Synthesis and Structural Characterization of a Silver(I) Pyrazolato Coordination Polymer

Coinage metal(I)center dot center dot center dot metal(I) interactions are widely of interest in fields such as supramolecular assembly and unique luminescent properties, etc. Only two types of polynuclear silver(I) pyrazolato complexes have been reported, however, and no detailed spectroscopic characterizations have been reported. An unexpected synthetic method yielded a polynuclear silver(I) complex [Ag(mu-L1Clpz)](n) (L1Clpz(-) = 4-chloride-3,5-diisopropyl-1-pyrazolate anion) by the reaction of {[Ag(mu-L1Clpz)](3)}(2) with ((Bu4N)-Bu-n)[Ag(CN)(2)]. The obtained structure was compared with the known hexanuclear silver(I) complex {[Ag(mu-L1Clpz)](3)}(2). The Ag center dot center dot center dot Ag distances in [Ag(mu-L1Clpz)](n) are slightly shorter than twice Bondi's van der Waals radius, indicating some Ag center dot center dot center dot Ag argentophilic interactions. Two Ag-N distances in [Ag(mu-L1Clpz)](n) were found: 2.0760(13) and 2.0716(13) angstrom, and their N-Ag-N bond angles of 180.00(7)degrees and 179.83(5)degrees indicate that each silver(I) ion is coordinated by two pyrazolyl nitrogen atoms with an almost linear coordination. Every five pyrazoles point in the same direction to form a 1-D zig-zag structure. Some spectroscopic properties of [Ag(mu-L1Clpz)](n) in the solid-state are different from those of {[Ag(mu-L1Clpz)](3)}(2) (especially in the absorption and emission spectra), presumably attributable to this zig-zag structure having longer but differently arranged intramolecular Ag center dot center dot center dot Ag interactions of 3.39171(17) angstrom. This result clearly demonstrates the different physicochemical properties in the solid-state between 1-D coordination polymer and metalacyclic trinuclear (hexanuclear) or tetranuclear silver(I) pyrazolate complexes.

Automated summary

The study obtained a polynuclear silver(I) complex through an unexpected synthetic method, revealing the presence of argentophilic interactions. The complex forms a 1-D zig-zag structure with distinct spectroscopic properties in the solid-state compared to other silver(I) complexes.