The structure of 2R-(3′S-benzyloxy-5′S-hydroxy-2′R-hydroxymethyl-1′-oxacyclohexan-6′S-yl)-propionic acid-1,5′-lactone,C16H20O5

The title compound is C₁₆H₂₀O₅, MW=292.3, orthorhombic,P2₁2₁2₁,a=9.741(2),b=29.391(7),c=5.354(1) Å from diffractometer measurements,V=1532.8 ų,Z=4,D _c =1.267 g cm^?3,D _o =1.271 g cm^?3 (ether/1,1,2,2-tetrabromoethane), λ(Mo Kα)=0.71069 Å,F(000)=624,μ=1.02 cm^?1, crystal dimensions 0.23×0.23×0.40 mm,R=0.049 for 1164 observed reflections. The molecule contains a possibly significant asymmetric ether linkage between the oxacyclohexane ring and the highly anisotropic benzyl ring. The packing consists of zigzagged chains parallel to thea-axis formed by hydrogen bonds. The chains are separated by van der Waals contacts.     

Cone angle radial profiles

Various methodologies have been reported in the literature for the evaluation of the size of a ligand or organic functional group, with the Tolman cone angle methodology proving to be most popular in inorganic chemistry. A procedure to extend the Tolman concept to the measurement of a ligand size, as a profile over a radial distance from the metal (apex), has been developed. The representation of the Tolman cone angle as a function of distance from the metal is termed a cone angle radial profile (CARP). CARPs for PH₃, PMe₃, PEt₃ and PPh₃ have been determined and are described. CARPs for molecules containing the constrained phosphite ligands P(OCH₂)₃CMe, as determined in actual structures (Cambridge Structural Database), have also been evaluated and indicate the invariant shape of the ligand in the different metal environments. The influence of the choice of the H atom van der Waals radius in steric measurements is also discussed.     

One sided ideals and Carlson's Theorem

Using left ideals, right ideals, and the smallest two sided ideal in a compact right topological semigroup, we derive an extension of the Main Lemma to Carlson's Theorem. This extension involves an infinite sequence of variable words over a finite alphabet, some of which are required to have the variable as the first letter and others of which are required to have the variable as the last letter.

     

Microbial control of hydrogen sulfide production in a porous medium

Applied Biochemistry and Biotechnology - The ability of a sulfide- and glutaraldehyde-tolerant strain ofThiobacillus denitrificans (strain F) to control sulfide production in an experimental system...     

Reactions of transition metal σ-acetylide complexes: III. Synthesis of some aryldiazovinylidene and cycloheptatrienylvinylidene complexes. X-ray structures of [Ru(CCPhNNC6H3Me2-3,4)(PPh3)2(η-C5H5)][BF4] · 0.67CH2Cl2 and [Ru{CCPh(C7H7)}(DPPE)(η-C5H5)][PF6] · 0.63CH2Cl2

Addition of arenediazonium or tropylium salts to Ru(C₂Ph)(L)₂(η-C₅H₅) (L₂ = (PPh₃)₂ or DPPE) gives the corresponding cationic aryldiazovinylidene and cycloheptatrienylvinylidene complexes, respectively; the X-ray structures of the title complexes confirm the presence of the new ligands. The RuC and CC distances are 1.823(9) and 1.34(1) Å for the aryldiazo complex, and 1.848(9) and 1.32(1) Å for the cycloheptatrienyl derivative.