Konarev Dmitri V, Khasanov Salavat S, Batov Mikhail S, Martynov Alexander G, Nefedova Irina V, Gorbunova Yulia G, Otsuka Akihiro, Yamochi Hideki, Kitagawa Hiroshi, Lyubovskaya Rimma N
Institute of Problems of Chemical Physics RAS , Chernogolovka , Moscow Region , 142432 Russia.
Institute of Solid State Physics RAS , Chernogolovka , Moscow Region , 142432 Russia.
Inorg Chem. 2019 Apr 15;58(8):5058-5068. doi: 10.1021/acs.inorgchem.9b00131. Epub 2019 Mar 25.
Reduction of terbium(III) double-decker phthalocyanine, TbPc (1), by sodium fluorenone ketyl in the presence of bis(triphenylphosphoranylidene)ammonium cations yields one-electron-reduced (PPN){Tb(Pc)}·2.5CHCl (2) containing the dianionic Pc macrocycles, whereas a stronger NaCpCo(CO) reductant in the presence of an excess of cryptand yields two-electron-reduced {Cryptand(Na)}{(Pc)Tb(Pc)} (3) containing the Pc radical trianionic macrocycle. Isolated pairs of the {Tb(Pc)} anions are formed in 2, whereas compound 3 has unique 3D packing of the macrocycles with weak π-orbitals overlapping in all three directions. This is the first example of the two-electron-reduced lanthanide double-decker containing Pc radical trianion studied in solid state. Compound 2 manifests single-ion magnet (SIM) behavior with a large effective spin-reversal energy barrier of U = 538 cm in comparison with previously studied (BuN){Tb(Pc)} ( U = 230 cm). Thus, changes in cation size and shape affect the molecular packing of {Tb(Pc)} and increase the spin-reversal energy barrier. At the same time, two-electron-reduced species 3 containing Tb and Pc show no signs of SIM such as hysteresis loop at 1.9 K, and no peaks are observed on the temperature dependencies of in-phase (χ') and out-of-phase (χ″) signals. In contrast to EPR silent 2, both compounds 1 and 3 manifest broad signals from paramagnetic Tb ions. Narrower signals attributed to Pc are of high intensity only in 3. In addition to the absorption bands of Pc in the UV and visible spectral range, compound 3 manifests the lowest energy absorption band in solid-state spectra even in the near IR range at 4700 cm (2130 nm), whereas such bands are not observed in the spectrum of 2. These data show that the reduction of the Pc macrocycles in the lanthanide double-deckers leads to the appearance of new very low-energy new transitions associated with Pc whose energy is the lowest among known reduced metal phthalocyanines.
在双（三苯基磷亚基）铵阳离子存在下，芴酮钠自由基对铽（III）双层酞菁TbPc(1)进行还原，生成含二价阴离子酞菁大环的单电子还原产物(PPN){Tb(Pc)}·2.5CHCl(2)；而在过量穴醚存在下，更强的NaCpCo(CO)还原剂会生成含酞菁自由基三价阴离子大环的双电子还原产物{Cryptand(Na)}{(Pc)Tb(Pc)}(3)。在2中会形成孤立的{Tb(Pc)}阴离子对，而化合物3具有独特的大环三维堆积结构，其在所有三个方向上都有弱的π轨道重叠。这是在固态中研究的含酞菁自由基三价阴离子的双电子还原镧系双层化合物的首个例子。与之前研究的(BuN){Tb(Pc)}(U = 230 cm)相比，化合物2表现出单离子磁体(SIM)行为，其有效自旋反转能垒较大，U = 538 cm。因此，阳离子尺寸和形状的变化会影响{Tb(Pc)}的分子堆积并增加自旋反转能垒。同时，含Tb和Pc的双电子还原产物3在1.9 K时没有表现出SIM的迹象，如磁滞回线，并且在同相(χ')和异相(χ″)信号的温度依赖性上也没有观察到峰值。与EPR沉默的2不同，化合物1和3都表现出来自顺磁性Tb离子的宽信号。仅在3中归因于Pc的较窄信号强度较高。除了酞菁在紫外和可见光谱范围内的吸收带外，化合物3在固态光谱中甚至在近红外范围4700 cm(2130 nm)处表现出最低能量的吸收带，而在2的光谱中未观察到此类带。这些数据表明，镧系双层中酞菁大环的还原导致出现与酞菁相关的新的极低能量新跃迁，其能量在已知的还原金属酞菁中是最低的。
