Superconducting alkali metal fullerides: development of a versatile solution-phase route from soluble M3C60 precursors

Discrete Fulleride Anions and Fullerenium Cations

“…144 Mn(Cp*) 2 121 and Cr(benzene) 2 145 are also suitable for the synthesis of (-1) salts. Reduced metallocene salts such as [Na]-[Mn(Cp*) 2 ] have been used to synthesize THF-solvated alkali metal salts of [60]fullerides in the (-1) 146 and (-3) 147 states. The strongly reducing metal carbonyl complexes Co(CO) 4 -and Fe(CO) 4 -have also been used to reduce C 60 148,149 whereas Mn(CO) 5 -forms an η 2 -C 60 complex.…”

Synthesis of face-centred cubic Cs3C60in THF

“…The disorder (Raman linewidth) and reduced unit cell dimensions could be possible explanations for the inferior superconducting properties of the materials prepared using Cs[Mn(Cp*) 2 ] as a reducing agent in THF. Further optimisation of the proposed synthetic procedure is required to produce Cs 3 C 60 materials 15 with improved superconducting properties, but the present work demonstrates that control of the redox behaviour of the reducing agents reduces contamination by other C 60 charge states. Cs3C60 samples 1 (blue stars) and 2 (red stars).…”

“…Solution chemistry methods have been an important source of novel alkali-metal fullerides and proved especially advantageous for the synthesis of ternary phases or sodium intercalated compounds where better control over stoichiometry and 15 homogeneity of the product is required. [1][2][3][4][5][6] The viability of these methods was heralded by the successful synthesis of the long-sought after highly-expanded Cs 3 C 60 fulleride which surprisingly, depending on the synthesis conditions, adopts two polymorphic structures which become superconducting under pressure.…”

“…Annealing of the as-made material at 350 o C was required in order to obtain high quality solvent-free crystalline material (Sample 1) suitable for synchrotron X-ray powder diffraction studies. 15 Synthesis at twice this scale was also undertaken (Experimental section). The reaction itself proceeds in exactly the same fashion as its predecessor, first leading to a red solution and then on precipitation to a red-brown powder, which quickly turns black upon loss of the solvent.…”

“…subsequently reduced to 20 ml. The Cs 3 C 60 ·xTHF material was precipitated from the solution by the slow addition of dry hexane (20 ml The reaction protocol was carried out as described above by scaling up the amount 15 of reagents and solvents. The amount of the as made product was 171.5 mg.…”