Asymmetric distortion of bis(.mu.-oxo)bis(oxotungstate(V)) complexes. Crystal structure of bis(.mu.-oxo)(.mu.-N,N'-(R)-propylenediaminetetraacetato)bis(oxotungstate(V))
Asymmetric distortion of bis(.mu.-oxo)bis(oxotungstate(V)) complexes. Crystal structure of bis(.mu.-oxo)(.mu.-N,N'-(R)-propylenediaminetetraacetato)bis(oxotungstate(V))
复制标题
双(μ-氧)双(氧钨酸(V))络合物的不对称变形。
DOI：
10.1021/ic00326a012
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发表时间：
1990
影响因子：
4.6
通讯作者：
Tasuku Ito
中科院分区：
文献类型：
--
作者：
S. Ikari;Y. Sasaki;Tasuku Ito
Mov 2（O）2（μ-O）2配合物在光学活性配体的配位作用下会发生不对称畸变.比较了Wv 2（O）2（μ-O）2配合物与Mov二聚体的畸变。的不对称失真的程度被发现是较小的W v 2复合物比Mo v 2的，证明了以下三个事实。(i)通过X射线晶体结构分析，确定了新配合物[W2（O）2（μ-O）2（μ-R-pdta）] 2−（R-pdta =（R）-丙二胺-N，N，N '，N'-四乙酸酯（4-））的各种扭转角小于Mo 2配合物的相应扭转角. Ba[W_2（O）_2（μ-O）_2]晶体（μ-R-pdta）] 6H2O（C11 H26 N2 O 18 BaW 2）为三斜晶系，空间群P1，晶胞参数a = 7.625（1）A，B = 11.882（2）A，c = 7.133（1）A，α = 98.623（9）A，β = 94.288（9）B，γ = 116.922（8）Ω，V = 562.2（1）A3，Z = 1。通过使用4895个独特的反射来解析结构，|F 0|>3σ（F0），得到R = 0.036。(ii)W2-R-pdta配合物的圆二色性光谱显示出比Mo 2 -R-pdta配合物的相应峰的幅度小的峰。(iii)W 2 -edta（edta =乙二胺四乙酸盐（4-））的不对称反转（Δ Λ）的动态13 C NMR分析给出k =（2.87±0.06）× 10 2 s −1（25 ° C），ΔH：= 36· ± 2 kJ mol −1，ΔS：= 53 ± 5 J K −1 mol −1。ΔH：小于Mo 2 -edta配合物的反转的Δ H：，表明反转的幅度较小。Wv 2复合物的较高程度的共价特征可以解释观察结果
Mo v 2 (O) 2 (μ-O) 2 complexes are known to be distorted asymmetrically when optically active ligands are coordinated. The distortion of the W v 2 (O) 2 (μ-O) 2 complexes has been compared with that of the Mo v dimers. Extent of the asymmetric distorsion is found to be smaller for the W v 2 complexes than for the Mo v 2 ones, as evidenced by the following three facts. (i) The various torsion angles of the new complex [W 2 (O) 2 (μ-O) 2 (μ-R-pdta)] 2− (R-pdta = (R)-propylenediamine-N,N,N',N'-tetraacetate (4-)) as determined by the X-ray crystal structural analysis are smaller than the corresponding angles of the Mo 2 complex. Crystals of Ba[W 2 (O) 2 (μ-O) 2 (μ-R-pdta)]6H 2 O(C 11 H 26 N 2 O 18 BaW 2 ) are triclinic, space group P1, with a = 7.625 (1) A, b = 11.882 (2) A, c = 7.133 (1) A, α = 98.623 (9)˚, β = 94.288 (9)˚, γ = 116.922 (8)˚, V = 562.2 (1) A 3 , and Z = 1. The structure was solved by use of 4895 unique reflections with |F 0 |>3σ(F 0 ) to give R = 0.036. (ii) Circular dichroism spectra of the W 2 -R-pdta complex show peaks with magnitudes smaller than those of the corresponding peaks of the Mo 2 -R-pdta complex. (iii) Dynamic 13 C NMR analysis of the asymmetric inversion (Δ⇄Λ) of the W 2 -edta (edta = ethylenediaminetetraacetate(4-)) gives k = (2.87±0.06) × 10 2 s −1 (25˚C), ΔH: = 36• ± 2 kJ mol −1 , and ΔS: = 53 ± 5 J K −1 mol −1 . The ΔH : is smaller than the one for the inversion of the Mo 2 -edta complex, suggesting smaller amplitude of the inversion. The higher extent of the covalent character of the W v 2 complexes may account for the observations