Silver(I) Complexes of Fixed, Polytopic Bis(pyrazolyl)methane Ligands: Influence of Ligand Geometry on the Formation of Discrete Metallacycles and Coordination Polymers

Reactions of the arene-linked bis(pyrazolyl)methane ligands m-bis[bis(1-pyrazolyl)methyl]benzene, (m-[CH(pz)2]2C6H4,
Lm), p-bis[bis(1-pyrazolyl)methyl]benzene, (p-[CH(pz)2]2C6H4, Lp), and 1,3,5-tris[bis(1-pyrazolyl)methyl]benzene (1,3,5-[CH(pz)2]3C6H3, L3) with AgX salts (pz = 1-pyrazolyl; X = BF4- or PF6-) yield two types of molecular motifs
depending on the arrangement of the ligating sites about the central arene ring. Reactions of the m-phenylene-linked Lm with AgBF4 and AgPF6 afford complexes consisting of discrete, metallacyclic dications:  [Ag2(μ-Lm)2](BF4)2 (1) and [Ag2(μ-Lm)2](PF6)2 (2). When the p-phenylene-linked Lp is treated with AgBF4 and AgPF6, acyclic,
cationic coordination polymers are obtained:  {[Ag(μ-Lp)]BF4}∞ (3) and {[Ag(μ-Lp)]PF6}∞ (4). Reaction of the ligand
L3, containing three bis(pyrazolyl)methane units in a meta arrangement, with an equimolar amount of AgBF4 again
yields discrete metallacyclic dications in which one bis(pyrazolyl)methane unit on each ligand remains unbound: 
[Ag2(μ-L3)2](BF4)2 (5). Treatment of L3 with an excess of AgBF4 affords a polymer of metallacycles, {[Ag3(μ-L3)2](BF4)3}∞ (6), with one of the bis(pyrazolyl)methane units on each ligand bound to a silver cation bridging two
metallacycles. The supramolecular structures of the silver(I) complexes 1−6 are organized by noncovalent interactions,
including weak hydrogen bonding, π−π, and anion−π interactions.