HE-I VALENCE PHOTOELECTRON-SPECTRA OF OXOMOLYBDENUM(V) COMPLEXES CONTAINING DIOLATO OR ALKOXIDE LIGANDS
HE-I VALENCE PHOTOELECTRON-SPECTRA OF OXOMOLYBDENUM(V) COMPLEXES CONTAINING DIOLATO OR ALKOXIDE LIGANDS
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DOI：
10.1016/s0277-5387(00)84009-7
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发表时间：
1990-01-01
期刊：
影响因子：
2.6
通讯作者：
ENEMARK, JH
中科院分区：
文献类型：
--
作者：
CHANG, CSJ;RAICHAUDHURI, A;ENEMARK, JH
报道了几种通式为LMoO[O-(CH₂)ₙ -O]和LMoO(OR)₂（L = 氢三（3,5 - 二甲基 - 1 - 吡唑基）硼酸盐；n = 2 - 4；R = 甲基、乙基、正丙基）的一氧钼（V）化合物的He I价光电子能谱（PES）。光谱表明，在这些二醇基配合物中，金属 - 螯合环的大小对最高占据分子轨道（HOMO）电离有显著影响。随着二醇基配合物中螯合环尺寸的增加，HOMO向更低的电离能移动（约0.21 - 0.24 eV）。二醇基配合物的HOMO电离能比具有相同碳原子数的类似开链双烷氧基配合物更高。在每个烷氧基上增加一个CH₂单元时，无约束的双烷氧基配合物的HOMO相关电离势的移动要小得多（≤0.11 eV）。这些气相结果与在乙腈溶液中电化学观察到的结果相似，即随着CH₂基团数量的增加，二醇基和双烷氧基配合物都更容易被氧化，这从它们的半波电位可以看出。在烷氧基链上添加CH₂残基时，烷氧基官能团中氧原子的pπ轨道电离也向更低的电离能移动（约0.12 eV）。
The He I valence photoelectron spectra (PES) are reported for several monooxomolybdenum(V) compounds with the general formula of LMoO[O-(CH2)n-O] and LMoO(OR)2 (L = hydrotris(3,5-dimethyl-1-pyrazolyl)borate; n = 2-4; R = Me, Et, nPr). The spectra show that the size of the metal-chelate ring in these diolato complexes has a substantial effect on the HOMO ionization. As the chelate ring size in the diolato complexes increases, the HOMO shifts (ca 0.21-0.24 eV) to lower ionization energy. The diolato complexes have their HOMO''s at a higher ionization energy than analogous open chain bis-alkoxide complexes possessing the same number of carbon atoms. The unconstrained bis-alkoxide complexes show much smaller shifts (.ltoreq. 0.11 eV) in the ionization potential associated with the HOMO upon the addition of a CH2 unit to each alkoxide group. These gas-phase results are similar to the results observed by electrochemistry in acetonitrile solution, where both the diolato and bis-alkoxide complexes become easier to oxidize upon increasing the number of CH2 groups, as indicated by their half-wave potentials. The p.pi. orbital ionizations of the oxygen atoms in the alkoxide functions are also shifted (ca 0.12 eV) to lower ionization energy upon adding CH2 residues to the alkoxide chain.