656231-46-8

Relevant academic research and scientific papers

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[CH2OCH 2C(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[CH 2OCH2C(pz)3]2(AgX) 2}∞, where X = CF3SO3- (1), SbF6- (2), PF6- (3), BF 4- (4), and NO3- (5). Crystallization of the first three compounds from acetone yields {p-C 6H4[CH2OCH2C(pz)3] 2(AgCF3SO3)2}∞ (1a), {p-C 6H4[CH2OCH2C(pz)3] 2(AgSbF6)2[(CH3)2CO] 2}∞ (2b), and {p-C6H4[CH 2OCH2C(pz)3]2AgPF 6}∞ (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-κ 1 coordination to silver of the tris(pyrazolyl)methane units. These chains are organized into a tubular 3D structure by cylindrical [(CF 3SO3)6- clusters that form weak C-H...O hydrogen bonds with the bitopic ligand. The same κ2-κ 1 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-κ 0 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[CH2OCH 2C(pz)3]2[(AgX)2(CH 3CN)n]∞ where n = 2 for X = SbF6 - (2b), X = PF6- (3b) and n = 1 for X = BF 4- (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-C6H 4[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-C 6H4[CH2OCH2C(pz)3] 2[Ag2(PF6)0.78(1)(SbF 6)1.22(1)(CH3CN)2][(CH 3CN)0.25 (C4H10O) 0.25]}∞, a compound with a sheet structure analogous to 2b-4b. Crystallization of the same mixture from acetone yields {p-C6H 4[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.