Synthesis of a Structurally Perfect d1 Kagome Lattice Antiferromagnet, (CH3NH3)2NaTi3F12

S = 1 /2 kagome lattice antiferromagnets (KLAFs) have attracted great interest since they are closely associated with the long-sought quantum spin liquid (QSL) state. The realization of S = 1/2 KLAF remains an outstanding challenge and efforts have focused principally on Cu2+, d9 compounds. Herein, the synthesis of the first structurally perfect d1 KLAF, (CH3NH3)2NaTi3F12, is presented. The trivalent oxidation state and the Jahn-Teller distortion of Ti3+ ions are probed by single crystal X-ray diffraction, X- ray photoelectron spectroscopy, and UV-vis-NIR diffuse reflectance. No structural phase transitions can be observed from 1.8 K to 523 K. However, a glass transition can be observed due to the disordered, interlayer CH3NH3+ cations. The Curie-Weiss temperature, θcw= -139.5(7) K, and the lack of long-range ordering in magnetic susceptibility and specific heat imply that this compound is a QSL candidate.