Synthesis, polymorphism, and shape complementarity-induced co-crystallization of hexanuclear Co() clusters capped by a flexible heteroligand shell

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 53; no. 16; pp. 712 - 722
• Main Authors: Terlecki, Micha, Kornowicz, Arkadiusz, Sacharczuk, Kornel, Justyniak, Iwona, Lewi ski, Janusz
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 23.04.2024
• Subjects: Cobalt acetates; Cobalt compounds; Cocrystallization; Crystal structure; Crystallization; Dehydration; Functional materials; Ligands; Metal clusters; Polymorphism; Reagents; Self-assembly; Structural analysis; Synthesis; Van der Waals forces
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d4dt00261j

Polymorphism and co-crystallization have gradually gained attention as new tools in the development of modern crystalline functional materials. However, the study on the selective self-assembly of metal clusters into multicomponent crystals is still in its infancy. Herein, we present the synthesis and characterization of two new heteroleptic hydroxido-acetato and acetato Co( ii ) clusters [Co 6 (OH) 2 (OAc) 4 ( pyret ) 6 ] ( 1 ) and [Co 6 (OAc) 6 ( pyret ) 6 ] ( 2 ) incorporating auxiliary 2-pyrrolidinoethoxylate ( pyret ) ligands. On this occasion, we revealed that the commonly used thermal procedure for dehydration of cobalt( ii ) acetate leads to a reagent comprising substantial contamination by cobalt hydroxido moieties. Comprehensive structural analysis of new compounds demonstrated intriguing crystal structure diversity of hydroxido-acetato cluster 1 , which represents a rare example of both conformational and packing polymorphism in one compound, originating from the flexibility of organic O , N -ligands in the secondary coordination sphere. Furthermore, both clusters exhibit an interesting propensity for the selective formation of co-crystals 1·2 driven mainly by van der Waals forces and specific shape complementarity between co-formers. We emphasize the pivotal role of proper purification of Co( ii ) acetate in the synthesis of two new heteroleptic acetato Co( ii ) 6 clusters and demonstrate their intriguing polymorphism and propensity for co-crystallization.