Synthesis, Crystal Structure, and Magnetic Characterization of the Three-Dimensional Compound [Co2(cbut)(H2O)3]n (H4cbut = 1,2,3,4-Cyclobu

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• 作者：Pau D铆az-Gallifa ; Oscar Fabelo ; Jorge Pas谩n ; Laura Ca帽adillas-Delgado ; Juan Rodr铆guez-Carvajal ; Francesc Lloret ; Miguel Julve ; Catalina Ruiz-P茅rez
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：June 2, 2014
• 年：2014
• 卷：53
• 期：11
• 页码：5674-5683
• 全文大小：521K
• 年卷期：v.53,no.11(June 2, 2014)
• ISSN：1520-510X

文摘

A novel cobalt(II) complex of formula [Co₂(cbut)(H₂O)₃]_n (1) (H₄cbut = 1,2,3,4-cyclobutanetetracarboxylic acid) has been synthesized under hydrothermal conditions and its crystal structure has been determined by means of synchrotron radiation and neutron powder diffraction. The crystal structure of 1 consists of layers of cobalt(II) ions extending in the bc-plane which are pillared along the crystallographic a-axis through the skeleton of the cbut^{4鈥?/sup> ligand. Three crystallographically independent cobalt(II) ions [Co(1), Co(2), and Co(3)] occur in 1. They are all six-coordinate with four carboxylate-oxygens [Co(1)鈥揅o(3)] and two cis-[Co(1)] or trans-water molecules [Co(2) and Co(3)] building distorted octahedral surroundings. Regular alternating double oxo(carboxylate) [between Co(1) and Co(1a)] and oxo(carboxylate) plus one aqua and a syn鈥?i>syn carboxylate bridges [between Co(1) and Co(2)] occur along the crystallographic b-axis, the values of the cobalt鈥揷obalt separation being 3.1259(8) and 3.1555(6) 脜, respectively. These chains are connected to the Co(3) atoms through the OCO carboxylate along the [01虆1] direction leading to the organic鈥搃norganic bc-layers with Co(1)鈥揙CO_{(anti鈥?i>syn)}鈥揅o(3) and Co(2)鈥揙CO_{(anti鈥?i>anti)}鈥揅o(3) distances of 5.750(2) and 4.872(1) 脜. The shortest interlayer cobalt鈥揷obalt separation through the cbut4鈥?/sup> skeleton along the crystallographic a-axis is 7.028(2) 脜. Variable-temperature magnetic susceptibility measurements show the occurrence of antiferromagnetic ordering with a N茅el temperature of 5.0 K, followed by a field-induced ferromagnetic transition under applied dc fields larger than 1500 Oe. The magnetic structure of 1 has been elucidated at low temperatures in zero field by neutron powder diffraction measurements and was found to be formed by ferromagnetic chains running along the b-axis which are antiferromagnetically coupled with the Co(3) ions through the c-axis giving rise to noncompensated magnetic moments within each bc-layer (ferrimagnetic plane). The occurrence of an antitranslation operation between these layers produces a weak interlayer antiferromagnetic coupling along the a-axis which is overcome by dc fields greater than 1500 Oe resulting in a phase transition toward a ferromagnetic state (metamagnetic behavior).}