Crystal structure of bis-{()-1-[2-(di-phenyl-phosphan-yl)ferrocen-yl]-()-eth-yl}ammonium bromide di-chloro-methane monosolvate.

During the synthesis of an FeBr complex with the PNP ligand (,,,)-[Fe(CH)(CHNP)] (), single crystals of the di-chloro-methane monosolvate of the Br salt of the protonated ligand H were obtained serendipitously, [Fe(CH)(CHNP)]Br·CHCl. The crystal structure of H·Br·CHCl was determined by single-crystal X-ray diffraction. The mean bond lengths in the ferrocene units are Fe-C = 2.

Halide-Mediated -Deprotonation Reactions Applied to the Synthesis of 1,2- and 1,3-Disubstituted Ferrocene Derivatives.

The -deprotonation of halide-substituted ferrocenes by treatment with lithium tetramethylpiperidide (LiTMP) has been investigated. Iodo-, bromo-, and chloro-substituted ferrocenes were easily deprotonated adjacent to the halide substituents. The synthetic applicability of this reaction was, however, limited by the fact that, depending on the temperature and the degree of halide substitution, scrambling of both iodo and bromo substituents at the ferrocene core took place.

Walphos versus Biferrocene-Based Walphos Analogues in the Asymmetric Hydrogenation of Alkenes and Ketones.

Two representative Walphos analogues with an achiral 2,2″-biferrocenediyl backbone were synthesized. These diphosphine ligands were tested in the rhodium-catalyzed asymmetric hydrogenation of several alkenes and in the ruthenium-catalyzed hydrogenation of two ketones. The results were compared with those previously obtained on using biferrocene ligands with a -symmetric 2,2″-biferrocenediyl backbone as well as with those obtained with Walphos ligands.

Biferrocene-Based Diphosphine Ligands: Synthesis and Application of Walphos Analogues in Asymmetric Hydrogenations.

A total of four biferrocene-based Walphos-type ligands have been synthesized, structurally characterized, and tested in the rhodium-, ruthenium- and iridium-catalyzed hydrogenation of alkenes and ketones. Negishi coupling conditions allowed the biferrocene backbone of these diphosphine ligands to be built up diastereoselectively from the two nonidentical and nonracemic ferrocene fragments ()-1-(,-dimethylamino)ethylferrocene and ()-2-bromoiodoferrocene. The molecular structures of ()-2-bromoiodoferrocene, the coupling product, two ligands, and the two complexes ([PdCl(L)] and [RuCl(-cymene)(L)]PF) were determined by X-ray diffraction.

{(R,S(Fc),S(Fc))-2''-Bromo-2-[1-(dimethyl-amino)-ethyl-κN]-1,1''-biferrocene}trihydridoboron.

The title structure, [Fe(2)(C(5)H(5))(2)(C(14)H(19)BBrN)], contains a chiral and asymmetrically 2,2''-disubstituted biferrocene designed as precursor for enanti-oselective non-C(2)-symmetric biferrocenyldiphosphine catalysts. The mean bond lengths in the biferrocene unit are Fe-C = 2.048 (10) Å and C-C = 1.