Coordination Chemistry of Pentahalocyclopentadienyls

Abstract

The coordination chemistry of perhalocyclopentadienyl ligands, first developed in the early 1970's as a part of a research program directed towards the synthesis of oxidation-resistant fuel additives, has been revived in the last ten years. This renewed interest stems from the discovery that the coordinated cyclopentadienyl ligand allows multiple functionalizations. Thus, the high versatility of this important class of ligands can be broadened even further, which may be iniportant with regard to industrial applications of metallorenes.

Synthesis, chemical reactivity and electrochemical behaviour of mono- and difluoro metallocenes

“…The product is obtained with a purity > 95%, containing traces of ferrocene and difluoroferrocene as indicated by 1 Under a positive pressure of argon, freshly sublimated monobromoferrocene (300 mg, 1.14 mmol) was dissolved in dry tetrahydrofuran (20 ml) and the resulting yellow solution was cooled to -78 °C. Over a period of 5 minutes n-butyllithium in n-hexane (0.5 ml, 1.25 mmol, 2.5 M) was added, ensuring that the temperature does not exceed -70 °C.…”

“…Halogenated metallocenes (with halogens ranging from Cl to I), on the other hand, are quite readily accessible. [1][2][3] In contrast, nearly nothing is known about the (physicochemical) properties of mono-and difluoroferrocenes. Two different approaches for the synthesis of monofluoroferrocene (1) have been published so far.…”

“…[1][2][3] In contrast, nearly nothing is known about the (physicochemical) properties of mono-and difluoroferrocenes. Two different approaches for the synthesis of monofluoroferrocene (1) have been published so far. In 1971, Hedberg and Rosenberg synthesized monofluoroferrocene by using perchloryl fluoride.…”

“…Especially the halogenated ferrocenes (Fe(C 5 H 5 ) 2 with Cp = (C 5 H 5 )) with chlorine, bromine, and iodine are well studied compounds. [1][2][3] In surprising contrast to this, metallocenes with one or multiple fluorine atoms attached to the Cp ring are not investigated in that extent. Metallocenes containing fluorine atoms can be divided into two classes, i.e.…”

Coordination Chemistry of Perhalogenated Cyclopentadienes and Alkynes, XXIX. The Reaction of Ni(0) and Pt(0) Phosphane Complexes with Trichloroethene, Hexachloro- and Hexabromocyclopentadiene

“…Since on one hand, trichloroethene is a starting material for the synthesis of dichloroethyne, the coordination chemistry of which was studied by us in some detail [14], and since on the other hand the special properties of the pentahalocyclopentadienyl ligand allowed us to develop a fascinating coordination chemistry [15], we found it worthwhile to look at the reac-tions of trichloroethene and hexachloro-and hexabromocyclopentadiene with Ni(0) and Pt(0) phosphane complexes.…”