Cyclic versus Polymeric Supramolecular Architectures in Metal Complexes of Dinucleating Ligands: Silver(I) Trifluoromethanesulfonate Complexes of the Isomers of Bis(di(1H-pyrazolyl)methyl)-1,1′-biphenyl.

In the search for new examples of
systems that self-assemble into
cyclic metal–organic architectures, the six isomers of X,Y′-bis­(di­(1H-pyrazolyl)­methane)-1,1′-biphenyl, LXY, and their silver­(I) trifluoromethanesulfonate
complexes were prepared. Five of the six silver complexes gave crystals
suitable for single crystal X-ray diffraction, with only the microcrystalline
derivative of 2,3′-bis­(di­(1H-pyrazolyl)­methane)-1,1′-biphenyl, L23, proving to be unsuitable for
this analysis. Of the structurally characterized silver­(I) complexes,
that with L22 showed an unusual
trans-spanning chelating coordination mode to silver. At the same
time the ligand was also bound to a second silver center giving rise
to a cyclic supramolecular isomer with a 22-membered metallacycle.
The complex of L34 also gave
a cyclic dication but with a remarkable 28-membered metallacycle ring.
The remaining three derivatives were polymeric. The results of this
study underscore that a 120° angle between dipyrazolylmethyl
moieties across aromatic spacers will give rise to a cyclic dication
but this is not an exclusive requirement for the formation of cyclic
architectures. Also, the supramolecular structures of complexes are
assembled via a variety of noncovalent interactions involving the
di­(pyrazolyl)­methyl cation most notably by weak hydrogen bonding interactions
involving the methine hydrogen and an oxygen atom of the triflate
anion.