The reaction of the flexible ligand 2,5-bis((pyridin-2-ylmethyl)thio)-1,3,4-thiadiazole (bptz) with cobalt(II) chloride afforded a mononuclear cyclic compound [CoCl₂(bptz)]·1/2MeCN (1), which in the solid state quickly transformed through an irreversible ring-opening polymeric process to a one-dimensional compound [CoCl₂(bptz)] (2), triggered by the loss of lattice solvent molecules at room temperature. The transformation involved the reconstruction of coordination bonds and drastic changes in the ligand conformation, which thus resulted in vigorous lattice variations. Self-consistent-charge density-functional tight-binding (SCC-DFTB) calculations confirmed that this transformation was spontaneous. This result not only means the realization of solid-state single-crystal-to-single-crystal transformation, but also gives a deep insight into the mechanism of bond reconstruction.

中文翻译：

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Co（II）化合物中的开环聚合单晶到单晶转变

柔性配体2,5-双（（吡啶-2-基甲基）硫基）-1,3,4-噻二唑（bptz）与氯化钴（II）的反应提供了单核环状化合物[CoCl ₂（bptz）] ·1 / 2MeCN（1），固态时会通过不可逆的开环聚合过程迅速转变为一维化合物[CoCl ₂（bptz）]（2），这是由于室温下晶格溶剂分子的损失所致。该转变涉及配位键的重建和配体构象的急剧变化，从而导致剧烈的晶格变化。自洽电荷密度功能紧密结合（SCC-DFTB）计算证实了这种转变是自发的。该结果不仅意味着实现固态单晶至单晶的转变，而且还对键重建的机理提供了深刻的认识。