63Cu NMR study of copper(I) carbonyl complexes with various hydrotris(pyrazolyl)borates:: Correlation between 63Cu chemical shifts and CO stretching vibrations
63Cu NMR study of copper(I) carbonyl complexes with various hydrotris(pyrazolyl)borates:: Correlation between 63Cu chemical shifts and CO stretching vibrations
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DOI：
10.1021/ic970138r
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发表时间：
1998-06-15
影响因子：
4.6
通讯作者：
Moro-oka, Y
中科院分区：
文献类型：
--
作者：
Imai, S;Fujisawa, K;Moro-oka, Y
具有一系列受阻L-R1,L-R2配体的铜(I)配合物（L：氢化三(吡唑基)硼酸盐，R1和R2分别是吡唑环3位和5位的取代基），(LCuCO)-Cu-R1,R2 [R1, R2 = Me, Me (1), i-Pr, i-Pr (2), t-Bu, Me合成了(3)、t-Bu、i-Pr (4)、Ph、i-Pr (5)、Ph、Ph (6)1，并通过1H NMR、IR光谱和元素分析进行了表征。 3和6的分子结构已通过X射线晶体学确定。铜(I)位点的电子结构通过Cu-63 NMR光谱和C=O伸缩振动来表征。在室温下，在甲苯中观察到 (LCuCO)-Cu-R1,R2 配合物的尖锐 Cu-63 NMR 信号。具有烷基取代配体 (1-4) 的铜 (I) 配合物 (1-4) 的 Cu-63 NMR 信号在比苯基衍生物 (5, 6) 低的场中观察到，与铜中心的电子密度相关。这一论点得到了 delta((CU)-C-63) 值和 C=O 伸缩振动之间良好相关性的支持，C=O 伸缩振动是 Cu d 电子向反键 C=O 轨道的回馈程度的敏感指标。
Copper(I) carbonyl complexes with a series of hindered L-R1,L-R2 ligands (L: hydrotris(pyrazolyl)borate, R1 and R2 are substituents at the 3- and 5-positions of the pyrazole ring, respectively), (LCuCO)-Cu-R1,R2 [R1, R2 = Me, Me (1), i-Pr, i-Pr (2), t-Bu, Me (3), t-Bu, i-Pr (4), Ph, i-Pr (5), Ph, Ph (6)1 have been synthesized and characterized by]H NMR and IR spectroscopy and elemental analysis. The molecular structures of 3 and 6 have been determined by X-ray crystallography. The electronic structures of copper(I) sites are characterized by means of Cu-63 NMR spectroscopy and by the C=O stretching vibration. The sharp Cu-63 NMR signals are observed for (LCuCO)-Cu-R1,R2 complexes in toluene at room temperature. The Cu-63 NMR Signals of copper(I) complexes with alkyl-substituted ligands (1-4) are observed in lower field than those of the phenyl derivatives (5, 6) correlating with the electron-density at the copper center. This argument is supported by the good correlation between the delta((CU)-C-63) value and C=O stretching vibration which is a sensitive indicator of the extent of back-donation of the Cu d electrons to the antibonding C=O orbitals.