Antiferromagnetic Mixed-Valence Cu(I)鈥揅u(II) Two-Dimensional Coordination Polymers Constructed by Double Oximato Bridged Cu(II) Dimers and CuISCN Based One-Dimensional Anionic Chains

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• 作者：Lakshmi Kanta Das ; Carmen Diaz ; Ashutosh Ghosh
• 刊名：Crystal Growth & Design
• 出版年：2015
• 出版时间：August 5, 2015
• 年：2015
• 卷：15
• 期：8
• 页码：3939-3949
• 全文大小：615K
• ISSN：1528-7505

文摘

One dinuclear Cu(II) complex [Cu₂L²₂(EtOH)_0.5(ClO₄)](ClO₄) (1) has been synthesized by reacting an oxime-based tridentate Schiff base ligand, 3-[2-(diethylamino)ethylimino]butan-2-one oxime (HL²), with Cu^II(ClO₄)₂, whereas the reaction of another similar ligand, 3-[2-(dimethylamino)ethylimino]butan-2-one oxime (HL¹), and this ligand (HL²) with Cu^II(ClO₄)₂ in the presence of NaSCN yielded two rare mixed-valence Cu(I)鈥揅u(II) two-dimensional (2D) coordination polymers, ²_{鈭?/sub>[{(Cu^II2L¹2)}{Cu^I4(渭1,3-SCN)2(渭1,1,3-SCN)4}]n (2) and ²鈭?/sub>[{(Cu^II2L²2)}{Cu^I2(渭1,3-SCN)2(渭1,1,3-SCN)2}]n (3), respectively. The presence of SCN^{鈥?/sup> during the synthesis of the complexes induces reduction of a part of the Cu(II) to Cu(I) giving rise to these two novel mixed-valence 2D coordination polymers 2 and 3. All three complexes have been structurally and magnetically characterized. In complex 1, the square pyramidal Cu(II) atoms are joined by the double oximato bridges. On the other hand, the railroad track-like 2D sheet of 2 and stair-like arrangement of the 2D layer of 3 have been constructed by the connection of one-dimensional (1D) anionic chains ([CuI2(SCN)3]nn鈥?/sup> in 2 and [CuI(SCN)2]nn鈥?/sup> in 3) through the cationic oximato bridged dinuclear units ([CuII2L12]2+ in 2 and [CuII2L22]2+ in 3) via the sulfur atom of the thiocyanato ligand. In both complexes, Cu(I) and thiocyanato ligand form 1D infinite chains, but their different stoichiometry and coordination environments around the copper centers result in different structures. Variable-temperature (2鈥?00 K) magnetic susceptibility measurements show that complexes 1鈥?b>3 exhibit a strong antiferromagnetic interaction between two Cu(II) ions via N,O oximato bridges with J values 鈭?49.6, 鈭?78.7, and 鈭?63.8 cm鈥?, respectively.}}