Ionic fullerene compounds containing negatively charged dimers and coordinatively bound anions

Abstract

The review summarizes the results of investigations of ionic fullerene compounds contain ing negatively charged dimers and fullerene anions coordinated to metalloporphyrins. Fullerene radical anions were found to form diamagnetic singly bonded (C 60 -) 2 and (C 70 -) 2 dimers. Dimerization is reversible and leads to paramagnetic-diamagnetic phase transitions or a decrease in the magnetic moment of the complexes. The temperature, at which dissociation of the (C 60 -) 2 dimers begins, varies from 140 to 320 K; the corresponding temperature for the (C 70 -) 2 dimers varies from 260 to 360 K and higher. We prepared the first doubly bonded (C 60 -) 2 dimer. At 300 K, this dimer exists as a biradical. The fullerene radical anions form Co-C coordination bonds with cobalt(II) porphyrinates. The resulting anions are diamag netic. In some cases, Co-C coordination bonds undergo reversible dissociation, resulting in magnetic transitions from the diamagnetic to the paramagnetic state.

A Two‐Dimensional Organic Metal Based on Fullerene

“…Compound 1 is a fascinating example of a material composed of only light elements (C, H, N) that exhibits a metallic state down to 1.9 K. Salts of fullerene C 60 with a number of different inorganic cations have previously shown metallic or superconducting properties. [6,7] D I + is a small, strong donor or cation that ionizes C 60 and determines its charged state, whereas D II is a large, neutral molecule that defines the crystal packing of the complex. 2D fullerene metals have not yet been obtained, whilst the various possible ways of modifying M x C 60 salts have almost been exhausted.…”

“…[6,7] D I + is a small, strong donor or cation that ionizes C 60 and determines its charged state, whereas D II is a large, neutral molecule that defines the crystal packing of the complex. [6,7] D I + is a small, strong donor or cation that ionizes C 60 and determines its charged state, whereas D II is a large, neutral molecule that defines the crystal packing of the complex.…”

The η2 Complex of Nickel Bis(diphenylphosphanyl)propane with Fullerene: {Ni(dppp)(η2‐C60)}·(Solvent) Obtained by Reduction

“…A shorter 6-6 bond with a length of 1.38 Å (hexagon ring junction) behaves as an olefin unit, and different transitionmetal compounds can coordinate to this bond by η 2 -coordination. Fullerene coordination complexes can be prepared by using zero-valent compounds of platinum, palladium, nickel, chromium, osmium, and some other metals, (Ph 3 P) 2 M·(η 2 -C 2 H 4 ) (M = Pd, Pt), (R 3 P) 4 M (R = Et or Ph, M = Ni, Pd, Pt), and (η 6 -C 6 H 5 CH 3 )Cr(CO) 3 . [5][6][7][8][9][10][11] With an excess of a transition-metal compound, multiple addition to C 60 is possible, which provides the formation of a hexaaddition product, namely, {(Et 3 P) 2 M} 6 C 60 , M = Pd, Pt.…”

“…[17] PtC 60 and PdC 60 polymers can be obtained by the reduction of Pd 2+ and Pd 2+ salts in the presence of fullerenes. [18] The addition {Ni(dppp)(η 2 -C 60 )}·(Solvent) Obtained by Reduction of anionic carbonylates such as Co(CO) 4 -, Mn(CO) 5 -, Re(CO) 5 -, CpFe(CO) 2 -, CpM(CO) 3 -(M = Mo, W) is realized through the reduction of C 60 by carbonylate followed by the η 2 -addition of the M(CO) x · radical to the fullerene anion. [19,20] 2-dianions generated in the C 60 reduction by potassium/1-methylnaphthalene in THF.…”

“…[30] Similarly to the IR spectra, coordination of a transition-metal fragment to C 60 splits the bands of some degenerated Raman active modes as a result of lower C 60 symmetry and shifts the high-frequency C 60 modes to lower frequencies as a result of π back-donation. [30] Symmetry-lowering effects were observed in the IR spectra of σ-bonded coordination cobalt(II) tetraphenylporphyrin-fullerene {Co II porphyrin(C 60 -)} anions [4,31] and in the Raman spectra of some η 2 -coordination complexes: [M(PEt 3 ) 2 ] 6 C 60 [30] and IrCO(η 5 -C 9 H 7 )(η 2 -C 60 ). [32] The increase in electron density on C 60 from π back-donation in the (PR 3 ) 2 M(η 2 -C 60 ) complexes (M = Ni, Pd, Pt) is also justified by electrochemical investigation since all three reductions waves for the fullerenes in these complexes are shifted by 0.32-0.34 V to the cathode region relative to those of C 60 .…”