We report the two-step synthesis of a highly soluble fullerene dimer, both for short reaction times and at the microscale. We apply this reaction scheme to starting materials that contain 15N@C60 and 14N@C60, and we demonstrate how, if applied to highly pure N@C60 in the future, this scheme may be used to produce (14N@C60)2 or (15N@C60)2 dimers in one step, and crucially 14N@C60-15N@C60 dimers in a second step. Such dimers represent isolated electron spin pairs that may be used to demonstrate entanglement between the spins. Additionally, CW EPR spectroscopy of the 15N@C60-C60 dimer in the solid state reveals permanent zero-field splitting (D = 14.6 MHz and E = 0.56 MHz). © 2013 Royal Society of Chemistry.
