High pressure NMR kinetics. 29. Variable-temperature, -pressure, and -frequency oxygen-17 NMR study of water exchange on hexaaquatitanium(III): a limiting associative mechanism?
High pressure NMR kinetics. 29. Variable-temperature, -pressure, and -frequency oxygen-17 NMR study of water exchange on hexaaquatitanium(III): a limiting associative mechanism?
复制标题
高压核磁共振动力学。
DOI：
10.1021/ic00258a026
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发表时间：
1987
影响因子：
4.6
通讯作者：
A. Merbach
中科院分区：
文献类型：
--
作者：
A. Hugi;L. Helm;A. Merbach
在1.4、4.7和8.4 t下，用氧-17 FT-NMR谱法研究了六aquaaquatium （III）上的水交换作为温度（249-369 K）和压力（高达235 MPa，在几个温度下）的函数。0.3 m), H （2.0=3.0 m）和三氟甲烷磺酸盐作为非配位对位。得到k/sub ex/SZY = (1.81 +/- 0.03) × 10V s, H* = 43.4 +/- 0.7 kJ mol, s * = + 1.2 +/- 2.2 jk mol), V0* = -12.1 +/- 0.4 cmT mol, US * = -(1.9 +/- 0.4) × 10 s cmT mol MPa。这是迄今为止在六水离子上的水交换反应中测量到的最负的活化体积，接近Swaddle提出的极限结合a机制的-13.5 cmT mol的值。这些结果与涉及六aquaquatium （III）的复杂生成反应的现有数据一起进行了讨论。
Water exchange on hexaaquatitanium(III) has been studied as a function of temperature (249-369 K) and pressure (up to 235 MPa, at several temperatures) by oxygen-17 FT-NMR spectroscopy at 1.4, 4.7, and 8.4 T. The samples in up to 20% XO-enriched H2O contained TiT (approx. 0.3 m), H (2.0=3.0 m), and trifluoromethanesulfonate as noncoordinating counterion. The following kinetic parameters were obtained: k/sub ex/SZY = (1.81 +/- 0.03) x 10V s , H* = 43.4 +/- 0.7 kJ mol , S* = + 1.2 +/- 2.2 J K mol) , V0* = -12.1 +/- 0.4 cmT mol , and US * = -(1.9 +/- 0.4) x 10 S cmT mol MPa . This volume of activation is the most negative value measured so far for a water-exchange reaction on a hexaaqua ion and is close to the value of -13.5 cmT mol suggested by Swaddle for a limiting association A mechanism. These results are discussed together with available data for complex formation reactions involving hexaaquatitanium(III).