Ni 3 versus Ni 30 : A Truncated Octahedron Metal–Organic Cage Constructed with [Ni 5 (CN) 4 ] 6+ Squares and Tripodal Tris‐tacn Ligands That are Large and Flexible

Reactions of trinickel complex of tripodal tris‐tacn ligand N(CH 2 ‐ m ‐C 6 H 4 ‐CH 2 tacn) 3 ( L , tacn=1,4,7‐triazacyclononane) in acetonitrile–methanol solution with and without phosphate led to two complexes of distinct nuclearities, [(Ni II Cl) 3 (CH 3 OH) 3 (HPO 4 ) L ](PF 6 ) (Ni 3 , 1 ) and [(Ni II 5 (CN) 4 (H 2 O) 8 Cl) 6 L 8 ]Cl 30 (Ni 30 , 2 ). Ligand L takes upward and downward conformation in the structure of 1 and 2 , respectively. It is proposed that phosphate directs the upward conformation of Ni 3 L to form 1 . In the absence of phosphate, Ni 3 L assembles with cyanide ions, which are formed by Ni‐catalyzed C−CN bond cleavage of acetonitrile, to give a nano‐sized Ni 30 cage. Complex 2 represents a discrete truncated octahedron cage assembled with [Ni 5 (CN) 4 ] 6+ squares and large and flexible triangular ligands, which is scarcely observed for self‐assembled metal‐organic cages. The magnetic properties of 1 and 2 were examined, showing intriguing magnetic properties.