Gilbert G. A. Balavoine

A Novel and Perfectly Aligned Crystal of a Ferrocenyl Chromophore Displaying High Quadratic Nonlinear Optical Bulk Efficiency

The highest nonlinear optical bulk efficiency for a 2-(4-nitrophenyl)ethenylferrocene (140 times that of urea) has been achieved for E-4 owing to a favourable noncentrosymmetrical packing in which all molecules are perfectly aligned (P1 space group).

HIGHLY ENANTIOSELECTIVE ONE-POT SYNTHESIS OF CHIRAL TRI- AND TETRASUBSTITUTED FERROCENES FROM 1,1'-FERROCENEDICARBALDEHYDE

Exclusively planar chirality is exhibited by the ferrocenes obtained in a highly enantioselective synthesis in which a chiral aminoamide acts as a temporary protecting/directing group. This method was used to obtain an enantiomerically pure tetrasubstituted ferrocene, which was transformed into the first C2 -symmetric disubstituted ferrocenophane [Eq. (1)].

Mono and difunctionalisation of chiral ferrocenyl bis-acetals. X-Ray crystal structure of bis-1,1′-[(2S, 4S)-(hydroxymethyl)-2-dioxane1,3]-ferrocene

Abstract The chiral 1,1′-bis-acetals, bis-1,1′-[(2S, 4S)-(hydroxymethyl)-2-dioxane1,3]-ferrocene (3) and 1,1′-bis-1,1′-[(2S, 4S)-(methoxymethyl)-2-dioxane1,3]-ferrocene (4) were synthesized. (3) was crystallographically characterised. The ortholithiation of (4) was studied in various conditions. Fair yields of monosubstituted compounds could be obtained with a complete regioselectivity in favor of the 2 position but the diastereoselectivities were moderate (up to 35%). Some disubstituted compounds can be isolated but in low yields (up to 8%). The regioselectivity is complete in favor of the 2,2′-disubstituted isomer. Only the diastereoisomer with two opposite planar chiralities is observed.

Complexes of new chiral terpyridyl ligands. Synthesis and characterization of their ruthenium(II) and rhodium(III) complexes

Enantiomerically pure, chiral terpyridyl-type ligands L1 (‘dipineno’-[5,6∶5″,6″]-fused 2,2′∶6′,2″-terpyridine) and L2 (‘dipineno’-[4,5∶4″,5″]-fused 2,2′∶6′,2″-terpyridine) have been synthesized in high yields starting from 2,6-diacetylpyridine and enantiopure α-pinene. Complexes of L1 and L2 with RhIII and RuII have been prepared and studied spectroscopically. The complexes [Ru(L)2][PF6]2 (Lxa0=xa0L1 or L2) were obtained in high yields using microwave heating in ethylene glycol as solvent. The rhodium(III) and ruthenium(II) complexes of L1 and L2 have a helically distorted terpyridyl moiety, as shown by the considerable optical activity in the ligand centered and metal to ligand charge transfer transitions. Crystal structures of [Rh(L1)Cl3] and [Ru(L1)Cl3] show a considerable out of plane distortion of the terpyridyl moiety, whereas free L2 and [Ru(trpy)(L2)][PF6]2 have a more planar arrangement of the pyridyl units.

Asymmetric epoxidation of unfunctionalized alkenes using chiral borates

Abstract A new system for asymmetric epoxidation of various unfunctionalized alkenes using a chiral borate and an alkyl hydroperoxide is described. The highest enantioselectivity (51% ee) is obtained for trans-stilbene.

Ruthenium bis(bipyridine) sulfoxide complexes: new catalysts for alkene epoxidation

The ruthenium bis(bipyridine) sulfoxide complexes Ru-1 and Ru-2 exhibit high catalytic activity for epoxidation of unfunctionalized olefins in the presence of [bis(acetoxy)iodo]benzene; with the chiral catalyst, Ru-2, asymmetric induction up to 94% was observed for beta-methylstyrene.

Synthesis and characterization of two ruthenium(II) heteroleptic complexes of annelated derivatives of 2,2′-bipyridine

The synthesis and characterization of two annelated 2,2′-bipyridine molecules (L) and of the corresponding ruthenium(II) heteroleptic complexes, [Ru(bpy)2(L)][PF6]2 are described. The ligands L bear a terbutoxypropyl chain substituent at position 2. We discovered that under basic conditions condensation between an enolisable ketone and an α,β-unsaturated ketone gives exclusively the 1,2-addition isomers with good yields. In contrast to 2,2′-bipyridine, the annelated ligands L show fluorescence emission, probably due to the rigidity of the molecules. Spectroscopic and photophysical results of the heteroleptic complexes at room temperature and at 77 K are similar to the reference complex, [Ru(bpy)3]2+, except for less intense emission quantum yields and lifetimes at room temperature. This behaviour is due to the presence of a substituent and its position adjacent to the nitrogen of the annelated ligands engaged in the coordination, rather than to the rigidity of these ligands. As shown by the crystallographic data, this substituent induces a lengthening of the adjacent Ru–N bond (2.16 A as compared to 2.05 A for the other Ru–N bonds). As a result, the octahedral structure of the heteroleptic complexes is distorted and the probability of nonradiative processes is thus favoured. Synthese et caracte′risation de deux complexes he′te′roleptiques de ruthe′nium(II) de de′rive′s annele′s de la 2,2′-bipyridine. Nous pre′sentons ici la synthese et la caracte′risation de deux nouveaux ligands annele′s (L) de′rive′s de la 2,2-bipyridine, ainsi que de deux complexes he′te′roleptiques de ruthe′nium(II) correspondants, [Ru(bpy)2(L)][PF6]2. Les ligands L comportent comme substituant en position 2 une chaine terbutoxypropyle. Nous avons de′couvert que la condensation en milieu basique entre une ce′tone e′nolisable et une ce′tone α,β insature′e donne exclusivement les isomeres de laddition 1,2 avec de bons rendements. Contrairement a la 2,2′-bipyridine, les ligands annele′s e′tudie′s ici pre′sentent une e′mission de fluorescence probablement due a la rigidite′ des mole′cules. Les re′sultats spectroscopiques et photophysiques des complexes he′te′roleptiques a tempe′rature ambiante et a 77 K sont similaires a ceux du complexe de re′fe′rence, [Ru(bpy)3]2+, avec toutefois un rendement quantique et une dure′e de vie de luminescence beaucoup plus faibles que ce dernier a tempe′rature ambiante. Ce comportement est plus du a lexistence dun substituant et a sa position adjacente a un azote des ligands annele′s engage′s dans la coordination, qua la rigidite′ de ces ligands. Comme le montrent les donne′es cristallographiques, ce substituant provoque lallongement de la liaison Ru–N adjacente (2,16 A contre 2,05 A pour les autres liaisons Ru–N). De ce fait, la structure octae′drique des complexes he′te′roleptiques est distordue, ce qui favorise les processus de de′sactivation non-radiatifs.

New ruthenium( II ) heteroleptic complexes containing the 4-(2-pyridyl)pyrimidine ligand with amine and amino acid substituents

New 4-(2-pyridyl)pyrimidines (L) have been synthesized in high yields by condensing enaminones with the appropriate carboxamidine or guanidine under basic conditions. These asymmetric bidentate diimine ligands coming from a one-step functionalization of amine and amino acid groups were complexed to ruthenium to obtain new heteroleptic complexes of type [Ru(bpy)2(L)]2+. The ligands and complexes have been characterized by usual analytical methods, and the crystallographic study of one complex has been performed. Their spectroscopic and electrochemical properties have been investigated. ZINDO Calculations show that in the MLCT excited state the electron is mainly localized on the pyridylpyrimidine ligand. On the basis of electrochemical data, the first reduction potential of the complexes has been assigned to the redox couple involving this ligand.