Redox and UV/VIS/NIR spectroscopic properties of tris(pyrazolyl)borato–oxo–molybdenum(V) complexes with naphtholate and related co-ligands
作者:Andrew M. McDonagh、Michael D. Ward、Jon A. McCleverty
DOI:10.1039/b104575j
日期:——
A series of complexes has been prepared in which (Tp*)MoV(O)Cl}+ termini [Tp*
 = tris(3,5-dimethylpyrazolyl)hydroborate] have been coordinated with ligands containing naphtholate binding sites. Mononuclear complexes, in which the sixth ligand is e.g. 1-naphtholate or 2-naphtholate, have been prepared; in addition some dinuclear complexes
were also prepared based on bridging ligands containing either two naphtholate termini, or one naphtholate
terminus and one phenolate terminus. The complexes have been studied by electrochemistry and UV/VIS/NIR spectroelectrochemistry to evaluate how the naphtholate donors affect the properties of the complexes compared
to their known phenolate-based analogues. It was found that mononuclear complexes with phenolate, 1-naphtholate and 2-naphtholate ligands give significantly different electronic spectra in their oxidised [Mo(VI)] forms, with
the characteristic phenolate â Mo(VI) LMCT transition being at much lower energy for the naphtholate complexes
than the phenolate, an observation which is of significance for development of electrochromic near-IR
dyes. In addition, the twist induced in some of the bridging ligands by the bulky naphtholate termini results in substantially decreased metalâmetal electronic interactions compared to the equivalent phenolate-based complexes.
制备了一系列配合物,其中(Tp*)MoV(O)Cl}+末端[Tp*
已与含有萘甲酸酯结合位点的配体配位。单核配合物,其中第六个配体是例如已制备1-萘酚盐或2-萘酚盐;另外还有一些双核配合物
还基于含有两个萘甲酸酯末端或一个萘甲酸酯的桥连配体制备
末端和一个酚盐末端。通过电化学和 UV/VIS/NIR 光谱电化学研究了这些配合物,以评估萘甲酸酯供体如何影响比较的配合物的性质
其已知的基于酚盐的类似物。研究发现,具有酚盐、1-萘酚盐和 2-萘酚盐配体的单核配合物在其氧化的 [Mo(VI)] 形式中给出显着不同的电子光谱,其中
对于萘甲酸盐配合物,特征酚盐 - Mo(VI) LMCT 跃迁的能量要低得多
比酚盐,这一观察对于电致变色近红外的发展具有重要意义
染料。此外,与同等的基于酚盐的配合物相比,大的萘酚盐末端在一些桥配体中引起的扭曲导致金属-金属电子相互作用显着降低。