Cubane-Type CuII4 and MnII2MnIII2 Complexes Based on Pyridoxine: A Versatile Ligand for Metal Assembling

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• 作者：Nadia Marino ; Donatella Armentano ; Teresa F. Mastropietro ; Miguel Julve ; Giovanni De Munno ; Jos茅 Mart铆nez-Lillo
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：October 21, 2013
• 年：2013
• 卷：52
• 期：20
• 页码：11934-11943
• 全文大小：435K
• 年卷期：v.52,no.20(October 21, 2013)
• ISSN：1520-510X

文摘

By using Vitamin B₆ in its monodeprotonated pyridoxine form (PN-H) [PN = 3-hydroxy-4,5-bis(hydroxymethyl)-2-methylpyridine], two tetranuclear compounds of formula [Mn₄(PN-H)₄(CH₃CO₂)₃Cl₂]Cl路2CH₃OH路2H₂O (1) and [Cu₄(PN-H)₄Cl₂(H₂O)₂]Cl₂ (2) have been synthesized and magneto-structurally characterized. 1 crystallizes in the triclinic system with space group P1̅ whereas 2 crystallizes in the orthorhombic system with Fdd2 as space group. They exhibit Mn^II₂Mn^III₂ (1) and Cu^II₄ (2) cubane cores containing four monodeprotonated pyridoxine groups simultaneously acting as chelating and bridging ligands (1 and 2), three bridging acetate ligands in the syn-syn conformation (1), and two terminally bound chloride anions (1 and 2) plus two coordinated water molecules (2). The electroneutrality is achieved by the presence of chloride counterions in both compounds. Tri- [Mn(1) and Mn(3)] and divalent [Mn(2) and Mn(4)] manganese centers coexist in 1, all being six-coordinate with distorted Mn(1/3)O₆ and Mn(2/4)O₅Cl octahedral surroundings, respectively, the equatorial Mn鈥揙 bonds being about 0.2 脜 shorter at the former ones. The two crystallographically independent copper(II) ions in 2 are five-coordinate in somewhat distorted CuO₅ [Cu(1)] and CuO₄Cl [Cu(2)] square pyramidal geometries. The values of the intracore metal鈥搈etal separation cover the ranges 3.144(1)鈥?.535(1) (1) and 2.922(6)鈥?.376(1) 脜 (2). The magnetic properties of 1 and 2 were investigated in the temperature range 1.9鈥?00 K, and they correspond to an overall antiferromagnetic behavior with susceptibility maxima at 5.0 (1) and 65.0 K (2). The analysis of the magnetic susceptibility data showed the coexistence of intracore antiferro- and ferromagnetic interactions in the two compounds. Their values compare well with those existing in the literature for the parent systems.