Expanding the world of endohedral fullerenes--the Tm3N@C2n (39< or =n< or =43) clusterfullerene family

Abstract

A new family of endohedral fullerenes, based on an encaged trithulium nitride (Tm(3)N) cluster, was synthesised, isolated and characterised by HPLC, mass spectrometry, and visible-NIR and FTIR spectroscopy. Tm(3)N clusterfullerenes with cages as small as C(76) and as large as C(88) were prepared and six of them were isolated. Tm(3)N@C(78) is a small clusterfullerene. The two isomers of Tm(3)N@C(80) (I and II) were the most abundant structures in the fullerene soot. Tm(3)N@C(82), Tm(3)N@C(84), and Tm(3)N@C(86) represent a new series of higher clusterfullerenes. All six isolated Tm(3)N clusterfullerenes were classified as large energy-gap structures with optical energy gaps between approximately 1.2 and approximately 1.75 eV. Tm(3)N@C(80) (I) and Tm(3)N@C(80) (II) were assigned to the C(80) cages C(80):7 (I(h)) and C(80):6 (D(5h)). For Tm(3)N@C(78), the analysis pointed to an elliptical carbon cage with C(78):1 (D(3)) or C(78):4 (D(3h)) being the probable structures.