Biphasic behavior of the high-spin-->low-spin relaxation of [Fe(btpa)](PF6)2 in solution (btpa = N,N,N',N'-tetrakis(2-pyridylmethyl)-6,6'-bis(aminomethyl)-2,2'- bipyridine).
Biphasic behavior of the high-spin-->low-spin relaxation of [Fe(btpa)](PF6)2 in solution (btpa = N,N,N',N'-tetrakis(2-pyridylmethyl)-6,6'-bis(aminomethyl)-2,2'- bipyridine).
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[Fe(btpa)](PF6)2 在溶液中高自旋-->低自旋弛豫的双相行为 (btpa = N,N,N,N-四(2-吡啶甲基)-6,6
DOI：
10.1021/ic000656t
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发表时间：
2001
影响因子：
4.6
通讯作者：
A. Hauser
中科院分区：
文献类型：
--
作者：
S. Schenker;P. Stein;J. Wolny;C. Brady;J. McGarvey;H. Toftlund;A. Hauser
研究了Fe（Ⅱ）自旋交叉化合物[Fe（btpa）]（PF_6）_2和[Fe（B（bdpa））]（PF_6）_2在溶液中的光诱导高自旋→低自旋弛豫过程。（2-吡啶甲基）-6，6 '-双B（bdpa）是类似的六齿配体N，N ′-双（苄基）-N，N ′-双用变温激光闪光光解法研究了2-吡啶甲基-6，6 '-双（氨甲基）-2，2'-联吡啶的结构。[Fe（B（bdpa））]（PF 6）2表现出单指数的5 T2-> 1A 1弛豫动力学，而[Fe（btpa）]（PF 6）2表现出非溶剂依赖的双相弛豫动力学。[Fe（btpa）]（PF_6）_2在甲醇中的快速反应过程，其速率常数kHL为2.5 × 10 ~（7）s ~（-1），活化能Ea为1294（26）cm ~（-1），也可归因于~ 5T_2 → ~ 1A_1弛豫。在甲醇中的kHL（295 K）为3.7 × 10（5）s-1和Ea为2297（32）cm-1的慢过程--这是迄今为止在溶液中观察到的Fe（II）自旋交叉络合物的最慢光诱导弛豫过程--被归因于5 T2-> 1A 1弛豫过程与吡啶侧臂内几何重排的耦合。
The light-induced high-spin-->low-spin relaxation for the Fe(II) spin-crossover compounds [Fe(btpa)](PF6)2 and [Fe(b(bdpa))](PF6)2 in solution, where btpa is the potentially octadentate ligand N,N,N',N'-tetrakis(2-pyridylmethyl)-6,6'-bis(aminomethyl)-2,2'-bipyridine and b(bdpa) is the analogous hexadentate ligand N,N'-bis(benzyl)-N,N'-bis(2-pyridylmethyl)-6,6'-bis(aminomethyl)-2,2'- bipyridine, respectively, has been studied by temperature-dependent laser flash photolysis. [Fe(b(bdpa))](PF6)2 shows single-exponential 5T2-->1A1 relaxation kinetics, whereas [Fe(btpa)](PF6)2 exhibits solvent-independent biphasic relaxation kinetics. The fast process of [Fe(btpa)](PF6)2 with a rate constant, kHL, of 2.5 x 10(7) s-1 at 295 K and an activation energy, Ea, of 1294(26) cm-1 in methanol can be assigned to the 5T2-->1A1 relaxation as well. The slow process with a kHL(295 K) of 3.7 x 10(5) s-1 and a Ea of 2297(32) cm-1 in methanol--which is the slowest light-induced relaxation process observed so far for an Fe(II) spin-crossover complex in solution--is assigned to a coupling of the 5T2-->1A1 relaxation process to a geometrical rearrangement within the pendent pyridyl arms.