Adel Nazzal

Mesomorphic Transition Metal Complexes. 4. Dithiene Complexes of Ni, Pd, and Pt.

Abstract A rational synthesis of transition metal dithiene complexes with mesophorphic properties is reported. In addition to the nickel complexes described earlier, we have now obtained the Pd and Pt congerers. While the Ni and Pt complexes show, depending on the length of the para-n-alkyl chains, smectic or nematic mesophases, the Pd complexes have no mesomorphic properties at all. We suggest that the reason for the absence of a mesophase in the Pd complexes is caused by the formation of dimers.

Mesomorphic Transition Metal Complexes 3. Smectic and Nematic Nickel Dithienes

Abstract The synthesis and characterization of the first nematic transition metal complex and of smectic complexes of the dithiene type are described.

The electrochemistry of [1.1]metallocenophanes: a cyclic voltammetry study of homo-binuclear and hetero-binuclear systems

Abstract The redox chemistry of ferrocene is well known: oxidation to the ferrocenium ion is a highly reversible one-electron step. Several studies on ruthenocene have led to conflicting results, but it is now clear that an electrochemically irreversible two-electron oxidation at comparatively high potential is involved. For [1.1]ferrocenophane, two reversible one-electron oxidations are known to exist, which indicate the absence of significant cooperative interactions between the two ferrocene units of this homo-binuclear compound. For the analogous hetero-binuclear iron/ruthenium system we find a ferrocenecentered reversible one-electron oxidation and a ruthenocene-centered irreversible two-electron oxidation, showing the independence of the two different metallocenes in this system. In contrast to this finding, the two ruthenocenes in [1.1]ruthenocenophane appear to interact strongly: this compound shows a quasi-reversible two-electron oxidation at an unusually low potential. The electronic structure of the d ication of [1.1]ruthenocenophane is uncertain, but independent evidence indicates a mixed valence species with one ruthenocene and one ruthenocene dication.

[1.1]Metallocenophanes of iron and ruthenium: synthesis and characterization of homo-binuclear and hetero-binuclear systems

Abstract The synthesis of 1.1′-bis(6-fulvenyl)ruthenocene has been realized in two different ways, by either adding dilithio ruthenocene to 6-dimethylaminofulvene or by treating the ligand anion fulvenyl cyclopentadienide with the tetrakis-DMSO complex of ruthenium dichloride. Hydride addition to this bis-fulvene produces the 1,1′-bis(cyclopentadienylmethyl)ruthenocene dianion, which can be converted either (with FeCl 2 ) to the mixed Fe/Ru [1,1]metallocenophane or (with RuCl 2 (DMSO) 4 ) to [1.1]ruthenocenophane. The mixed Fe/Ru compound can also be obtained from the dianion of 1,1′-bis(cyclopentadienylmethyl)ferrocene and ruthenium dichloride. Both of the new compounds are crystalline materials, which were characterized by 1 H and 13 C NMR spectra as well as by their electronic absorption and mass spectra.

Bridged ferrocenes: XV. Conformational properties of [1.1]ferrocenophane and some of its bridge- and ring-substituted derivatives☆

Abstract Friedel-Crafts acetylation of [1.1]ferrocenophane has afforded the α- and β-acetyl derivatives, which have been separated and converted into the corresponding ethyl derivatives. The effects of ring and bridge substituents upon the conformational mobility of [1.1]ferrocenophane are discussed in the light of the NMR spectra.

An efficient synthesis of [1,1]ferrocenophane via 1,1′-bis(6-fulvenyl)ferrocene

Abstract [1,1]Ferrocenophane can be prepared by reduction of 1,1′-bis(6-fulvenyl)ferrocene with complex borohydrides to give the dianion of 1,1′-bis(cyclopentadienylmethyl)ferrocene. Reaction of this dianion with ferrous chloride produces the ferrocenophane in good yield.

Smectic and nematic derivatives of tetrathiafulvalene (TTF) and their charge transfer complexes with mesomorphic dithienes

The synthesis and characterization of a smectic and a nematic derivative of the strong electron donor tetrathiafulvalene are described which were found to form mixed crystals with bis-styryl dithiolato metal complexes, which by themselves are smectic or nematic.

Synthesis and characterization of 1,1′-bis(6-fulvenyl)ferrocene

Abstract Two efficient syntheses of the previously unknown 1,1′-bis(6-fulvenyl)ferrocene are described. The first involves the preparation of the fulvenylcyclopentadienide ligand anion, which is converted to the fulvenylferrocene by addition of ferrous chloride. The second converts the known dilithioferrocene directly to the bis(fulvenyl)ferrocene by reaction with 6-dimethylaminofulvene. Both syntheses are high yield procedures. Also described are syntheses of the known mono-fulvenylferrocene (ferrocenylfulvene).