Solid-State Spin Crossover of Ni(II) in a Bioinspired N3S2 Ligand Field

详细信息    查看全文

• 作者：Huaibo Ma ; Jeffrey L. Petersen ; Victor G. Young ; Jr. ; Gordon T. Yee ; Michael P. Jensen
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：April 20, 2011
• 年：2011
• 卷：133
• 期：15
• 页码：5644-5647
• 全文大小：746K
• 年卷期：v.133,no.15(April 20, 2011)
• ISSN：1520-5126

文摘

The complex Tp^Ph,MeNiS₂CNMe₂ [Tp^Ph,Me = hydrotris(3-phenyl-5-methyl-1-pyrazolyl)borate] features a bioinspired N₃S₂ ligand set supporting a five-coordinate, trigonally distorted square-pyramidal geometry in the solid state. Spin crossover of Ni(II) was demonstrated by temperature-dependent X-ray crystallography and magnetic susceptibility measurements. The crystal lattice contains two independent molecules (i.e., Ni1 and Ni2). At 293 K, the observed bond lengths and susceptibility are consistent with high-spin (S = 1) Ni(II), and both molecules exhibit relatively short axial Ni鈭扤 bonds and long Ni鈭扤 and Ni鈭扴 equatorial bonds. At 123 K, the Ni1 complex remains high-spin, but the Ni2 molecule substantially crosses to a structurally distinct diamagnetic (S = 0) state with significant elongation of the axial Ni鈭扤 bond and offsetting contraction of the equatorial bonds. The temperature-dependent susceptibility data were fit to a spin equilibrium at Ni2 [螖H掳 = 1.13(2) kcal/mol and 螖S掳 = +7.3(1) cal mol^鈭? K^鈭?] consistent with weak coupling to lattice effects. Cooling below 100 K results in crossover of the Ni1 complex.