International Tomography Center, Russian Academy of Sciences, 3A Institutskaya Street, 630090 Novosibirsk, Russian Federation.
Inorg Chem. 2011 May 16;50(10):4307-12. doi: 10.1021/ic1022483. Epub 2011 Apr 14.
The crystals of heterospin complexes [M(hfac)(2)L(2)] (where M = Cu, Ni, Co, or Mn; hfac = hexafluoroacetylacetonate; and L = nitronyl nitroxide, 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl) were found to make unusual jumping motions. Under ambient conditions, the jumping and various displacements of crystals lasted for several weeks. The mechanical motion was accompanied by the cracking and disintegration of crystals, and a solid [M(hfac)(2)(L(1))(2)] complex with the corresponding imino nitroxide 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihydro-1H-imidazole-1-oxyl (L(1)) was detected. The jumping was accompanied by the spontaneous elimination of oxygen, the source of which was the nitronyl nitroxyl fragment of coordinated L. An X-ray study of [M(hfac)(2)L(2)] (where M = Cu, Ni, Co, or Mn) showed that the molecular structure of all [M(hfac)(2)L(2)] and their packing in the solid state were identical. The packing of [M(hfac)(2)L(2)] was concluded to be critical to the mechanical effect. In complexes with different stoichiometries or different sets of diamagnetic ligands (Cu(hfac)(2)L, [Cu(hfac)(acac)L]·EtOH, [CuPiv(2)L(2)]·2CH(2)Cl(2), and [Cu(hfac)(2)L(2)Cu(2)Piv(4)]·3C(7)H(8) (where acac is acetylacetonate and Piv is trimethylacetate), or free L), the effect vanished when the packing changed.
异自旋配合物[M(hfac)(2)L(2)]（其中 M = Cu、Ni、Co 或 Mn；hfac = 六氟乙酰丙酮；L = 硝酰氮氧自由基，4,4,5,5-四甲基-2-(1-甲基-1H-咪唑-5-基)-4,5-二氢-1H-咪唑-1-氧自由基-1-氧）的晶体被发现会发生异常跳跃运动。在环境条件下，晶体的跳跃和各种位移持续了数周。机械运动伴随着晶体的破裂和崩解，并且检测到具有相应亚氨基硝氧自由基 4,4,5,5-四甲基-2-(1-甲基-1H-咪唑-5-基)-4,5-二氢-1H-咪唑-1-氧自由基-1-氧（L(1)）的固体[M(hfac)(2)(L(1))(2)]配合物。跳跃伴随着氧气的自发消除，其来源是配位 L 的硝酰氮氧自由基片段。对[M(hfac)(2)L(2)]（其中 M = Cu、Ni、Co 或 Mn）的 X 射线研究表明，所有[M(hfac)(2)L(2)]的分子结构及其在固态中的堆积方式完全相同。认为[M(hfac)(2)L(2)]的堆积方式对于机械效应至关重要。在具有不同化学计量比或不同的反磁性配体的配合物（Cu(hfac)(2)L、[Cu(hfac)(acac)L]·EtOH、[CuPiv(2)L(2)]·2CH(2)Cl(2)和[Cu(hfac)(2)L(2)Cu(2)Piv(4)]·3C(7)H(8)（其中 acac 是乙酰丙酮酸盐，Piv 是三甲基醋酸盐）或游离的 L）中，当堆积方式改变时，该效应消失。
