Crystal Engineering of Cyanoborate‐Bridged Cubane‐Type Tetranuclear Ru Complex: Synthesis, Pseudopolymorphism, and Coordination Polymer Formation

Abstract Cyanoborate anions are versatile bridging ligands that lead to structurally diverse compounds from a crystal engineering perspective. Herein, we report the synthesis of a cubane‐type tetranuclear Ru complex, [Ru 4 (Cp) 4 {B(CN) 4 } 4 ] ( 1 , Cp = C 5 H 5 ), obtained by photoirradiation of [Ru(Cp)(C 6 H 6 )]B(CN) 4 in solution or by the reaction of [CpRu(MeCN) 3 ] + with KB(CN) 4 . This complex served as a host for various solvents, generating different pseudopolymorphs, including 1· n CH 2 Cl 2 ( n = 1, 2, 3), 1·0.5C 6 H 6 , 1·C 6 H 5 Me , and 1·3THF upon recrystallization. Moreover, the four free cyano groups in 1 allow it to act as a bridging ligand, facilitating the formation of 1D and 2D coordination polymers through reactions with transition metal complexes.