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

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-O_perchlorate 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-O_water 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 Ag^I-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.