Ligands Coordinated with Cu(II) Complexes in Rare Anti‐Syn 2,2′‐Dipyridylamine and Acetate‐Bridged Forms: Preparations, Crystal Structures, Hydrogen Bonds and Magnetic Properties

The Hdpa (2,2′‐dipyridylamine) ligand can be bonded with metal ions respectively in the anti‐anti, anti‐syn and syn‐syn form, in which the anti‐syn form is rare in the studies. Interestingly, the Hdpa ligand in the mononuclear copper complex [Cu(Acac) 2 (Hdpa) 2 ], 1 (Acac = Acetylacetone) prepared by this experiment is in the rare anti‐syn form. The six‐coordination of Cu(II) atom with two nitrogen atoms are from Hdpa and four oxygens atoms are from Acac. The Crystallographic data show the monoclinic space group P2(1)/n with a = 8.5285(7)Å, b = 9.6900(8)Å, c = 17.9757(15)Å, β = 99.019(2)° and Z = 2. The Hdpa ligand in the zig‐zag chain copper complex [Cu 2 (μ‐CH 3 CO 2 )(NCS) 2 (Hdpa) 2 ] n , 2 prepared by this experiment is in the usual syn‐syn form. But in the long chain, CH 3 CO 2 − (acetate group) and NCS − (thiocyanate) take turns acting as a bridging group, and the bridging carboxylate ligand is in the rare anti‐syn form. The geometry at each copper(II) ion is best described as a distorted(4 + 1) square‐base pyramid. The Crystallographic data show the monoclinic space group P2(1)/c with a = 10.257(3)Å, b = 15.533(4)Å, c = 18.873(5)Å, β = 101.570(4) ° and Z = 4. The crystal of the complex [Cu(dpk·H 2 O) 2 ](SCN) 2 ·2H 2 O, 3 (dpk = di‐2‐pyridyl ketone) was announced in the recognized literature. It was proved that the H 2 O molecule played the role of the bridging bond in the analogue complex [Cu(dpk·H 2 O) 2 ](X) 2 ·nH 2 O. With the presence of the dpk·H 2 O and thiocyanate SCN −1 groups, the complex 3 constitutes the structure of hydrogen bonds with the 2D network of four different forms, such as OH···O(two forms), OH···N and OH···S. This is a pretty extraordinary phenomenon. The Crystallographic data show the monoclinic space group P2(1)/c with a = 7.9174(6)Å, b = 9.2398(7)Å, c = 9.4321(7)Å, β = 95.462(1)° and Z = 1. Complex 1 and complex 3 are Cu (II) mononuclear. This is indicative of the typical paramagnetic behavior of unpaired electrons. We fit the data of the complex 2 by using the equation for S = 1/2 ferromagnetic /antiferromagnetic systems. The best fit parameters for the data are g = 2.03, α = 4.85, J 1 = −0.93 cm −1 , J 2 = 4.52 cm −1 and R = 1.5 × 10 −5 .