期刊
CHEMISTRY-A EUROPEAN JOURNAL
卷 15, 期 40, 页码 10620-10633出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.200901126
关键词
aggregation; bridging ligands; phosphane ligands; self-assembly; steric hindrance
资金
- Hungarian Research Fund [OTKAT047321]
The coordination properties of N,N'-bis[4-(4-pyridyl)phenyl]acenaphthenequinonediimine (C) and N,N'-bis[4-(2-pyridyl)phenyl]acenaphthenequinonediimine (L-2) were investigated in self-assembly with palladium diphosphane complexes [Pd(P boolean AND P)(H2O)(2)](OTf)(2) (OTf=triflate) by using various analytical techniques, including multinuclear (H-1, N-15, and P-31) NMR spectroscopy and mass spectrometry (P boolean AND P=dppp, dppf, dppe; dppp=bis(diphenylphosphanyl)propane, dppf=bis(diphenylphosphanyl)ferrocene, and dppe=bis(diphenylphosphanyl)ethane). Beside the expected trimeric and tetrameric species, the interaction of an equimolar mixture of [Pd-(dppp)](2+) ions and L-1 also generates pentameric aggregates. Due to the E/Z isomerism of L-1, a dimeric product was also observed. In all of these species, which correspond to the general formula [Pd(dppp)L-1](n)(OTf)(2n) (n=2-5), the L-1 ligand is coordinated to the Pd center only through the terminal pyridyl groups. Introduction of a second equivalent of the [Pd(dppp)](2+) tecton results in coordination to the internal, sterically more encumbered chelating site and induces enhancement of the higher nuclearity components. The presence of higher-order aggregates (n=5, 6), which were unexpected for the interaction of cis-protected palladium corners with linear ditopic bridging ligands, has been demonstrated both by mass-spectrometric and DOSY NMR spectroscopic analysis. The sequential coordination of the [Pd(dppp)](2+) ion is attributed to the dissimilar steric properties of the two coordination sites. In the self-assembled species formed in a 1:1:1 mixture of [Pd(dppp)](2+)/[Pd(dppe)](2+)/L-1, the sterically more demanding [Pd(dppp)](2+) tectons are attached selectively to the pyridyl groups, whereas the more hindered imino nitrogen atoms coordinate the less bulky dppe complexes, thus resulting in a sterically directed, size-selective sorting of the metal tectons. The propensity of the new ligands to incorporate hydrogen-bonded solvent molecules at the chelating site was confirmed by X-ray diffraction studies.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据