Three new families of trimetallic nitride template endohedral metallofullerenes (TNT EMFs), based on cerium, praseodymium, and neodymium clusters, were synthesized by vaporizing packed graphite rods in a conventional Krätschmer-Huffman arc reactor. Each of these families of metallofullerenes was identified and characterized by mass spectroscopy, HPLC, UV/Vis-NIR spectroscopy, and cyclic voltammetry. The mass spectra and HPLC chromatograms show that these larger metallic clusters are preferentially encapsulated by a C(88) cage. When the size of the cluster is increased, the C(96) cage is progressively favored over the predominant C(88) cage. It is also observed that the smaller cages (C(80)-C(86)) almost disappear on going from neodymium to cerium endohedral metallofullerenes. The UV/Vis-NIR spectra and cyclic voltammograms confirm the low HOMO-LUMO gap and reversible electrochemistry of these M(3)N@C(88) metallofullerenes.