Syntheses and Studies of the Extended Metal Atom Chains: from Tri- to Trideca-Nuclear Metal String Complexes, a Great Adventure to Develop the Longest Metal String Complexes
Date Issued
2014
Date
2014
Author(s)
Yang, Ching-Chun
Abstract
This thesis concerns in two aspects: First, to overcome crystal disorder arranged in the trinuclear metal strings as the goal. We modified a methyl group on tridentate ligand, and synthesized their linear trinuclear metal strings. Second, intends to synthesize such very long and develop novel applications EMACs are our research purposes. We synthesized three new mix pyridyl-naphthyridyl-amine ligand, bis(N-5-phenylpyridin-2-yl-2-amino-1,8-naphthyridin-7-yl)amine (H3Ph2N9) , N2-(6-(pyridin-2-ylamino)pyridin-2-yl)-N7-(7-(6-(pyridin-2-ylamino)pyridin- 2-ylamino)-1,8-naphthyridin-2-yl)-1,8-naphthyridine-2,7-diamine (H5tpdnpa) and hexapyridyldinapthridylheptaamine (H7hpdnha), and their EMACs.
Asymmetric tridentate ligand (Hpta) synthesized two trinuclear nickel strings [Ni3(pta)4X2] (X = NCS-(1), CN-(2)), accompanying with the molecular structure arranged disorder problem, which means that can not distinguish between thiazolyl group and pyridyl group in the crystal structure. To overcome this problem, we synthesized a new tridentate ligand (Hmpta) by substituting picolyl group for the pyridyl group, in order to increase asymmetrical differences in both sides. By this strategy, we successfully synthesized two trinuclear nickel strings [Ni3(mpta)4X2] (X = NCS-(3), CN-(4)) in (2,2)-cis arrangement.The conductance and resistance for single molecules of 3 are 1.8 (±0.4) × 10–3 G0 and 7.1 (±1.5) MΩ, respectively, compared to 1.2 (±0.4)×10–3 G0 and 11.1 (±3.9) MΩ for 4. The conductivity of 3 is ca. 57 % higher than that of 4, which is reflected in the different distances between nickel atoms (ca. 2.47 A for 3, and ca. 2.52 A for 4).
Nonanuclear nickel and cobalt string complexes are synthesized with H3Ph2N9 ligand. In nickel system, the electrochemistry of Ni9 complexes displays four redox couples at E1/2(red1) = ＋0.12V, E1/2(red2) = －0.09 V, E1/2(red3) = －0.41 V and E1/2(ox1) = ＋0.94 V, repectively. The magnetic moment of [Ni9(Ph2N9)4Cl2](BF4)3.5Cl0.5 (5) is 4.03 μB (300K) and consistent with terminal nickel(II) ions are high-spin states (S＝1). Unfortunately, we could not get a good quality crystal of [Ni9(Ph2N9)4(NCS)2]4+ (6) for single crystal X-ray diffraction experiment. In cobalt system, the single crystal X-ray diffraction analysis reveal that two-electrons reduced in [Co9(Ph2N9)4Cl2](BF4)2 (7) and [Co9(Ph2N9)4(NCS)2](BF4)1.5Cl0.5 (8), and containing two BF4- as the counter anions in 7, one half BF4- and half Cl- in 8, respectively. The terminal chloride and nitrogen of NCS atoms are collinear with Co9 axis. The whole lengths of molecule are 23.2 A and 27.4 A for 7 and 8, respectively. These are the longest EMAC for cobalt complexes reported to date.
Tridecanickel complex [Ni13(tpdnpa)4Cl2](PF6)2 (9) was obtained by the reaction of anhydrous NiCl2 with the H5tpdnpa ligand in an argon atmosphere employing naphthalene as solvent and ButOK as a base to deprotonate the amine groups. The linear chain of tridecanickel atoms are helically wrapped by four all-syn type tpdnpa5- ligands, and the chloride atoms of the axial ligands are collinear with the tridecanickel axis; the molecular length is about 32 A. Magnetic measurement of [Ni13(tpdnpa)4Cl2]×(PF6)2 (9) reveals that antiferromagnetic interactions between the terminal Ni2+ ion and the central Ni23+ unit. The best fit above 4 K corresponds to: g= 2.3, J12 = J34 = -20.24 cm-1, J23 = -284.22 cm-1, indicative of relatively strong antiferromagnetic couplings between mixed-valence Ni23+ units, and weaker antiferromagnetic couplings between Ni2+ and mixed-valence Ni23+ unit. TGA and solvent cyclic ad/de-sorption measurements revealed a one-step weight loss of solvent molecules and reversible dichloromethane, 1,2-dichloroethane and benzene adsorption/desorption process. The N2 ad/de-sorption measurement reveals a typical Type-IV adsorption curve with an H2 hysteresis loop as defined by the IUPAC classification and is characteristic of mesoporous material. The [Ni13(tpdnpa)4Cl2]×(PF6)2 (9) is not only the longest nickel string up to date, but also the first EMAC using in porous applications.
Heptadecanickel complex [Ni17(hpdnha)4Cl2](PF6)4 (10) was obtained by the reaction of anhydrous NiCl2 with the H7hpdnha ligand in an argon atmosphere employing naphthalene as solvent and ButOK as a base to deprotonate the amine groups. Unfortunately, we can not get a good quality crystal to do X-ray diffraction experiment, but we can find it by MALDI-MASS experiment on peak [M+]= 4343.
Subjects
金屬串
磁性
電化學
導電度
Type
thesis
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