J. Lamiot

A new crystalline phase of nitric acid dihydrate.

The crystal structure of a new high-temperature phase of nitric acid dihydrate, HNO(3).2H(2)O, has been determined at 225 K by single-crystal X-ray diffraction. The H atom of the nitric acid is delocalized to one water molecule, leading to an association of equimolar NO(3)(-) and H(5)O(2)(+) ionic groups. The asymmetric unit contains two molecules of HNO(3).2H(2)O. The two independent molecules are related by a pseudo-twofold c axis, by a translation of 0.54 (approximately (1/2)) along b, with a mean atomic distance difference of 0.3 A, except for one H atom of the water molecules (1.5 A), because of their different orientations in the two molecules. The two independent molecules, linked by strong hydrogen bonds, are arranged in layers. These layers are linked by weaker hydrogen bonds oriented approximately along the c axis. A three-dimensional hydrogen-bond network is observed.

Double ortho meta regiocontrolled functionalisation of tricarbonyl-(η6-1-tert-butoxycarbonyl-2,3-dimethylbenzene) chromium; 17O NMR study of saponification-elimination mechanism

Abstract The title compound 1 promotes the attachment of an electrophilic group preferentially to the 2-methyl group while the 3-methyl group reacts slightly. A condensation mechanism of 1 with aldehyde involving a lactonisation step is confirmed by a labelling experiment.

Diastereocontrol of η4-α,β-unsaturated ketone–Fe(CO)3 complexation by an adjacent metal-complexed chiral centre

The reaction of tricarbonyl-[η6-3-(o-methyl- or o-methoxyphenyl)-1-phenylprop-2-en-1-onelchromium with nonacarbonyldi-iron gives specifically one diastereoisomer of the η4-Fe(CO)3–α,β-unsaturated ketone–η6 Cr(CO)3–ortho-substituted arene complex, the relative configuration (RS,SR) of which was unambiguously established by X-ray analysis; the equivalent reaction using the 3-m-methoxyphenylpropenone isomer gives a 1 : 1 mixture of two diastereoisomers.

X-ray Structure of a New Pyrethroid, RU 52259

The X-ray structure of this intermediate compound, tert-butyl a-(tert-butylsulfonyl)-fl-(methoxysulfinyl)-3,3-dimethyl-2-[(3-phenoxybenzyl)oxycarbonyl]_ cyclopropaneprop ionate, shows the configuration of the asymmetric atoms at sites C1, C2 and S1 (C~,C t3 and fl-S) and allows the mechanism of its formation to be established. The bond distances in the molecule are in the expected range.

Tricarbonyl(η6-3-methyl-2-vinylbenzoic acid)chromium

The benzylic deprotonation of tricarbonyl(η6-1-tert-butoxycarbonyl-2,3- dimethylbenzene)chromium occurs preferentially at the ortho position, whereas the meta position is still reactive but to a lesser extent. X-ray study of the title compound, [Cr(CO)3(C10H10O2)], obtained in a very good yield, confirms this result and shows a strong hydrogen bond between neighbouring carboxyl groups. The acid group and the phenyl ring are coplanar and the torsion angle between the phenyl ring and the vinyl group is 61.2°(4).