Copper(II) Carboxylate Dimers Prepared from Ligands Designed to Form a Robust 蟺路路路蟺 Stacking Synthon: Supramolecular Structures and Molecular Properties

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• 作者：Daniel L. Reger ; Agota Debreczeni ; Mark D. Smith ; Julia Jezierska ; Andrew Ozarowski
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：January 16, 2012
• 年：2012
• 卷：51
• 期：2
• 页码：1068-1083
• 全文大小：1128K
• 年卷期：v.51,no.2(January 16, 2012)
• ISSN：1520-510X

文摘

The reactions of bifunctional carboxylate ligands (1,8-naphthalimido)propanoate, (L_C2^鈥?/b>), (1,8-naphthalimido)ethanoate, (L_C1^鈥?/b>), and (1,8-naphthalimido)benzoate, (L_C4^鈥?/sup>) with Cu₂(O₂CCH₃)₄(H₂O)₂ in methanol or ethanol at room temperature lead to the formation of novel dimeric [Cu₂(L_C2)₄(MeOH)₂] (1), [Cu₂(L_C1)₄(MeOH)₂]路2(CH₂Cl₂) (2), [Cu₂(L_C4)₄(EtOH)₂]路2(CH₂Cl₂) (3) complexes. When the reaction of L_C1^鈥?/b> with Cu₂(O₂CCH₃)₄(H₂O)₂ was carried out at 鈭?0 掳C in the presence of pyridine, [Cu₂(L_C1)₄(py)₄]路2(CH₂Cl₂) (4) was produced. At the core of complexes 1鈥?b>3 lies the square Cu₂(O₂CR)₄ 鈥減addlewheel鈥?secondary building unit, where the two copper centers have a nearly square pyramidal geometry with methanol or ethanol occupying the axial coordination sites. Complex 4 contains a different type of dimeric core generated by two 魏¹-bridging carboxylate ligands. Additionally, two terminal carboxylates and four trans situated pyridine molecules complete the coordination environment of the five-coordinate copper(II) centers. In all four compounds, robust 蟺路路路蟺 stacking interactions of the naphthalimide rings organize the dimeric units into two-dimensional sheets. These two-dimensional networks are organized into a three-dimensional architecture by two different noncovalent interactions: strong 蟺路路路蟺 stacking of the naphthalimide rings (also the pyridine rings for 4) in 1, 3, and 4, and intermolecular hydrogen bonding of the coordinated methanol or ethanol molecules in 1鈥?b>3. Magnetic measurements show that the copper ions in the paddlewheel complexes 1鈥?b>3 are strongly antiferromagnetically coupled with 鈥?i>J values ranging from 255 to 325 cm^鈥?, whereas the copper ions in 4 are only weakly antiferromagnetically coupled. Typical values of the zero-field splitting parameter D were found from EPR studies of 1鈥?b>3and the related known complexes [Cu₂(L_C2)₄(py)₂]路2(CH₂Cl₂)路(CH₃OH), [Cu₂(L_C3)₄(py)₂]路2(CH₂Cl₂) and [Cu₂(L_C3)₄(bipy)]路(CH₃OH)₂路(CH₂Cl₂)_3.37 (L_C3^鈥?/b> = (1,8-naphthalimido)butanoate)), while its abnormal magnitude in [Cu₂(L_C2)₄(bipy)] was qualitatively rationalized by structural analysis and DFT calculations.