 7 and its precursors 2 , 4 and 6 are given.