Silver Coordination Polymers Based on Neutral Trinitrile Ligand: Topology and the Role of Anion

Abstract

One flexible star-shaped bridging molecule tris-(4-cyanophenyl)amine (TCPA) is synthesized from tris-(4-iodophenyl)amine by treatment with CuCN in hexamethylphosphorotriamide (HMPA) as a catalyst in high yield. Anion-template-controlled reactions of TCPA and silver salts give a series of coordination polymers (CPs) with various topological patterns. The complex [Ag(TCPA)(ClO4)]n·nC6H6 (1) forms an undulating 4.82 network, which displays unusual net entanglement. Two 4.82 nets interweave each other to give rise to 2-fold interpenetrating basic layers, which link together via double μ-Operchlorate bridging interactions. The complex [Ag(TCPA)(CF3SO3)]n·2nC6H6 (2) forms noninterpenetrating (6,3) nets. The solid state structure of [Ag3(TCPA)(CF3CO2)3]n·nCH2Cl2 (3) also is a (6,3) honeycomb network, differently, including a sphere-type Ag4(CF3CO2)62− cluster-anion in the host frameworks, which is a rare example of the host cationic network containing a guest cluster-anion. The complexes [Ag(TCPA)(BF4)·0.5H2O]n·1.5nC6H6 (4), [Ag(TCPA)(ClO4)·0.5H2O]n·nC7H8·nH2O (5), and [Ag(TCPA)(CF3SO3)·0.5H2O]n·1.5nC6H6 (6) exhibit three similar (10,3) networks which form rare net entanglements. Four (10,3) nets interweave to generate a 4-fold interpenetrating assemble, which are closely united together via specific μ2-Owater bridging interactions. The complex [Ag4(TCPA)2(CF3CO2)3(CF3SO3)]n·nC6H6·nCH2Cl2 (7) is a three-dimensional (3D) structure formed via multiple “zigzag” Ag4 chains. In this AgI-TCPA system, the structural diversities and topological differences of these networks result from the flexibilities of the bridging ligand TCPA and the template-effect of anions. The free rotation of three Ph−CN “arms” around the central N moiety results in TCPA adopting different conformation in the self-assembly process by using variational solvent system and/or counterions.