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

• Published in: Chemistry : a European journal 2016-12, Vol.22 (49), p.17576-17580
• Main Authors: Zhang, Zongyao, Zheng, Kunyi, Xia, Tianlong, Xu, Lijin, Cao, Rui
• Format: Article
• Language: English
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201604598

Reactions of trinickel complex of tripodal tris-tacn ligand N(CH -m-C H -CH tacn) (L, tacn=1,4,7-triazacyclononane) in acetonitrile-methanol solution with and without phosphate led to two complexes of distinct nuclearities, [(Ni Cl) (CH OH) (HPO )L](PF ) (Ni , 1) and [(Ni (CN) (H O) Cl) L ]Cl (Ni , 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 L to form 1. In the absence of phosphate, Ni L assembles with cyanide ions, which are formed by Ni-catalyzed C-CN bond cleavage of acetonitrile, to give a nano-sized Ni cage. Complex 2 represents a discrete truncated octahedron cage assembled with [Ni (CN) ] 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.