Steering Single-Electron Metal–Metal Bonds and Hyperfine Coupling between a Transition Metal-Lanthanide Heteronuclear Bimetal Confined in Carbon Cages

• DOI: 10.1021/jacs.3c07686
• Publication Date: 2023-10-03T15:11:31Z
• Authors: Wenhao Xiang; Ziqi Hu; Jinpeng Xin; Huaimin Jin; Zhanxin Jiang; Xinyi Han; Muqing Chen; Yang-Rong Yao; Shangfeng Yang
• Keywords: Heteronuclear molecule; Superatom; Endohedral fullerene; Bimetal; Homonuclear molecule

Metal complexes bearing single-electron metal-metal bonds (SEMBs) exhibit unusual electronic structures evoking strong magnetic coupling, and such can be stabilized in the form of dimetallofullerenes (di-EMFs) which two metals are confined a carbon cage. Up to now, only few di-EMFs containing SEMBs reported, all based on high-symmetry icosahedral (Ih) C80 cage embedding homonuclear rare-earth bimetals, chemical modification Ih-C80 is required stabilize SEMB. Herein, by introducing 3d-block transition metal titanium (Ti) along with 4f-block lanthanum (La) into cage, we synthesized first crystallographically characterized SEMB-containing 3d-4f heteronuclear pristine fullerene cages. Four novel La-Ti were isolated, namely, LaTi@D3h(5)-C78, LaTi@Ih(7)-C80, LaTi@D5h(6)-C80, LaTi@C2v(9)-C82, their molecular unambiguously determined single-crystal X-ray diffraction. Upon increasing size from C78 C82, distance decreases 4.31 3.97 Å, affording fine-tuning bonding hyperfine as evidenced an electron spin resonance (ESR) spectroscopic study. Density functional theory (DFT) calculations confirm existence SEMB four LaTi@C2n di-EMFs, accumulation density between La Ti atoms shifts gradually proximity atom inside center LaTi bimetal C82 due decrease distance. The properties differ apparently La2@C2n counterparts, revealing peculiarity involvement Ti.