title: Structures and electronic properties of M2C2 @ C78 (M = Ti, Zr, Hf): a density functional theory study.
abstract: A systematic DFT investigation has been conducted to explore the structures and electronic properties of the metal-carbide endofullerenes M2C2 @ C78 (M = Ti, Zr, Hf) at the PBE/DNP level of theory. The theoretical calculations predicted the following: (i) this series of endofullerenes have the valence states [M4+]2C2(2-) @ C78(6-) (ii) the structure of the [M2C2](6+) cluster encapsulated in the C78(6-) (D3h) cage varies with the increasing of the ionic radius of M4+, i.e., from a linear M-C [triple bond] C-M geometry for M = Ti, through a zigzag geometry for M = Hf to a side-on binding mode for M = Zr; (iii) M2C2 @ C78 (M = Zr, Hf) should display interesting intramolecular dynamic behavior at room temperature, i.e., the encapsulated C2(2-) moiety can rotate freely around the C3-axis of the C78(6-) (D3h) cage; (iv) the [Ti2C2]6+ in the lightest Ti2C2 @ C78 is far more fixed by adopting the linear Ti-C - C-Ti geometry; (v) the order for their ionization potentials is Ti2C2 @ C78 < Hf2C2 @ C78 << Zr2C2 @ C78, whereas their EAs follow the order: Ti2C2 @ C78 < Hf2C2 @ C78 approximately Zr2C2 @ C78. The predicted redox properties of these endofullerenes suggest that Zr2C2 @ C78 is synthetically as approachable as Hf2C2 @ C78.
authors: Departmental of Chemistry, College of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry of Soild Surface and Center for Theoretical Chemistry, Xiamen University, Xiamen 361005, China.
authors: Xin
authors: X
authors: Wu
authors: Xin
authors: X
authors: Lu
authors: Kai
authors: K
authors: Tan
authors: Qianer
authors: Q
authors: Zhang
mesh_terms: D002244:Carbon / Q000737:chemistry*; D004583:Electrons; D037741:Fullerenes / Q000737:chemistry*; D006195:Hafnium / Q000737:chemistry; D007477:Ions; D009682:Magnetic Resonance Spectroscopy; D008670:Metals / Q000737:chemistry; D008968:Molecular Conformation; D015394:Molecular Structure; D036103:Nanotechnology / Q000379:methods*; D010084:Oxidation-Reduction; D012984:Software; D013696:Temperature; D014025:Titanium / Q000737:chemistry; D015032:Zinc / Q000737:chemistry
chemical_list: D037741:Fullerenes; D007477:Ions; D008670:Metals; D002244:Carbon; D014025:Titanium; D015032:Zinc; D006195:Hafnium