Supramolecular Structural Variations with Changes in Anion and Solvent in Silver(I) Complexes of a Semirigid, Bitopic Tris(pyrazolyl)methane Ligand

The bitopic ligand p-C6H4[CH2OCH2C(pz)3]2 (pz = pyrazolyl ring) that contains two tris(pyrazolyl)methane units
connected by a semirigid organic spacer reacts with silver(I) salts to yield {p-C6H4[CH2OCH2C(pz)3]2(AgX)2}∞,
where X = CF3SO3- (1), SbF6- (2), PF6- (3), BF4- (4), and NO3- (5). Crystallization of the first three compounds
from acetone yields {p-C6H4[CH2OCH2C(pz)3]2(AgCF3SO3)2}∞ (1a), {p-C6H4[CH2OCH2C(pz)3]2(AgSbF6)2[(CH3)2CO]2}∞ (2b), and {p-C6H4[CH2OCH2C(pz)3]2AgPF6}∞ (3a), where the stoichiometry for the latter compound has
changed from a metal:ligand ratio of 2:1 to 1:1. The structure of 1a is based on helical argentachains constructed
by a κ2−κ1 coordination to silver of the tris(pyrazolyl)methane units. These chains are organized into a tubular 3D
structure by cylindrical [(CF3SO3)6]6- clusters that form weak C−H···O hydrogen bonds with the bitopic ligand. The
same κ2−κ1 coordination is present in the structure of 2a, but the structure is organized by six different tris(pyrazolyl)methane units from six ligands bonding with six silvers to form a 36-member argentamacrocycle core.
The cores are organized in a tubular array by the organic spacers where each pair of macrocycles sandwich six
acetone molecules and one SbF6- counterion. The structure of 3a is based on a κ2−κ0 coordination mode of each
tris(pyrazolyl)methane unit forming a helical coordination polymer, with two strands organized in a double stranded
helical structure by a series of C−H···π interactions between the central arene rings. Crystallization of 2−4 from
acetonitrile yields complexes of the formula {p-C6H4[CH2OCH2C(pz)3]2[(AgX)2(CH3CN)n]}∞ where n = 2 for X =
SbF6- (2b), X = PF6- (3b) and n = 1 for X = BF4- (4b). All three structures contain argentachains formed by
a κ2−κ1 coordination mode of the tris(pyrazolyl)methane units linked by the organic spacer and arranged in a 2D
sheet structure with the anions sandwiched between the sheets. Crystallization of 5 from acetonitrile yields crystals
of the formula {p-C6H4[CH2OCH2C(pz)3]2(AgNO3)2(CH3CN)4}∞, where the nitrate is bonded to the silver. The
argentachains, again formed by κ2−κ1 coordination, are arranged in W-shaped sheets that have an overall
configuration very different from 2b−4b. Treating {p-C6H4[CH2OCH2C(pz)3]2(AgSbF6)2}∞ with a saturated aqueous
solution of KPF6 or KO3SCF3 slowly leads to complete exchange of the anion. Crystallization of a sample that
contains an approximately equal mixture of SbF6-/PF6- from acetonitrile yields {p-C6H4[CH2OCH2C(pz)3]2[Ag2(PF6)0.78(1)(SbF6)1.22(1)(CH3CN)2][(CH3CN)0.25 (C4H10O)0.25]}∞, a compound with a sheet structure analogous to 2b−4b. Crystallization of the same mixture from acetone yields {p-C6H4[CH2OCH2C(pz)3]2(AgSbF6)[(CH3)2CO]1.5}∞,
where the metal-to-ligand ratio is 1:1 and the [C(pz)3] units are κ2−κ0 bonded forming a coordination polymer. The
supramolecular structures of all species are organized by a combination of C−H···π, π−π, or weak C−H−F(O)
hydrogen bonding interactions.