Exchange Coupling Mediated by N–H···Cl Hydrogen Bonds: Experimental and Theoretical Study of the Frustrated Magnetic System in Bis(o-phenylenediamine)nickel(II) Chloride

The title compound crystallizes in the monoclinic P21/c space group with a = 11.2470(3) Å, b = 5.9034(2) Å, c = 12.0886(3) Å, β = 115.143(1)°, and V = 726.58(4) Å3 and consists of discrete monomeric NiCl2(o-phenylendiamine)2 molecules. Each o-phen ligand coordinates in a bidentate mode with the chloride ions occupying trans positions in the resulting tetragonally distorted octahedral coordination sphere. Two discrete sets of N–H···Cl hydrogen bonds link the octahedral molecules into a two-dimensional network, with type 1 interactions linking adjacent monomers along the c axis and type 2 interactions linking monomers along the diagonals in the bc plane. Analysis of the magnetic data reveals the existence of weak antiferromagnetic coupling within the layers via these hydrogen bonds, in addition to the presence of zero field splitting, with the best fit obtained for a 1d antiferromagnetic model with g = 2.0917(7), J/k = −2.11(4) K [J = −1.47(3) cm–1], and D = 1.05(3) cm–1 [β = D/|J| = 0.72(6)] for the model with D > 0 and g = 2.0911(6), J/k = −2.26(1) K [J = −1.57(1) cm–1], and D = −0.86(1) cm–1 [β = D/|J| = 0.55(6)] for the model with D J1 = −1.39 cm–1 for the type 1 hydrogen bonds and J2/k = −0.56 cm–1 for the type 2 hydrogen bonds.目标化合物结晶于单斜晶系P2₁/c空间群，晶胞参数为a=11.2470(3) Å，b=5.9034(2) Å，c=12.0886(3) Å，β=115.143(1)°，晶胞体积V=726.58(4) ų，其结构由离散的单核NiCl₂(邻苯二胺（o-phenylenediamine）)₂分子构成。每个o-phen配体以双齿配位模式配位，氯离子占据所得四方畸变八面体配位场的反式位置。两组独立的N–H···Cl氢键将该八面体分子组装为二维网络，其中1型相互作用沿c轴连接相邻的单核分子，2型相互作用沿bc平面内的对角线连接单核分子。对磁学数据的分析表明，除存在零场分裂现象外，层内还通过上述氢键存在弱反铁磁耦合；最优拟合结果来自一维反铁磁模型：对于D>0的模型，拟合参数为g=2.0917(7)，J/k=−2.11(4) K [J=−1.47(3) cm⁻¹]，D=1.05(3) cm⁻¹ [β=D/|J|=0.72(6)]；对于D<0的模型，拟合参数为g=2.0911(6)，J/k=−2.26(1) K [J=−1.57(1) cm⁻¹]，D=−0.86(1) cm⁻¹ [β=D/|J|=0.55(6)]，其中1型氢键对应J₁=−1.39 cm⁻¹，2型氢键对应J₂/k=−0.56 cm⁻¹。