Syntheses and Studies of the Pentanuclear Heterometallic String Complexes with Binaphthyridylamine Ligand

• Main Authors: Ssu-Chieh Hsu, 許思絜
• Other Authors: Shie-Ming Peng
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/dp9785

碩士 === 國立臺灣大學 === 化學研究所 === 105 === The thesis foucused on extended metal atom chains (EMACs) about pentanuclear heterometallic string complexes with symmetric binaphthyridylamine which contained plentiful electronic properties, metal-metal multiple bond and conductivity. [NiMo2Ni2(bna)4Cl2](PF6)3 (1), [NiMo2Ni2(bna)4(NCS)2](PF6)3 (2) and [NiRu2Ni2(bna)4Cl2](ClO4)3 (3) have been successfully synthesized by controlling proper ratio of Mo2(OAc)4/Ru2(OAc)4Cl and Ni(OAc)24H2O. All these materials have been characterized by Matrix-Assisted Laser Desotption Ionization Time-of-Flight Mass Spectrometer (MALDI-TOF-MS), X-ray Single Crystal of Diffractometer (XRD), Superconducting Quantum Interference Device Magnetometer (SQUID), fourier-transform infrared spectroscopy (FT-IR), Ultraviolet-Visible Spectrometer (UV), and Cyclic voltammetry (CV). The molecular structures reveals that metal ions(NiⅡ-Mo2Ⅳ-Ni2Ⅲ) in complexes are helically wrapped by four deprotonated ligand (bna-) and all coordinated in syn- syn form. Besides,we could observe the distance 2.133(2) and 2.109(2) for complex 1 and 2 between two Mo ions to show quadruple bond. Also, we can observe that remarkably short Ni-Ni distances (2.311 and 2.334 Å) for complex 1 and 2 indicate partial metal–metal bonding, which can be viewed as each complexes containing one mixed-valence [Ni2]3+ unit. Additionally, we found C-N strentching (2070 cm-1) for complex 2 by FT-IR to ensure that axial ligand would be switched to NCS-. For complex 3, we see di nickel unit has longer Ni-N distances to [NiRu2Ni2(tpda)4(NCS)2], so we assign complex 3 has mixed-valence [Ni2]3+ unit. The magnetic measurements show that complex 1 and complex 2 is likely antiferromagnetic compounds (J = -45.6 cm-1 for complex 1 and J = -46.7 cm-1 for complex 2), and we assigned that the terminal nickel ion is high spin state (S = 1) and mixed-valence [Ni2]3+ unit (S = 3/2). The results of cyclic voltammetry indicate the presence three reversible redox couples, so we can predict that [NiM2Ni2(bna)4X2]3+ (M = Mo、Ru, X = Cl、NCS) might be further oxidized to be [NiM2Ni2(bna)4X2]4+ and [NiM2Ni2(bna)4X2]5+ or reduced to be [NiM2Ni2(bna)4X2]2+. The absorption spectra of complex 1, 2 and 3 are shown a broad peak in 500-700 nm regions that we could assign to be intervalence charge transfer (IVCT) system from mixed-valence [Ni2]3+ unit. For complex 3, we don’t observe that signal aroud 1000 nm which belongs [Ru2]5+, so we assign that [Ru2]4+ in complex 3. The values of conductance 1.58(±1.61)x10-5 G0 and resistance 814 MΩ for complex 2 were determined by STM break-juction measurements, and these represent that the first conductance measurements of pentanuclear heterometallic string complexes with binaphthyridylamine ligand.