Novel 9-Nickelafluorenyl Sandwich Complexes of Nickel(II) and Cobalt(II)

Abstract

lithium was found to react with Ni(II) and Co(II) salts to form noVel complexes in which the Ni or Co central metal atom is bonded to two nickelafluorenyl ligands. The crystal and molecular structures of the products were determined by single-crystal X-ray analysis.Recently there has been considerable interest in the aromatic properties of cyclic π-systems containing heteroatoms, mainly because of their potential ability to act as multielectron ligands. A well-known preparation of metal-cyclopentadienyl complexes involves the reaction of an appropriate cyclopentadienyllithium complex with with a metal salt. 1 Such reactions also can be carried out with heterocyclopentadienyllithium complexes. 2 Although the synthesis of heterofluorenyl-alkali-metal complexes containing main-group elements 3 and transition metals (zirconium) 4 have been reported, they were not employed in the formation of the compounds in which the metal atom is bonded to the heterocyclic ring.Recently we have reported the synthesis of (9-nickelafluorenyl)lithium complexes, 5 novel metallafluorenyl-alkali-metal compounds that contain a transition metal in the five-membered metallacyclic ring.We report here the reactions between metal bromides or acetylacetonates of nickel and cobalt and the (9-nickelafluore-nyl)lithium species 1, in which acetylacetonate or bromide ligands are displaced by the 9-nickelafluorenyl group to form complexes in which the nickel or cobalt atom is bonded to two 9-nickelafluorenyl ligands in a sandwich-type complex.

Crystal structure of tetraaqua[2,4-dichlorophenoxyacetato- κ:O]cobalt(II) hydrate, Co(H2O)4(C8H5Cl2O3)2 · H2O

“…So far, the aromatic multicarboxylate ligands like 1,2-benzenedicarboxylic acid, 1,3-benze nedicarboxylic acid and 1,4-benzenedicarboxylic acid are widely applied to construct the metal-organic frameworks with diverse topology and interesting properties [4][5][6]. On the other hand, the derivatives of imidazole, such as 2,4-dichlorophenoxy acetic acid are important ligands with numerous applications in constructing metal-organic coordination polymers [7]. The crystal structure of the title compound contains a Co(H 2O)4(C8H5Cl2O3)2 complex and one free water molecule in the independent unit.…”

Novel, axially chiral analogues of nickelocene with nickeladibenzofluorenyl ligand

“…In previous papers we described the synthesis of new nickelametallocenes [3] which possessed one nickelaindenyl or nickelafluorenyl ring [4]. More recently we have employed 9-nickelafluorenyllithium [1], in the synthesis of the first analogues of nickelocene and cobaltocene with two nickelafluorenyl rings [5].…”

“…In previous papers we described the synthesis of new nickelametallocenes [3] which possessed one nickelaindenyl or nickelafluorenyl ring [4]. More recently we have employed 9-nickelafluorenyllithium [1], in the synthesis of the first analogues of nickelocene and cobaltocene with two nickelafluorenyl rings [5].In this paper we report the reactions between (1,1 0 -binaphthalene-2,2 0 -diyl)dilithium with nickelocene, pentamethylcyclopentadienylnickel acetylacetonate and with pentamethylcyclopentadienylcobalt acetylacetonate and the influence of the binaphthyl ligand on the formation of metallacycles. …”

Dinickelaferrocene: A Ferrocene Analogue with Two Aromatic Nickeloles Realized by Electron Back‐Donation from Iron

“…[5] Even for more general dimetallametallocenes with two transitionmetal metallole ligands few examples are known. [6] In contrast, metallole ligands with main-group metals, such as Sb, Bi, Ge, Sn, which are generally 6p aromatic systems similar to Cp ligands in ferrocene, have often been used to prepare their corresponding metallametallocenes, for instance II. [4,7] The lack of metallametallocenes with transition-metal metallole ligands is likely due to, besides the shortage of synthetic methods, the essential difference in aromaticity between main-group-metal metalloles and transition-metal metalloles, which ultimately can be traced back to their intrinsically distinct bonding modes.…”

“…[4,7] The lack of metallametallocenes with transition-metal metallole ligands is likely due to, besides the shortage of synthetic methods, the essential difference in aromaticity between main-group-metal metalloles and transition-metal metalloles, which ultimately can be traced back to their intrinsically distinct bonding modes. [4][5][6][7][8][9] A straightforward way to synthesize dimetallaferrocene is to react iron salts, such as FeBr 2 , with their corresponding anionic or dianionic metalloles. [4] Dilithionickelole 1 (Scheme 2), an aromatic dianionic nickelole, was recently realized in high yields in our research group from the reaction of 1,4-dilithio-1,3-diene with Ni(cod) 2 complex.…”