Smirnova Kristina A, Golomolzina Irina V, Romanenko Galina V, Fokin Sergey V, Tolstikov Svyatoslav E, Letyagin Gleb A, Chernavin Platon A, Bogomyakov Artem S
International Tomography Center, Siberian Branch, Russian Academy of Sciences, 630090, Institutskaya str., 3a, Novosibirsk, Russia.
Dalton Trans. 2024 Aug 6;53(31):13119-13128. doi: 10.1039/d4dt01861c.
Spontaneous solvent-controlled solid-state transformations were observed for a series of polymeric chain solvates [Cu(hfac)L]·0.5Solv (Solv = (CH)CO, THF, CHCl, CHBr, CHCl) with 2-(1-propyl-1-imidazol-5-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1-imidazole-3-oxide-1-oxyl (L) under ambient conditions. The conversion of powdered polymeric chain [Cu(hfac)L]·0.5THF and [Cu(hfac)L]·0.5(CH)CO complexes, accompanied by the loss of solvent molecules, occurs completely to binuclear [Cu(hfac)L] within a day. On the other hand, in the case of [Cu(hfac)L]·0.5Solv (Solv = CHCl, CHBr, CHCl), the partial transformation into a desolvated 1D polymer [Cu(hfac)L] or its mixture with [Cu(hfac)L] takes much longer time. The magnetic behavior of the isostructural solvates is highly sensitive to the included solvent molecules. The complexes with THF, CHCl, CHBr, and CHCl undergo a transition to a magnetically ordered state below 4 K, a phenomenon reported for the first time for the polymeric chain Cu(II) complexes with a "head-to-tail" motif. [Cu(hfac)L]·0.5THF and [Cu(hfac)L]·0.5(CH)CO undergo a spin transition at 190 K, which is induced by the transformation of the Cu atom environment. In the case of the THF solvate, the increase in the distances between the Cu and oxygen atoms leads to enhanced ferromagnetic exchange interactions, while in the acetone solvate, the nitroxide coordination type changes from axial to equatorial at certain coordination sites, resulting in the emergence of strong antiferromagnetic exchange.
在环境条件下，观察到一系列含聚合物链溶剂合物[Cu(hfac)L]·0.5Solv（Solv = (CH)CO、THF、CHCl、CHBr、CHCl）与2-(1-丙基-1-咪唑-5-基)-4,4,5,5-四甲基-4,5-二氢-1-咪唑-3-氧化物-1-氧基（L）发生自发的溶剂控制固态转变。粉末状聚合物链[Cu(hfac)L]·0.5THF和[Cu(hfac)L]·0.5(CH)CO配合物在一天内完全转化为双核[Cu(hfac)L]，同时伴随着溶剂分子的损失。另一方面，对于[Cu(hfac)L]·0.5Solv（Solv = CHCl、CHBr、CHCl），部分转化为去溶剂化的一维聚合物[Cu(hfac)L]或其与[Cu(hfac)L]的混合物则需要更长时间。同构溶剂合物的磁行为对所含溶剂分子高度敏感。含有THF、CHCl、CHBr和CHCl的配合物在4 K以下转变为磁有序状态，这是首次报道具有“头对尾” motif的聚合物链Cu(II)配合物出现这种现象。[Cu(hfac)L]·0.5THF和[Cu(hfac)L]·0.5(CH)CO在190 K发生自旋转变，这是由Cu原子环境的转变引起的。在THF溶剂合物的情况下，Cu与氧原子之间距离的增加导致铁磁交换相互作用增强，而在丙酮溶剂合物中，某些配位位点的氮氧化物配位类型从轴向变为赤道向，导致出现强反铁磁交换。
