Crystal structures and magnetic properties of two molecular solids based on bis(maleonitriledithiolate)nickelate monoanion with substituted piperidinium cations

作者：Zhou Jia rong; Chen Xing; Hou Yong; Zheng Ying ying; Huang Qian; Zuo Hong rong; Yang Le min; Ni Chun lin^*; Meng Qing jin

来源：Synthetic Metals, 2010, 160(7-8): 797-802.

DOI：10.1016/j.synthmet.2010.01.025

• Bis(maleonitriledithiolate)nickelate(III) anion
• Substituted piperidinium
• Crystal structure
• Overlapping mode
• Magnetic properties
• Spin-gap transition

Two new molecular solids, [1-NaMePid][Ni(mnt)(2)] (1) and [2-NaMePid][Ni(mnt)(2)] (2) (mnt(2-) = maleonitriledithiolate, [1-NaMePid](+) = 1-(1'-naphthylmethyl)piperidinium and [2-NaMePid](+) = 1-(2'-naphthylmethyl)piperidinium) have been characterized structurally and magnetically. Both [Ni(mnt)(2)](-) anions and the cations of 1 and 2 form segregated column stacks, and the Ni(III) ions form a 1D zigzig alternating magnetic chain within a [Ni(mnt)(2)](-) column through Ni center dot center dot center dot S, S center dot center dot center dot S, Ni center dot center dot center dot Ni, or pi-pi interactions. Some conformational features in two isomeric cations and the geometry of the individual [Ni(mnt)(2)](-) anion for 1 and 2 remain similar, while the changes of the space filling properties, the packing requirements and the existence of the water molecule in 2 result in the difference of the stacking mode of the [Ni(mnt)(2)](-) anions. Magnetic susceptibility measurements in the temperature range 2-300 K show that 1 is diamagnetism, while 2 exhibits a novel and interesting spin-gap transition around 16.8K with antiferromagnetic interaction (J = -4.6cm(-1)) in the high-temperature phase (HT) and the spin-gap (Delta/k(b) = 68.5K) in the low-temperature phase (LT).

• 单位
  南京大学; 中国农业大学; 华南农业大学