ABSTRACT
The structural characterization of the osmahexaborane 2-carbonyl-2,2-bis(triphenylphosphine)-nido-2-osmahexaborane(9), [Os(B(5)H(9))(C(18)H(15)P)(2)(CO)], (I), a metallaborane analogue of B(6)H(10), confirms the structure proposed from NMR spectroscopy. The structure of the osmadecaborane 6-carbonyl-6,6-bis(triphenylphosphine)-nido-6-osmadecaborane(13), [Os(B(9)H(13))(C(18)H(15)P)(2)(CO)], (IV), is similarly confirmed. The short basal B-B distance of 1.652 (8) A in (I), not bridged by an H atom, mirrors that in the parent hexaborane(10) [1.626 (4) A].
ABSTRACT
In [Pt(dppe)(NO(3))(2)], where dppe is ethylene-1,2-bis(diphenylphosphine) (C(26)H(24)P(2)), the Pt atom is coordinated by the two P atoms and by two O atoms of the two nitrate ions. The molecule has a distorted square-planar geometry, with one of the nitrate groups directed on each side of the plane. The cation in cis-[Pt(dppmO-O,P)(2)](NO(3))(2) x 2H(2)O, where dppmO is bis(diphenylphosphinomethyl)diphenylphosphine oxide (C(25)H(22)OP(2)), comprises two five-membered chelate rings, each dppmO ligand being coordinated to platinum through one P atom and the O atom. The larger P--Pt--P angle of 102.25 (4) degrees is due to steric interactions between the two phenyl groups on each P atom.
ABSTRACT
Dimeric motifs formed by silver(I) carboxylates, illustrated here by the unit Ag2(CF3CO2)2, resemble the well known dimerization of carboxylic acids, i.e. 'H2(RCO2)2', but exhibit greater flexibility, while permitting further elaboration into neutral coordination networks through linkage of the silver centres via ditopic ligands.
ABSTRACT
The oxidative cyclisation of cinnamyl ethers mediated by cerium(IV) ammonium nitrate results in the stereospecific formation of 3,4-trans disubstituted tetrahydrofuran derivatives in moderate to good yields.
Subject(s)
Carrier Proteins/chemistry , Cholesterol Esters/blood , Glycoproteins , Propanolamines/chemical synthesis , Carrier Proteins/antagonists & inhibitors , Carrier Proteins/blood , Cholesterol Ester Transfer Proteins , Crystallography, X-Ray , Humans , In Vitro Techniques , Propanolamines/blood , Propanolamines/chemistry , StereoisomerismABSTRACT
The arene dioxides of five 1-substituted pyrenes have been synthesized using dimethyldioxirane. The diasteroisomeric distribution of the dioxides has been determined. X-ray crystallographic structures of the dioxides have also been obtained. These structures show that for the cis dioxides the molecular structures show a departure from planarity, the extent of which is dependent on the substituent.
Subject(s)
Carcinogens/chemical synthesis , Pyrenes/chemical synthesis , Carcinogens/chemistry , Crystallography, X-Ray , Epoxy Compounds , Magnetic Resonance Spectroscopy , Molecular Structure , Pyrenes/chemistry , Stereoisomerism , Structure-Activity RelationshipABSTRACT
The crystal structures of the adamantane derivatives, 1-acetyl-3-adamantanol, C12H18O2, (4), and 3-hydroxyadamantane-1-carboxylic acid, C11H16O3, (5), have been determined by X-ray diffraction. Both structures show extensive intermolecular hydrogen bonding involving the hydroxyl and acetyl groups in compound (4), and the hydroxyl and carboxyl groups in compound (5).
Subject(s)
Adamantane/analogs & derivatives , Adamantane/chemistry , Crystallization , X-Ray DiffractionABSTRACT
The phototransformations of a few 2,3-diaroylaziridines and 2-aryl-3-aroylaziridines have been studied by steady-state photolysis and product analysis. The formation of various photoproducts could be substantiated by ring opening via C-C bond cleavage (leading to azomethine ylides), intramolecular hydrogen abstraction, and C-N bond cleavage. Isolation of stereospecific 3-pyrroline derivatives from the photoreaction of benzoylaziridines in the presence of DMAD confirms our previous results concerning the azomethine ylides as major transient intermediates, produced under laser pulse photoexcitation. Dimethyl 1-cyclohexyl-2-benzoylpyrrole-3,4-dicarboxylate (25), one of the photoadducts derived from the reaction of 1a and 1b with DMAD undergoes a novel and unusual photorearrangement to give dimethyl 2-(1-benzoylcyclohexyl)pyrrole-3,4-dicarboxylate (27), the structure of which was confirmed through X-ray crystallographic analysis.
ABSTRACT
Both C7H14O3 and C6H14O3Si crystallize as racemates from acetone solution, the former incorporating water of crystallization (C7H14O3.0.5H2O). The crystal structures display extensive intermolecular hydrogen bonding involving the hydroxy and carboxylic acid groups to give polymeric networks.
