Naumov Pance, Sakurai Kenji, Asaka Toru, Belik Alexei A, Adachi Shin-ichi, Takahashi Junichi, Koshihara Shin-ya
International Center for Young Scientists, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
Inorg Chem. 2006 Jun 26;45(13):5027-33. doi: 10.1021/ic060110s.
The structural grounds of the decrease of point and lattice symmetries coupled with switching of the exchange interaction in single crystals of a highly strained, coordinationally unsaturated bisdiaminecopper(II) cation are described. The combined magnetic susceptibility and X-ray diffraction results indicate that the interplay between the inherent vibronic instability and ligand-field strain imposed by moderately flexible, coordinationally shielding ligands enables effective switching of the pseudo-Jahn-Teller d9 centers between states with different exchange interaction in the low-temperature regime and valence orbital orientation and coordination geometry in the high-temperature regime. Within the low-temperature hysteresis region, the phase transition can also be induced by excitation of the ligand-to-metal charge-transfer bands, resulting in overall shrinkage of the lattice. The compound is a prototype of weakly electronically coupled one-dimensional Jahn-Teller systems, which can undergo phase transitions induced by light, in addition to heating, cooling, and change of pressure, and it represents a prospective basis for the design of switching materials capable of multimode external control.
描述了在高度应变、配位不饱和的双二胺铜（II）阳离子单晶中，点对称性和晶格对称性降低以及交换相互作用切换的结构基础。结合的磁化率和X射线衍射结果表明，由适度柔性的配位屏蔽配体施加的固有振动电子不稳定性与配体场应变之间的相互作用，使得伪 Jahn-Teller d9 中心在低温下能够在具有不同交换相互作用的状态之间有效切换，在高温下能够实现价轨道取向和配位几何结构的切换。在低温滞后区域内，配体到金属电荷转移带的激发也可诱导相变，导致晶格整体收缩。该化合物是弱电子耦合一维 Jahn-Teller 系统的原型，除了加热、冷却和压力变化外，还可通过光诱导相变，它为设计能够进行多模外部控制的开关材料提供了一个有前景的基础。
