单分子磁体-锰配合物的高压红外光谱研究

Pressure-Tuning Infrared Spectral Study on the Single-Molecule-Magnet Manganese Complexes

研究了单分子磁体锰配合物Ⅰ :[Mn1 2 O1 2 (O2 CC6 H4 3 Cl) 1 6 (H2 O) 3(3 Cl C6 H4 CO2 H) ]·(3 Cl C6 H4 CO2 H)和配合物Ⅱ :[Mn1 2 O1 2 (O2 CCH2 Br) 1 6 (H2 O) 4]·4 (CH2 Cl2 )的高压红外光谱 ,两者不同的压力诱导相转变的压力 (配合物Ⅰ :2 5～ 2 9kbar,配合物Ⅱ :2 9～ 35kbar)被观察到 ,两者均为二级压力诱导相转变。认为在压力诱导相转变时 ,也发生了配合物高自旋向低态自旋态的转变。配合物Ⅰ的平均压力灵敏度不同于通常情况 ,它在低压相区的平均压力灵敏度 (0 19cm- 1 ·kbar- 1 )比高压相区 (0 2 9cm- 1 ·kbar- 1 )低。而配合物Ⅱ与通常情况相似 ,在低压相区平均压力灵敏度 (0 34cm- 1 ·kbar- 1 )比高压相区 (0 2 3cm- 1 ·kbar- 1 )为高 ,即在高压相区的可压缩性比低压相区小。

The infrared spectra (IR) of single-molecule-magnet manganese Complexes [Mn-12 O-12 (O2CC6H3-3-Cl)(16) (H2O)(3) (Cl-3-C-6 H4CO2H)](.)(3-Cl-C6H4CO2H) (I) and [Mn-12 O-12 (O2CCH2Br)(16) (H2O)(4)](.)4(CH2Cl2) (II) were studied at high external pressure. The different pressure-induced phase transition pressures were observed for both complexes (complex I, 25-29 kbar) and (complex II, 29-35 kbar). Both were second-order pressure-induced phase transition. The possible changes from higher spin to lower spin happened near the phase transition pressure following the changes of their structures when undergoing the high pressures. The average value of pressure sensitivities in the low-pressure phase is unusually smaller (0.19 cm(-1) (.) kbar(-1)) than in the high-pressure phase (0.29 cm(-1) (.) kbar(-1)) in the complex I. On the contrary, the average value of the pressure sensitivities in the low-pressure phase is higher (0.34 cm(-1) (.) kbar(-1)) than in the high-pressure phase (0.23 cm(-1) (.) kbar(-1)) in the complex II as usually, which means that the possibility of compression is lower in the high-pressure phase than in the low-pressure phase.