Terpene Cyclases from Social Amoebae

Genome sequences of social amoebae reveal the presence of terpene cyclases (TCs) in these organisms. Two TCs from Dictyostelium discoideum converted farnesyl diphosphate into (2S,3R,6S,9S)‐(?)‐protoillud‐7‐ene and (3S)‐(+)‐asterisca‐2(9),6‐diene. The enzyme mechanisms and EI‐MS fragmentations of the products were studied by labeling experiments.     

Kaliumheptachlorodioxodimolybdat(V), KMo2O2Cl7

Potassium Heptachlorodioxodimolybdate(V), KMo₂O₂Cl₇ KMo₂O₂Cl₇ was obtained at 400 °C from the reaction of SCl₂ with molybdenum which contained traces of potassium. Its crystal structure is monoclinic, space group C2/c, a = 1094.1, b = 1139.1, c = 1018.0 pm, β = 110.16°, Z = 4. In the Mo₂O₂Cl₇^– ion two coordination octahedra share a common face with three chlorine atoms. The crystal structure can be derived from the CsNiCl₃ type by vacating one third of the Ni and two thirds of the Cs positions. The crystallographic group-subgroup relationship is given.     

Kaliumtetrachlorooxomolybdat(V), KMoOCl4

Potassium Tetrachlorooxomolybdate(V), KMoOCl₄ KMoOCl₄ was obtained at 200 °C in small yield as a side‐product from the reaction of S₂Cl₂ with molybdenum which contained 0.7% of potassium (the main product was MoS₂Cl₃). Attempts to increase the yield by adding stoichiometric amounts of KOH or of KCl + H₂O failed. An attempt to produce KMoOCl₄ by the reduction of MoOCl₄ with KI yielded K₃Mo₂Cl₉ and a small amount of K₂MoOCl₅. The crystal structure of KMoOCl₄ is monoclinic, space group P2₁/c, a = 657,1; b = 901,6; c = 2327,3 pm; β = 92,81°, Z = 8. Square‐pyramidal MoOCl₄^– ions are associated to infinite zigzag chains by Mo…Cl contacts.     

A Soluble C60 Graphite Segment

At the limits of analytical investigation one finds the nanodimensional C₆₀ graphite segment 1 , which, thanks to its long-chain alkyl substituents, is soluble. Monolayers of 1 on graphite can be characterized by scanning tunneling microscopy.     

Structural Diversity in the Solid-State Structures of the Rubidium and Cesium Salts of 2,6-Dimesitylphenylphosphane

A coordination environment reminiscent of a paddle-wheel is exhibited by aryl groups about one of the two cesium ions in CsP(H)Dmp (Dmp=2,6-dimesitylphenyl; structure depicted on the right), which has now been synthesized and is found to exhibit Cs⁺{Cs₂[P(H)Dmp]₃}⁻ contact ion pairs in the solid state. In contrast, the analogous rubidium compound displays a Rb₄P₄ cube as the central structural motif.     

On spherically convex sets and Q-matrices

Let K be a closed spherically convex subset of S^n?1 that is contained in a hemisphere, and x?(K) the radial projection onto S^n?1 of the centroid of K. Then p^Tx?(K)>0 for all p ? K. A specialization of this result to spherical simplices is used to derive a necessary condition for Q-matrices, i.e., matrices for which every corresponding linear complementarity problem has at least one solution.