Kirkman-Davis Emma, Witkos Faith E, Selmani Veli, Monroe Jeffrey C, Landee Christopher P, Turnbull Mark M, Dawe Louise N, Polson Matthew I J, Wikaira Jan L
Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, MA 01610, USA.
Dalton Trans. 2020 Oct 21;49(39):13693-13703. doi: 10.1039/d0dt02716b. Epub 2020 Sep 30.
A family of pyrazine-bridged, linear chain complexes of Cu(ii) of the formula CuL(HO)(pz) [pz = pyrazine; L = n-methyl-2(1H)-pyridone, n = 3 (1), 5 (2), and 6 (3)] has been prepared. Single-crystal X-ray diffraction shows six-coordinate, pyrazine-bridged chains with trans-pairs of ancillary ligands. The substituted pyridine molecules exist in their pyridone tautomers and are coordinated through the carbonyl oxygen atom. The structure is stabilized by intramolecular hydrogen bonds between the pyridone and water molecule, and via hydrogen bonds between the water molecules and perchlorate ions. 2 undergoes a crystallographic phase transition between C2/c (high temperature phase) and P1[combining macron] (low temperature phase). Powder EPR spectra reveal that all complexes are rhombic, although differences between g and g can only be seen clearly at Q-band. Variable temperature magnetic susceptibility data show antiferromagnetic interactions and the data were fit to the uniform chain model yielding J/k = -9.8, -9.2 and -11 K for 1-3 respectively. Attempts to model an interchain interaction strength indicate that the chains are very well isolated.
已制备出通式为CuL(HO)(pz)的一族吡嗪桥连的线性链状Cu(ii)配合物[pz = 吡嗪；L = n - 甲基 - 2(1H)-吡啶酮，n = 3 (1)、5 (2)和6 (3)]。单晶X射线衍射表明存在六配位的、吡嗪桥连的链，且辅助配体呈反式对。取代的吡啶分子以其吡啶酮互变异构体形式存在，并通过羰基氧原子配位。该结构通过吡啶酮与水分子之间的分子内氢键以及水分子与高氯酸根离子之间的氢键得以稳定。2在C2/c（高温相）和P1[结合长音符号]（低温相）之间发生晶体学相变。粉末EPR光谱表明所有配合物均为菱形，尽管只有在Q波段才能清楚地看到g和g之间的差异。变温磁化率数据显示出反铁磁相互作用，数据分别拟合到均匀链模型，得出1 - 3的J/k = -9.8、-9.2和 -11 K。对链间相互作用强度进行建模的尝试表明这些链彼此隔离得很好。
